Search This Blog
Showing posts with label Electricity/Electronics. Show all posts
Showing posts with label Electricity/Electronics. Show all posts

Thursday, October 16, 2025

Gun & Prepping News #51

Just some gun and prepping related links that I thought interesting or useful:   

     And after three decades of studying how violence really works . . .  After training both the heroes and witnessing the methods of monsters . . .  I've learned something that will disturb you.  The "bad guys" are better at violence than the "good guys."  Not because they're stronger.  Not because they're smarter.  But because they understand something our heroes have forgotten.  Violence isn't about technique.  It's not about style.  It's not about fighting "fair".  Violence is a tool.  And like any tool, it works best when you understand its true purpose.  A hammer isn't designed to be pretty.  It's designed to drive nails.  Violence isn't designed to be civilized.  It's designed to end threats.   

Old cops give young cops a warning: “Every time you’re in a fight, there’s a loaded gun present. Yours.”

He then goes on to describe some items that can help in a fight over the gun: a manual safety (the person grabbing your weapon may not know its there or how to disengage it), using a retention holster, and learning retention skills. As for retention holsters, Ayoob recommends the Rogers/Safariland SS-III/070 holster.

  • "SPAS-12 History Value: Legacy and Rising Price"--The Truth About Guns.  This was an Italian shotgun developed for military or police which claim to fame was that it was a semi-auto that could also be operated like a pump-action. Cool idea, but it made it complicated and heavy. And it probably would have faded into obscurity except that it had a certain chic aura about it, reinforced by its popularity in movies, video games and with military contractors. The article delves into the weapon and it being banned from import after the Assault Weapon Ban went into effect, its impact on popular culture, and current values with the author noting that "[a]s of 2025, the SPAS-12 remains one of the hottest collectibles in the firearms market, with some pristine examples exceeding $10,000 at auction."
  • "Which Doesn’t Belong and Why"--Tactical Wire. One of the main reasons cited for using factory ammunition over handloads is reliability, which itself is a product of the quality control undertaken by the manufacturer. But that doesn't guarantee that bad rounds (or even whole batches) don't get through. The author goes through some of the things he has seen with factory ammo including bullets seated too deeply or even backwards, cases that had no flash hole, bullets seated out of alignment mangling both the bullet and the case, and more. The author suggests:

    The point is, before you load up – particularly if it’s duty/carry ammo – visually inspect each round. A smart move is to remove the barrel from the pistol the ammo’s meant for (or the revolver’s cylinder) and drop each round into the chamber.  

    This checks easy fit. Upend the barrel/cylinder; does the round fall out? That’s also a good sign.

    If the rounds are loaded in those factory boxes with individual round trays, take that opportunity to check the case heads for dings, deformation – and check the primers to ensure they’re seated in the proper orientation and seated just below flush. 

I wanted to take the class because I am a firm believer in carrying what I call ‘Intermediate Force Options.’ Pepper spray is one of those weapons that give us a response to predatory behavior not requiring deadly force. As I state in all my classes “Lacking an intermediate force option while you are armed with a firearm implies that all you are willing to do to protect yourself is kill someone.” That’s not a position most reasonable people would be comfortable in taking, given a little bit of thought. 

  • Another article for the hunters: "The Gutless vs. Gutting Method for Field Dressing a Deer"--Montana Knife Company. This is not so much a "how-to" article as a "pros versus cons". I hadn't heard of the gutless method, but the author briefly explains: "The gutless method is a way of breaking down an animal without removing the guts from the body cavity." The author isn't favorably disposed toward the gutless method, but admits it has its uses with large animals, giving an example of a moose that was so large he and his hunting buddy were not initially able to flip the animal over and so had to resort to the gutless method. 
  • "Your smartphone apps are tracking you"--Behind the Black. We've probably all had the experience of talking about some product or issue with someone, only to suddenly have advertisements start popping up about that very thing. But this goes a bit beyond that. From the article:
Researchers have now found that though there is no evidence that big software companies like Facebook and Google are tracking your smartphone conversations, the data instead shows that the many apps you routinely install on your phone are spying on you quite extensively by periodically taking screenshots of things you look at and sending those images to third parties. 

The article the author cites notes: "Out of over 17,000 Android apps examined, more than 9,000 had potential permissions to take screenshots," and a number of those were caught doing exactly that.

A rarely observed solar pattern—known as the Centennial Gleissberg Cycle (CGC)—may have just “restarted,” according to scientists monitoring long-term solar trends. If confirmed, this transition could mark the beginning of decades of intensified solar activity, with potentially serious implications for satellites, astronauts, and space-based infrastructure on Earth.

    Fire plays a crucial role in meeting survival needs. Without it, nights turn freezing, food stays raw, and drinking water remains unsafe. However, a fire kit isn’t always as simple as striking a match to make a crackling flame appear. To make sure you’re ready to build a fire whenever it’s needed, having a fire-starting kit is a smart move.

    But what’s a fire-starting kit? It’s a compact, waterproof set of essentials designed to work in any weather. It should include at least three ignition tools, weatherproof tinder, and extra survival tools. This guide shows you how to build a fire-starting kit that won’t likely fail when you need it most.
 
The rest of the article goes into detail on assembling a kit, other tools that will be useful, and building a fire.
  • "A Simplified Disaster Network" (Part 1) (Part 2)--Survival Blog. The author explains:

Having an operational computer network running in a post-SHTF world may seem frivolous to some people. But if you have any plans to use computers, tablets, or cell phones as part of your post-disaster operations, it can provide the capability for those devices to communicate, share data and synchronize their activities. It can also provide some support for important things like WiFi security cameras and WiFi sensor monitoring.

The author had previously authored a series of articles on how to set up a mobile WiFi/Ethernet network. But he had some people complain it was too complicated and whether there was a simpler alternative. These two articles offer that simpler alternative. The first article goes over hardware and configuration. The second article goes over synchronizing files and "packaging" of all of the equipment to make it portable, along with some odds and ends.

  • "Getting Home by Rail"--Blue Collar Prepping. An article about using rail lines (both active and abandoned) to either bug out or to get home in the midst of a disaster, including links to maps showing them. He also goes over the pros and cons of walking the rails. 
  • "Working My Way Up — Part 1: Living In A Storage Shed"--Self-Reliance. The author found herself in dire financial straits with nothing to her name but a small rural plot, a camper in which to live, and a small storage shed. With winter coming on and the camper being inadequate for the winter, she made the storage shed her living space. She describes what she did to make the shed more livable. 
By at 2 comments:
Labels: , , , , , , , ,

Tuesday, September 30, 2025

Review of a Couple of Small Radios For Preppers

 The first video reviews a sub-$100 radio that might be useful for a prepper: the Radtel RT-950. One of the more interesting features is that the radio can as act a cross-band repeater. The second video discusses the difference between the basic RT-950 reviewed in the first video against a slightly more expense "Pro" model. The only real differences between the two is that the "Pro" version can transmit on the CB bands while the basic version can only receive CB frequencies; and the "Pro" can also receive upper and lower side bands. But for a $12 difference, it is probably worth getting the "Pro" version. 

 VIDEO: "I Review The Radtel RT-950 Ham Radio for SHTF & Emergency Comms"
NotaRubicon Productions (16 min.)

 

 VIDEO: "Radtel RT-950 PRO vs RT-950 Unlocked Ham Radios For SHTF"
NotaRubicon Productions (8 min.)

By at No comments:
Labels: , , ,

Monday, July 28, 2025

Science #6

 

Source

Some more "sciency" articles that have caught my attention:

    A recent article from Watts Up With That highlights recent climate developments in Antarctica, emphasizing that the continent has seen more snowfall and experienced record low temperatures in late winter 2023, particularly in July and August. These extreme cold events were widespread, affecting both East and West Antarctica, including the Ross Ice Shelf and the Antarctic Peninsula.

* * *

[Update: the black sarcophagi portion, below, appears to be fake news from a site in Azerbaijan]  

    Meanwhile, recent reports describe the discovery of four mysterious black sarcophagi beneath Antarctica’s. These artifacts, unearthed by an international team of scientists from the United States, Russia, China, and India, have sparked widespread intrigue and speculation due to their unknown origins and design.

    According to Baku.ws, the discovery of the black sarcophagi is unlike any other found in Antarctica. These objects were not just typical archaeological artifacts; they appeared to have an advanced design, one that did not fit with any known human history. Upon opening one of the sarcophagi, the scientists encountered an even more puzzling find. Inside was a hot metallic cylinder, etched with thin, mysterious lines. The object’s temperature and peculiar markings only added to the air of mystery surrounding the sarcophagi.

    With the cylinder inside the sarcophagus seemingly capable of holding immense energy or power, the team of researchers made the decision to leave the sarcophagi undisturbed. They carefully returned the objects to their original location, citing safety concerns and an inability to fully comprehend the nature of the find. Yet, the unanswered questions surrounding the discovery continue to puzzle scientists worldwide. 

* * *

    Meanwhile, scientists have recently detected unusual radio signals originating from beneath the Antarctic ice. These signals were picked up by the Antarctic Impulsive Transient Antenna (ANITA) experiment, a NASA-funded project that uses balloon-borne instruments to detect radio waves from cosmic rays interacting with the Earth’s atmosphere. 

    Further analysis indicates the second star is six magnitudes fainter than Betelgeuse with a mass about 1.5 times that of the sun. It also is likely an A- or B-type pre-main-sequence star, meaning it is a young, hot blue-white star that isn’t yet burning hydrogen in its core.

    Betelgeuse and its companion star were likely born at the same time, but their relationship won’t end well. According to the study’s authors, tidal forces will eventually cause the latter object to spiral into its partner, initiating an end to both of them. That said, astronomers estimate the pair’s finale will take place sometime within the next 10,000 years.

    But before that, researchers hope to study the two stars even more. Their next chance will begin in November 2027, when the stellar companion’s orbit places it at its furthest distance from Betelgeuse. 

    Lindzen and Happer use physics to demonstrate that CO2’s warming effect is limited by its logarithmic absorption of infrared radiation. The warming effect of each molecule of CO2 decreases as its concentration increases. They estimate low climate sensitivity (~0.5–1.5°C per CO2 doubling), which is far below the IPCC’s range of 2.5–4°C.

    They contend that Hurricanes, droughts, and floods exhibit no apparent increase in frequency driven by CO2, with natural variability dominating (e.g., NOAA’s stable hurricane frequency since 1980). They demonstrate that higher CO2 levels enhance photosynthesis, resulting in a 14% global greening trend (NASA, 1982–2015) and a 20% increase in crop yields (FAO, 2000–2020).

    They then emphasize that phasing out fossil fuels, which supply 80% of global energy (IEA, 2023), will raise costs and harm developing nations, with minimal climate benefit. Their physics-based approach challenges high-sensitivity climate models, which have overestimated warming in periods such as 1998–2014. They also align with skepticism of alarmist policies, like EPA regulations, which they’ve called a “hoax” in prior work.

Draw a circle with a 2,485-mile radius around the southern Chinese city of Yuxi. British geographer Alasdair Rae did just that — and inside it resides 55% of the world’s population: some 4.3 billion people crammed into just 7% of Earth’s surface. The region includes China, India, much of Southeast Asia, and parts of Pakistan. Some of it — like the Tibetan Plateau and the Taklamakan Desert — is barren. But the rest is packed with cities, factories, and the aspirations of hundreds of millions clawing their way toward modern life. 

    Imagine if nearly a third of your DNA was composed of ancient viral remnants—genetic hitchhikers from infections that occurred millions of years ago. 

    Now imagine that these viral fragments aren’t just dead weight, but have quietly evolved to help control the way your genes work, potentially shaping what it means to be human.

    That’s the startling insight behind a new study led by researchers at Kyoto University’s Institute for the Advanced Study of Human Biology (ASHBi) and McGill University. 

    Studies indicate that children with autism spectrum disorder (ASD) tend to have lower levels of vitamin D compared to their peers — the so-called “sunshine vitamin” is crucial for fetal brain development.

    Unfortunately, research exploring the effects of traditional vitamin D supplementation on autism symptoms has produced mixed results.

    Now, a new study out of Egypt suggests that a form of vitamin D3 known as nanoemulsion shows promise in improving symptoms. 

In a deeply troubling development, Israeli military scientists have genetically modified one of the deadliest bioweapons known to man—Yersinia pestis, the bacterium that causes pneumonic plague—and then used its altered genetic material to engineer a new mRNA vaccine that programs human cells to manufacture plague proteins tied to virulence and immune system evasion. 

I wonder if this was at the bioweapon facility targeted by Iran. 

    In the 30 years that biomedical researchers have worked determinedly to find a cure for Alzheimer’s disease, their counterparts have developed drugs that helped cut deaths from cardiovascular disease by more than half, and cancer drugs able to eliminate tumors that had been incurable. But for Alzheimer’s, not only is there no cure, there is not even a disease-slowing treatment.

    The brain, Alzheimer’s researchers patiently explain, is hard — harder than the heart, harder even than cancer. While that may be true, it is increasingly apparent that there is another, more disturbing reason for the tragic lack of progress: The most influential researchers have long believed so dogmatically in one theory of Alzheimer’s that they systematically thwarted alternative approaches. Several scientists described those who controlled the Alzheimer’s agenda as “a cabal.”  

A small group of researchers controlling what is published--and, hence, what is funded--is probably a problem in many other fields. String theory, anyone? But there is hope: "Breakthrough as two FDA-approved drugs are found to reverse Alzheimer’s — including restoring memory"--New York Post. Using a theory that Alzheimer's interferes with gene expression, the researchers first looked for drugs that would reverse that gene expression and focused on two candidates: letrozole and irinotecan, both currently used as cancer treatments. Initial tests on mice showed the drugs could restore memory and learning in mice showing severe symptoms. The article also mentions a few other drugs that have shown promise in treating Alzheimer's.

    For years, researchers at Oak Ridge National Laboratory (ORNL) in Tennessee have carefully managed leftover materials like Uranium-233. 

    This highly radioactive isotope has been stockpiled since the 1940s, when it was used in the Manhattan Project to build the first atomic bombs. 

     During the disposal process, scientists discovered they could extract an extremely rare byproduct of aging uranium, called Thorium-229.

* * *

    As Thorium-229 breaks down, it produces Actinium-225 (Ac-225), an isotope that can destroy tumors without harming surrounding healthy tissue. 

    In April, researchers in China created a controlled field to detonate a hydrogen explosive bomb that produced devastating results but without nuclear materials. Created by the China State Shipbuilding Corporation’s (CSSC) 705 Research Institute, the device is 2kg (4.4 lbs) and has a firing temperature of 1,000 degrees Celsius (1,832 degrees Fahrenheit) for a total of two seconds. By comparison, this bomb’s short duration is 15 times longer than any TNT blast, while including no atomic components. 

    Instead, the new device uses a magnesium hydride compound. Magnesium hydride can uniquely store hydrogen in amounts exceeding a pressurized tank’s. This silvery powder was initially designed to deliver hydrogen to off-grid locations, where it could be used to power fuel cells for clean energy and heating.

    CSSC research scientist Wang Xuefeng, the study lead, says, “Hydrogen gas explosions ignite with minimal ignition energy, have a broad explosion range, and unleash flames that race outward rapidly while spreading widely.”  

    Now, though, a couple of developments could finally push high-temperature superconductors into commercial use. One is the availability, at relatively moderate cost, of copper-oxide-based superconducting tape, which is being produced by a few companies for startups working on tokamak fusion reactors. The reactors use the superconducting tape, which is typically made of yttrium barium copper oxide, in powerful electromagnets. The other development involves a different group of startups that are using the tape to build electric motors with very high power-to-weight ratios, mainly for use in electric aircraft.

    Among that latter group of startups is Hinetics, formed in 2017 to commercialize research led by Kiruba Haran at the University of Illinois Urbana-Champaign. This past April, the company tested a prototype motor outfitted with superconducting rotor magnets. According to Haran, the tests, which included spinning a propeller in a laboratory setup, validated key components of the company’s designs for superconducting motors that will operate at power levels of 5 and 10 megawatts. Such levels would be high enough to power a regional passenger airliner with multiple motors. The work was funded in part by a grant from the Advanced Research Projects Agency–Energy (ARPA-E). 

    Gone are the days when drone warfare meant operations conducted from sprawling airfields in friendly territory or military bases thousands of miles away. Recent events show that the cutting edge of unmanned combat lies in the ability to build, deploy, and launch drones from inside enemy lines—or close enough to bypass early warning systems entirely. This adaptability in modern warfare is a testament to the evolving nature of military tactics.

    Covert drone operations now blur traditional lines of engagement. With new platforms hiding in forests, under civilian infrastructure, or even inside standard shipping containers, military planners are now facing a profound challenge: How do you defend against an attack that appears to come from your own backyard? 

    Anthropic said its latest artificial intelligence model resorted to blackmail when told it would be taken offline.

    In a safety test, the AI company asked Claude Opus 4 to act as an assistant to a fictional company, but then gave it access to (also fictional) emails saying that it would be replaced, and also that the engineer behind the decision was cheating on his wife. Anthropic said the model “[threatened] to reveal the affair” if the replacement went ahead.  

    Those who prepared her body carefully arranged the severed pieces to appear almost intact, placing the hand beside the forearm. 

    Archaeologists said that it seemed the goal was to make the cut-off right arm match the unusual position of her left arm, which was bent sharply, more than a right angle, and tucked in very tightly. 

    The girl's body was also carefully aligned with the setting sun on the winter solstice, and her coffin pointed toward the rising of Sirius, the brightest star in the sky.

    Experts suggest her burial may be the earliest sign of the Osiris and Isis myth, in which the goddess Isis reassembles the dismembered body of Osiris beneath the rising Sirius, symbolizing death, rebirth, and cosmic order. 

    Archaeologists have discovered a 2,500-year-old tomb in Turkey that is potentially connected to King Midas — and contains rare artifacts and cremated remains of a high-ranking individual.

    “Based on these artifacts, we estimate that the person in the tomb chamber may be a member of the royal family associated with Gordion and Midas,”  Mehmet Nuri Ersoy, the Turkish minister of culture and tourism, announced at a news conference earlier this month, Live Science reported. 

 Now, a team of Turkish researchers have uncovered dozens of clay and smoothed river rock sling stones, unearthed just outside what would have been the palace walls, along with arrowheads, charred buildings, and hastily buried human skeletons.

Together, experts say, the clues paint a chilling picture of close-range fighting and a sudden, catastrophic fall, just as the ancient Greeks described.

'This concentration of sling stones in such a small area suggests intense fighting, either a desperate defense or a full-scale assault,' said Professor Rustem Aslan of Canakkale Onsekiz Mart University, who is leading the excavation.

  •  "The Clever Folds That Kept Letters Secret"--BBC Future (via Get Pocket). Discussing "letter locking": "the technique became common throughout Europe during the Late Middle Ages (1250-1500) and Early Modern periods (1500-1815). By folding and cutting letters in various clever patterns, people attempted to hide their correspondence from unwanted readers, and the 'locks' came in myriad types." It couldn't keep someone from reading the letter, but let you know if someone had opened the letter to read it.
By at 6 comments:
Labels: , , ,

Wednesday, July 23, 2025

VIDEO: Review Of The Baofeng DM32 DMR Ham Radio for SHTF

A review of the Baofeng DM32 DMR portable radio. The video mentions that Brushbeater was having a sale on these radios, but the video description now indicates that Brushbeater is completely sold out. While not as low of a price, Amazon nevertheless is offering them for 23% off the MSRP, bringing them down to $85 apiece. The review covers the items included with the radio, and goes over the features of the radio. He notes that "this radio has more features and more options than any other low cost consumer radio that I have ever tested" and comes close to what the Motorola XTS can do. He notes that the radio is unlocked, meaning it "can transmit on some of the hams radios frequencies as well as on GMRS, MRS and LMR frequencies." It can also receive commercial FM radio, AM airband from 108 to 136 my gigahertz, VHF 136 to 174 and 220 to 260 gigahertz, UHF 350 to 390 and 400 to 520 gigahertz and NOAA weather alerts. Notably, per the review, the digital broadcasting offers encryption. 

VIDEO: "I Review The Baofeng DM32 DMR Ham Radio for SHTF"
NotaRubicon Productions (18 min.)

By at 1 comment:
Labels: , , ,

Saturday, July 12, 2025

VIDEO: Test Of Products/Methods To Block Cell Phone Signals

The author of this video tests several different Faraday bags and some other methods commonly cited as ways to block signals from your cell phone. Note that one brand of Faraday bags completely failed the various tests. Of the various other methods sometimes suggest--putting a phone in a foil lined bag chips bag, wrapping in aluminum foil, or putting it in a freezer or microwave--only the wrapping in aluminum foil worked, but it was intermittent. 

VIDEO: "How To Make Your Phone INVISIBLE To Tracking in 2025"
Business Reform (11 min.)

By at 2 comments:
Labels: ,

Thursday, June 5, 2025

Don't Plug Your Phone Into Public Charging Stations

"According to officials, hackers can 'install malware' at USB ports in a trend known as 'juice/port jacking," reports the New York Post, adding: "Cybercriminals can then ransom your device or steal your passwords." Get a portable battery pack and use it to charge your phone. 

By at 4 comments:
Labels: , ,

Tuesday, June 3, 2025

Guest Post: Zombie Apocalypse Movie Theater, Part III

Post apocalyptic improvised movie theater inside an
abandoned underground bunker. (Bing AI Image Creator
https://www.bing.com/images/create/)
 

 "Zombie Apocalypse Movie Theater, Part III" by the Realist. 

Disclaimer: All products mentioned in this article were purchased by myself. I did not receive free samples, evaluation models, or other compensation from any manufacturer or retailer. I have no formal relationship with any manufacturer or retailer mentioned in this article - I have only been an arms-length customer. All brand names and product names used in this review are the trade names, service marks, trademarks, or registered trademarks of their respective owners. Further, this article reflects my unique circumstances and subjective opinions with regard to performance and other characteristics of the products discussed. Your mileage may vary.


    After I finished my Zombie Apocalypse Movie Theater Part II article, I promised myself I would not do a part three. But, here we are.

    In the first ZAMT article, I did some hand waving about projector screens, but did not provide a lot of guidance or suggestions. Further, the one projector screen I specifically mentioned quickly became unavailable. But, I continued to pursue projector screen solutions.

    One firm rule I have decided upon for the ZAMT is that it will not be set up outdoors. It must be set up indoors, whether that be a large room in a residential or commercial building, a corner of a warehouse, a barn, or some other enclosed space. The reason for this rule is two-fold: first are the obvious security issues present in a zombie apocalypse environment, and second is the fact that a free-standing projector screen is effectively a large sail in any kind of wind. After looking at many reviews of self-supporting projector screens on Amazon, it became apparent that anything other than the mildest of breezes can be fatal to a consumer grade screen that uses a rigid frame. A gust of wind will topple the screen, and may damage its support frame.

    Companies that set up outdoor movie events usually use inflatable screens, and these companies put a lot of effort into tying down their screens so they stay put in the wind.

Why Use A Projector Screen?

    While a projector screen is not absolutely necessary, a screen will improve the viewing experience, provide a brighter image compared to an unimproved surface such as a blank wall, and provide greater flexibility in where a ZMAT can be set up.

    I became serious about projector screens after I put up an IOLIEO cloth screen (discussed below) and was astonished at how much brighter the image from a lower-power projector appeared. Even a dim twenty-dollar projector was watchable when projected on the IOLIEO projector screen in a dark room. And, I was able to project a much larger watchable image when compared to just projecting against an off-white wall.

Improvised Projector Screen Materials

    For potential screen materials, I experimented with different products, including paints, swatches from commercial screen manufacturers, white cloth, and cotton canvas, along with an off-white painted wall in my house. I found white cloth, even a thick table cloth, to be unacceptable because light passing through the cloth would reflect back from whatever was behind the cloth, harming the image quality. Paints were not as white as I had hoped, and then I was still left with the problem of what to apply the paint to when creating a projector screen.

    Quality cotton canvas has potential. It is naturally off-white and is thick enough that there is not a significant problem with light passing through the canvas and reflecting back. At the suggestion of an article I saw, I bleached the canvas to try to make it whiter. All the bleaching did was make minor variations in the cotton color more apparent - don't bleach your canvas if you want to use canvas as a screen material.

Modern Inexpensive Cloth Projector Screens

    I looked at the inexpensive cloth screens that can be attached to a frame, or stretched and attached to a wall. Most inexpensive cloth screens are somewhat translucent, with a significant amount of light from the projector passing through the fabric and reflecting back from whatever is behind the screen. (The manufacturers of these fabric screens portray being translucent as a desirable feature because you can potentially set up you projector in a rear-projection configuration.)

    I also experimented with an inexpensive ALR (anti-light reflecting) cloth screen. The coating on the cloth was very retroreflective. (Retroreflective materials, like those seen on reflective highway signs, reflect the light back to its source with minimal scattering.) Unfortunately, it had such a narrow field of view that it was practically useless. (Many people who have dedicated home theaters use an ALR screen. I expect the performance of expensive ALR screens to be much better than the cloth ALR screen I experimented with.)

    I did find a fairly inexpensive cloth screen I really liked. It has two layers sandwiched together - a thick white front layer, and a black back layer. The black backing solves the problem of light passing through the screen reflecting back. The screen I tested was made by IOLIEO (https://www.amazon.com/dp/B0D9VPRNNW), although there are a few other manufacturers offering similarly constructed cloth projector screens.

  The IOLIEO 84-inch diagonal (73"W x 41"H) cloth
screen. The top shows the screen as set up. The minor wrinkles in the lower-left
corner are not visible during use. The bottom shows a projected image from a
cheap $20 projector. The as-photographed image, filling the full 41-inch
vertical height of the screen, appears somewhat brighter in this photograph than
it was in person, but it was still quite watchable.

     With the IOLIEO screen, you still need to come up with some kind of frame for it or use hardware included in the package to attach the screen to a wall. I attached the the top of the screen to a very straight 1x2 board using large binder clips (the binder clips must be able to handle 1-inch thick material). In my case, the 1x2 board was hung from curtain rod supports using small shock cords. Then I attached the bottom of the screen to another very straight 1x2 board using binder clips, letting the board just hang. This setup worked very well. I could just as easily have suspended the screen between a couple of tripods, between a couple of step ladders, or between purpose-built supports.

Modern Inflatable Screens

    There are many consumer grade inflatable screens available. They are intended for outdoor use but can also be used indoors, and they generally have a larger screen size than is going to be available with the consumer grade free standing rigid frame screen options.

    Most consumer grade inflatable screens usually rely on a blower to keep the screen inflated. And, some blowers can be fairly noisy. (I found four exceptions on Amazon that stay inflated without continuous blower operation.) The blower consumes a lot of power - not a problem when you have access to a stable electrical grid, but a non-starter if trying to power your austere theater from a battery-based source.

    I have not done any evaluation of inflatable screens beyond looking at various models available for sale on Amazon and reading their reviews, and seeing what equipment is used by people who provide video projection services for outdoor events.

Vintage Tripod Projector Screens

    Growing up, my father had a reasonable sized tripod projector screen made by Da-Lite Screen Company. The surface of the screen was composed of very small glass beads, making the screen retroreflective. The screen was very bright because most of the light from the projector reflected back to the audience. The down side of a glass bead screen is the comparatively narrow field of view compared to matte-white screens - too far off to either side and the image will be noticeably dimmer. But, people used them for years, and as a child I don't remember the field of view being a problem.

    Glass bead retroreflective screens started being sold in the late 1920s by various manufacturers, and they continued to be manufactured until a few years ago. While glass bead screens are no longer made, there are lots of used vintage glass bead screens available through various used marketplaces. The most common size is 40-inches by 40-inches - small by current standards, but still quite serviceable in an improvised austere movie theater environment.

    Many vintage projector screens were also manufactured with a reflective silvery surface material (probably aluminum paint). I have not experimented with that type of screen, so I cannot offer an opinion on its performance.

    Vintage tripod screens are fairly easy to set up, and are fairly robust if not abused.

Modern Tripod Projector Screens

    There are a few modern consumer grade tripod screens being sold. Their quality is questionable. I purchased one that had four arms that attached to a center plastic hub at the top of the tripod mast. The individual arms were held in place with easy to lose screws. The ends of the arms then connected to grommets in the corners of the screen. The actual screen material was very nice - a thickened mat with a matte-white surface. I was disappointed that the tripod and support structure was so poor in quality.

    My one sample does not give me any confidence that there are reasonably priced quality modern consumer grade tripod screens. I am sure the much more expensive tripod screens for business or institutional use would be higher quality. 

 Pop-up screens with a 4:3 aspect ratio. From front to
back, the Grandview 50-inch, Da-Lite 60-inch, 80-inch, and 100-inch diagonal
screens. The screens closed and stowed shown at the bottom. A tape measure
extended to 36 inches is provided for scale.

Modern Pop-Up Projector Screens

    I stumbled across the Da-Lite Deluxe Insta-Theater product line while searching for vintage Da-Lite screens on ebay. Unfortunately, the Insta-Theater is no longer being made by Da-Lite. The Insta-Theater can easily be set up in less than a minute - rotate the two support feet perpendicular to the screen case, open the screen case, grasp the handle in the center top of the screen and start lifting. Once lifted to near full height, the screen will support itself and stay in place. Take down is equally quick and simple. The Da-Lite Deluxe Insta-Theater has a matte-white screen surface. They were made in 60, 80, and 100 inch diagonal sizes in a 4:3 aspect ratio, and 73 and 90 inch diagonal sizes in a 16:9 aspect ratio.

    Kodak sells a pop-up screen very similar to the Da-Lite screen. (https://www.kodakphotoplus.com/products/kodak-instant-cinema-100-pull-up-projection-screen) This screen is 100-inches diagonal with a 16:9 aspect ratio. Reviews indicate the Kodak screen is not as durable as the Da-Lite equivalent. The latches that hold the lid closed are poor quality necessitating the use of shock cords or straps to make sure it stays closed while being carried. My screen arrived with a couple sheered off pop-rivets that held a lid hinge - I blame rough handling by the shipping company. New pop-rivets solved that problem.

    Grandview sells a table-top 50-inch diagonal screen, with a 4:3 aspect ratio, functionally similar to the Da-Lite Insta-Theater (https://grandviewscreen.com/screen/detail/27). Grandview also sells larger pop-up screens that sit on the floor.

    There are other manufacturers that sell functionally similar pop-up projector screens, but I have not had an opportunity to examine them.

     The pop-up projector screens I have examined all have a matte white screen surface. Matte white is a fairly efficient surface while offering a wide field of view.

    In general, I like the pop-up screen concept. They are very portable, set up quickly, and are self contained with no parts to misplace. However, they are somewhat fragile and will not handle abuse. And, they can be bulky, with the case for the 100-inch Kodak screen being over 92 inches (7.7 feet) long.

Buying A Projector Screen

    As you may have noticed, many of the projector screen options I discussed are no longer manufactured. If you go the discontinued/vintage route, you will be forced to rely on the used markets, such as ebay or Facebook Marketplace. Don't be afraid to talk to friends, too. A friend gave me a vintage tripod screen that was collecting dust in the back of his garage.

    For new screens, there is always Amazon and ebay. ProjectorScreen.com (https://www.projectorscreen.com/) has an amazing selection of projector screens. Many of the on-line camera/photography supply companies also sell projector screens.

Observations

    Based on my subjective observations, there is little difference in performance between a modern matte white projector screen, a vintage glass bead projector screen or the IOLIEO double-layer cloth projector screen. They are all superior to an as-found surface such as an off-white painted wall or translucent white fabric.

    The materials used to make my vintage glass bead screen have yellowed slightly due to age - I'm guessing it was made sometime in the 1960s. However, the performance lost to aging materials is mitigated by the retroreflective nature of the glass bead screen.

Conclusion

    My objective with these ZMAT articles has been to identify equipment that can be set up and used in an austere environment where power to operate the equipment must come from a constrained source such as a battery-powered power station.

    This article focused exclusively on portable projector screens. While evaluating different projector screen options, I developed a definite preference for the modern pop-up screens manufactured by Da-Lite and other manufacturers.

    A quality projector screen can dramatically improve the viewing experience of your austere movie theater and will help you get the most out of your projector. A portable projector screen provides greater flexibility in where an austere movie theater can be set up since you are not dependent on finding a wall with a suitable surface to use as an improvised screen.

---

Resources:

    This YouTuber provides good reviews of video projectors and projector screens. He uses uses test equipment to objectively measure performance characteristics of the projectors and screens being reviewed. His focus is the home theater, but he also reviews portable video projectors.
https://www.youtube.com/playlist?list=PL-51DG-VULPpwjbD2A9U0ekk4g6D1Hhnb

    This article explains why projector lumen output matters, and provides recommended lumen output ranges for various environments. I personally think their recommendations, based on my own observations with my equipment being used in a dark room, are a little high. But, their recommendations provide a starting point in analyzing needs.
https://www.projectorscreen.com/blog/How-Many-Lumens-Do-I-Need-For-A-Projector

By at No comments:
Labels: , ,

Sunday, May 4, 2025

Post-Collapse Computer Network

The Survival Blog recently published a couple series of articles on setting up computer networks for post SHTF situations, including one offering up a simpler option. If this looks familiar, it is because it was included in one of my recent "Guns & Prepping News" post taken down by Google:

  • "A Simplified Disaster Network" (Part 1) (Part 2)--Survival Blog. The author explains:

Having an operational computer network running in a post-SHTF world may seem frivolous to some people. But if you have any plans to use computers, tablets, or cell phones as part of your post-disaster operations, it can provide the capability for those devices to communicate, share data and synchronize their activities. It can also provide some support for important things like WiFi security cameras and WiFi sensor monitoring.

The author had previously authored a series of articles on how to set up a mobile WiFi/Ethernet network. But he had some people complain it was too complicated and whether there was a simpler alternative. These two articles offer that simpler alternative. The first article goes over hardware and configuration. The second article goes over synchronizing files and "packaging" of all of the equipment to make it portable, along with some odds and ends.

By at No comments:
Labels: , ,

Sunday, March 23, 2025

Gun & Prepping News #25

Some articles that have caught my attention:

     The problem is that being fast doesn't matter much, because the bad guy decides when to attack and strives to ensures that you have no warning.  So, it's a surprise attack, unless your situational awareness is very good; in which case you've given away the fact that you are aware of the impending attack; in which case the attack never occurs, because the bad guy isn't stupid.  And then again, some people are stupid.

This was on of his comments to "The Complete Concealed Carry Training Guide" from Alien Gear Holster. The guide is an outline intended "[t]o go from newly minted concealed carrier with ZERO experience with a pistol (outside of the average state-mandated CCW course) to a reasonably competent and prepared concealed carrier." The guide emphasizes that it is only to provide a basic set of skills in preparation for further development; adding that "[n]o training course in existence will guarantee success in combat. You can only hope to increase your level of preparedness to the point where your instincts are more reflexive and routine." This appears to be taken from a larger document or has taken from several other documents because it literally cuts off mid-sentence.

    And something else to keep in mind:

     What happens if you haven't practiced recently?  

     You will be shot to death, because you could not get your pistol out of your holster.  When I was in training to be a security officer to guard federal facilities in the Middle Tennessee area, we viewed a video of an attack on a federal building.  The security officer in the video was behind cover, but could not get her pistol out of her holster because the snap on the strap that held the pistol in the holster had rusted and was stuck.  She had not taken her pistol out of her holster since last qualification about a year before.  So the bad guy walks around the counter and shoots her. 

A lot more linkage and advice, so be sure to check out the whole thing.

  •  Also be sure to click over to Greg Ellifritz's most recent Weekend Knowledge Dump. Some of the articles that I found more notable were a set of four articles on flexible impact weapons; "A Hard Look In The Mirror" which is a good reminder that handguns are defensive first aid kits, but the rifle is still king of the defensive weapons; a link to an article on how to be someone people love to talk to together with Greg's comment that most of us would be better off learning more interpersonal skills over improving our draw speed; an article from Recoil on staying safe when visiting a city, most of which is the "don't do stupid things, in stupid places, as stupid times"; an article on point shooting; one on using silcock keys for urban survival; an article examining why the U.S. has higher murder rates than most other industrialized countries; and more.
  • "The Evolution of the Battle Rifle: From the FAL to Today’s AR-10"--Ammo Land. This is a strange article in my mind because it treats the FAL, M-14, and AR-10 as coming from different eras, whereas they were all developed at roughly the same time and competed against each other in the U.S. weapon's trial. If there is one thing that ties all these weapons together, it is the Army's obsession with having "do it all" equipment that isn't very good at any task. In this case, wanting a rifle that could replace the M-1 carbine as a personal defense weapon, provide the suppressive fire of an assault rifle, but still provide accurate and powerful fire out past 500 yards.
  • "Converting S&W J-Frame Combat Grips to Boot Grips"--Revolver Guy. A "how to" on converting some larger J-frame grips to be more concealable. The problem the author was trying to solve was getting some grips for a J-frame snubby that were thicker and covered the backstrap of the frame to better fit his hands.
  • "PSA AK-47 GF3 Review: The Best Budget AK?"--The Truth About Guns. No specific MSRP given in the review, but it states that the weapons will be in the $600 to $700 range. The main points of this model over some other lower cost copies that have been sold are "[t]he hammer-forged bolt, carrier, and front trunnion." Apparently other offerings from U.S. manufacturers have suffered from softer trunnions that have worn out. The author complains a bit that the barrel is a nitride treated barrel rather than chrome lined, but I think the nitride barrel will probably have as good or better wear over the long run.
  • "PAIN!"--Straightforward in a Crooked World. An excerpt:

    Our conversation had started with me asking “So who shot you in the throat?”, a basic conclusion on my part, because on one side of his throat he had a very small round scar, on the other side, a jagged dime sized scar, accompanied by a damaged voice. It had the hall marks of a twenty-two caliber wound and this had peaked my interest. He was an ex-convict and career criminal, who had spent part of that career as a car jacker in the late 1980s and 1990s. He had a rather successful run (according to him) until he went from car-jacker to attempted to car-jacker. As we sat and talked in his now paroled and work released based probation he explained the scenario that led to his down fall.

"I'm 6'2", and I had a big old revolver that took .44s. You look down that barrel and you think, 'take what you want, please don't kill me with that thing. But not this one guy. I stuck the gun in his face yelling for him to get out of the car, and as he is sliding out I hear the little 'pop' sound. I kinda saw his hand coming up, but my mind was all focused on his face and my gun in his face, and I couldn’t really see much else. So I hear this 'pop' and, next thing I know I feel like I'm gonna throw up or something. I can't talk right and I spat blood all over the place. I didn't know what happened. I'm looking around, but I see blood all over me, and I can't breathe. I'm trying to get out the passenger side of the car, but it's not my car and it was like being in a nightmare. I couldn't find the door handle, and all I know is everything is going bad. I'm thinking 'I don't want to go to jail! I don't want to die!' I get the car door open and fall out on the ground and stumble all over. I'm spitting blood. I'm scared out of my mind. I can't see anything. Turns out, he shot me with this little .22 derringer. This told me two things: 1) That dude had that planned out what he would do. He had this little nothing gun and was ready to go if he had to. 2) I had this big gun and didn't think I had to do anything other than stick in someone's face. I was wrong about that.”.

  • "Galco Executive Shoulder Holster"--Bond Lifestyle. A look at the shoulder holster used for James Bond's Walther PPK in the movies GoldenEye, Tomorrow Never Dies, and The World Is Not Enough. Unlike more modern holsters that counterbalance the weapon with magazine or speed loader pouches, this simply has a strap that goes around the shoulder and apparently clips on the waistline of the pants. But it looks like it would, for that reason, be less bulky and more concealable. It does not appear to be manufactured by any longer by Galco--at least, it doesn't show up on the Galco website. 
  • "Thinking Straight — or Just Trying to Think?"--Tactical Wire.

    First we’ll examine the whole “gun = security” thing. Guns don’t provide that, it’s the attitude, the mindset, the whole outlook on life. Guns are tools that (like surveillance gear for example) can make security more attainable – but being armed doesn’t do it alone.

    “Owning a handgun doesn't make you armed any more than owning a guitar makes you a musician." – Jeff Cooper. But, being armed is not nothing; also from Jeff Cooper, "Remember the first rule of gunfighting ... have a gun." 

    Now we don’t wander about in public armed because we want a fight. We’re armed in the event the fight comes to us and we can’t decamp in an efficient, orderly military manner. The gun doesn’t make us safe. 

  • "Negative Outcome – Chasing and Shooting"--Tactical Professor. Man arrested after he chased down a would be car burglar attempting to flee the scene and shot the bastard. Unfortunately for the shooter, chasing a criminal down in order to shoot him is not "self defense."
  • "Five minute project: DIY Cat Eyes"--Bad Lands Field Craft.  "Cat eyes" in the context of this article are strips of luminescent material attached to the back of a helmet, hat, or pack that allow someone behind you to more easily follow you in the dark. You probably shouldn't be hiking in the dark, but you never know. 
  • "Would Prepping by Recipe Work for You?"--Organic Prepper. 

    There are as many ways to prep as there are preppers. Stockpiling longterm stuff you find on sale, buying buckets of freeze-dried food, preserving your own… The list could go on and on. But, have you tried “prepping by recipe?”

    The concept is exactly what it sounds like. You choose some of your family’s favorite meals, and then you create a way to serve that dish made only with long-term food. In my opinion, these meals are far more tasty and welcome than adding water to fettuccine alfredo from a bucket.

* * *

 How do you build this kind of stockpile?

Start by listing your family’s favorite meals. Go with five suppers and two breakfasts to begin.

  •     Spaghetti and meat sauce
  •     Stir-fried pork and broccoli with rice
  •     Vegetable beef soup
  •     Mexican burrito bowl with meat, veggies, and rice, topped with cheese sauce
  •     Chicken pot pie with canned veggies and biscuit topping

Some breakfast ideas might be:

  •     Hashbrowns with onions and peppers, scrambled eggs, and a slice of fried spam
  •     Oatmeal with fruit, cinnamon, sugar, and whole milk
    Here’s my suggestion: Think of it in terms of categories such as security, food, water, and shelter (your home and property). Examine each category and consider items with embedded electronics that may be especially important or critical to you during post-EMP SHTF. Think of backups for critical survival infrastructure.

    Another side note… It can become expensive to store certain electronic items, backups, and spares in a Faraday cage because they’re not readily available, especially if stored in a sealed galvanized garbage can (for example). However, for those who cannot afford this for everything, put in a Faraday cage and consider storing those high-cost items there while you’re not using them. This is where professionally designed EMP bags come in handy for much easier access.

 To protect our essential electronics from an EMP event, we should take the following steps:

  •     Disconnect electronics: During an EMP event, disconnect our electronics from the electrical grid to prevent them from getting damaged.
  •     Wrap electronics in protective cloth: Wrapping our electronics in a protective cloth can provide an additional layer of protection against EMPs.
  •     Use EMP-proof electronics: Investing in EMP-proof electronics can be an effective way to protect our essential electronics. Vintage electronics are often more resistant to EMPs as they were built before the widespread use of microelectronics.
  •     Use surge protectors: Installing surge protectors can help protect our electronics from power surges caused by EMPs.

Some of the essential electronics that we should protect during an EMP event include radios, cell phones, glucometers, inverters, pumps, and dehydrators. These devices can be crucial for our survival during an emergency.

  • "The Superior Hat"--Blue Collar Prepping. A review of the "Men's Superior Hat" from Duluth Trading Co. This is a heavy duty hat, insulated hat with a deep brim on the front and flaps that can be folded down to cover the ears. The advantage of a brimmed hat isn't just shade: for those who wear glasses, the brim keeps rain or snow off the glasses; and if you don a hood, it keep the hood from falling down over your face. 
By at No comments:
Labels: , , , ,

Sunday, October 27, 2024

The Realist: Zombie Apocalypse Movie Theater, Part II

 A guest post from the Realist.


Post apocalyptic movie theater set up inside an
abandoned warehouse. (Midjourney AI Image Creator)

Disclaimer: All products mentioned in this article were purchased by myself. I did not receive free samples, evaluation models, or other compensation from any manufacturer or retailer. I have no formal relationship with any manufacturer or retailer mentioned in this article - I have only been an arms-length customer. All brand names and product names used in this review are the trade names, service marks, trademarks, or registered trademarks of their respective owners. Further, this article reflects my unique circumstances and subjective opinions with regard to performance and other characteristics of the products discussed. Your mileage may vary.

    As I said at the close of the first Zombie Apocalypse Movie Theater (ZAMT) article: "The equipment described above is just a snapshot of my current equipment configuration. I expect that equipment mix to continue to evolve." That equipment mix has evolved, and I have shifted my focus to trying to simplify the setup of a portable theater for austere environments.

    My research has continued, including looking at several more projectors, and looking at utilizing Bluetooth speaker systems with built-in amplifiers to achieve a wireless or nearly wireless movie theater setup.

Cheap Projectors

    I continued to look at cheap projectors just to see what the minimum capabilities might be. Besides the ultra cheap (YG300, 360x240 resolution) twenty dollar projectors (sometimes over $50 on Amazon), I looked at other projectors that were around thirty-five dollars each.

    Only one of the cheap projectors, the Besus "J19 Mini Projector" with 480x360 resolution did not disappoint me. The slightly higher native resolution made a big difference in perceived picture quality. With a vertical resolution of 360 pixels (360P), the picture didn't seem pixelated like it does on lower resolution projectors. The 360P specification will become important later in this article.

    Overall, my opinion about cheap projectors remains unchanged: avoid the cheap projectors. Their quality seems spotty, and even when they work properly, they have very limited performance.

Anker Nebula Mars 3 (left), ETOE D2 EVO (center), and
Kodak LUMA 75 (right) projectors. 12 ounce soft drink can for scale.

Anker Nebula Mars 3 Projector

    The Anker Nebula Mars 3 projector is my current best projector. It is a 1000 ANSI lumen DLP portable HD (1920x1080 native resolution) projector. It has a fairly large 185 Wh built-in battery, allowing it to run for several hours on battery power. It has built-in speakers driven by a claimed 40 watt amplifier.

    The Mars 3 runs Android and has WiFi and limited Bluetooth connectivity. It can operate as a Bluetooth speaker (e.g. paired with your smart phone to play music), but it cannot use Bluetooth to transmit audio to a separate Bluetooth speaker.

    In my very brief light measurement session, I did not obtained an ANSI lumen number I trusted. The projector was so bright, there was significant light reflection off various room surfaces that biased up the light measurements I was taking. But, I have no doubt it outputs 1000 ANSI lumens in its brightest operating mode.

    The Mars 3 is fairly large (6.3 x 10.2 x 9.8 inches), with its smallest dimension being 6.3 inches. I wanted a hard case to protect it, but it is too thick to fit in any of the inexpensive Chinese hard cases, so I ended up spending a fair amount of money on a genuine Pelican case. (For a lot less money, I probably could have purchased a large surplus ammo can and lined it with foam rubber to protect the Mars 3.)

    I am annoyed that the Mars 3 cannot use Bluetooth to connect to external speakers.

Kodak LUMA 75 DLP Projector

    I purchased this projector as more of a novelty - an almost shirt-pocket sized projector. It is a 57 ANSI Lumen (my measurement) portable projector with a native resolution of 640x360 (360P). It measures 3.5 x 3.5 x 0.9 inches in size. It has a built-in battery that is claimed to operate the projector for two hours. It has one small speaker, driven by a claimed 1.5 Watt amplifier. The projector is charged using a 5 VDC USB-C cable, and can operate from an external USB power source. It did not come with a remote control.

    Due to its size, the LUMA 75, is a very basic projector. Navigation of its simple user interface and volume adjustment is accomplished via five touch buttons on the top surface of the projector. Focus is adjusted using a thumb wheel on the side of the projector. There is no keystone adjustment. It can play video via an HDMI cable, or play movies stored on a USB flash drive.

    The LUMA 75 does handle various aspect ratios I have tested (4:3, 16:9, 2.35:1) properly.

    With only 57 lumens of light output, maximum usable screen size will be limited. An online calculator that calculates screen brightness based on screen size and projector light output recommends a screen size no larger than 36 inches diagonal for acceptable brightness (15 foot-Lamberts) in a completely dark room. I was personally testing the projector with a diagonal screen size of 48 inches (8.3 foot-Lamberts), and thought it was acceptably bright.

    For its diminutive size, I really like this projector.

ETOE D2 EVO Projector

    I have been interested in a "sealed light engine" LCD projector, which is claimed to be dust proof, since learning such a thing existed. But, their prices typically start at around $150. I found the ETOE D2 EVO projector on TEMU for $84 - apparently, a clearance price. (The updated ETOE D2 EVO Pro is available on Amazon for more than I think it is worth)

    It is fairly compact with dimensions of 4.45 x 5.31 x 5.83 inches, and weighs a modest 3.6 pounds. The D2 EVO runs Android and has WiFi and Bluetooth connectivity.

    It has a claimed 400 ANSI lumen output, but I measured more like 157 ANSI lumens. Even with the light output being less than half what the manufacturer claims, it seemed fairly bright for such a compact transmissive LCD projector.

    Especially for the price, I really like this little projector. It has a bright sharp (after focusing) image, with the corners being less soft than I've seen before in transmissive LCD projectors. I like the dust proof "sealed light engine", which could be a very important feature in a post-apocalyptic scenario were filtered clean indoor air may no longer be common.

    One downside of this projector, which I am seeing on a lot of other projectors, is that the projector itself only has a power button. It is unusable without its remote control.

Monster X6 (left), ECOXGEAR Boulder Max Pro (right), and
Zealot S49 (bottom center) Bluetooth speakers. 12 ounce soft drink can for scale.

Bluetooth Speakers

    Sometime after I finished the first ZAMT article, I started looking at portable amplified speakers to reduce setup complexity. Again, like everything else, manufacturer specifications are exaggerated.

    The Bluetooth amplified speakers I have looked at are monophonic - they take the stereo signal, combine it into a single audio channel, and amplify that signal. Of course, you can always directly plug an audio cable into the speaker to use it as a standard amplified speaker, but that kind of defeats the purpose of having Bluetooth speakers. There are Bluetooth speakers that can be set up to be left or right channel for stereo sound, but I have not experimented with any of those speakers.

    I first experimented with some inexpensive Bluetooth speakers (Zealot S49) that were only a little bigger than a soft drink can. The manufacturer claimed these speakers had 20 watts output, but I seriously doubt it - a half watt is probably closer to the truth. They sounded muddy and were not as loud as I hoped.

Monster X6 Speakers

    I was first exposed to the Monster X6 speakers at my employer's "all hands" meeting held in a large warehouse-like building. But for the horrible acoustics (echo, combined with the speakers sitting on the floor), they would have been adequate for the room that was seating several hundred people.

    A couple weeks later, I saw the Monster X6 speakers on sale at Sam's Club. They are a PA and Bluetooth "Party Speaker". I bought a pair and brought them home. They claimed to output up to 600 watts. They have Bluetooth in addition to an amazing number of wired connectivity options. They require 120 VAC. Each speaker came with a tripod stand and an inexpensive microphone. These speakers also have a pair of wheels and an extendable handle so they can be pulled like a rolling suit case.

    What makes them a "Party Speaker" is that they have a bunch of LEDs on the sides of the front grill and around the woofer that will light and change color to the music being played - cute for a party, but annoying in a theater environment.

    In testing, I overheated them - but fortunately didn't kill them. Just before I shut them down because I was smelling something overheating, the pair were drawing 150 watts - 75 watts for each speaker. No, they were not 600 watt speakers, although they were really loud (I was wearing the hearing protection I would wear when shooting at an indoor range).

    The Monster X6 speakers are really big (27.5 x 20.5 x 12.0 inches, 38.8 lbs. not including the stand), so I started looking for smaller Bluetooth speakers, but not too small.

ECOXGEAR Boulder Max Pro Speakers

    Again at Sam's Club, I came across ECOXGEAR Boulder Max Pro speakers on sale. While they are still large-ish, they are much smaller (15.5 x 11.4 x 19.8 inches, 30.8 lbs.) than the Monster speakers. The ECOXGEAR speakers are Bluetooth "party" speakers, they are IP67 waterproof (their marketing videos show the speakers floating down a stream), and they are battery powered (7 AH 13.8 volt lead-acid rechargeable). All external jacks (120 VAC, audio-in, microphone, USB) are behind fairly substantial waterproof covers. 120 VAC is required to recharge the built-in battery, and of course, the speakers can run off 120 VAC. The manufacturer claims they output up to 100 watts - I doubt it. These speakers also have a pair of wheels and an extendable handle.

Wireless Speaker Latency

    Audio latency between the projector and wireless Bluetooth connected speakers turned out to be a much bigger problem than anticipated. Audio latency is observed as audio and visual events (e.g. speaking lip movement, sharp noises) in the movie not being synchronized.

    I expected to observe some Bluetooth speaker latency, but it was more noticeable than expected. I observed an estimated latency of around 200 milliseconds (one-fifth of a second). This 200 ms latency observation is consistent with what I expected from my reading on the subject.

    Then I had a bright idea to try using a small analog FM transmitter. These FM transmitters used to be very common in the era where most vehicles only had an AM/FM radio, and there was no other way to connect an audio source (e.g. MP3 player) to the vehicle's audio system. The FM transmitter plugs into the earphone jack of the audio source and transmits a weak short range signal that can be picked up by a nearby FM radio.

    The FM transmitter worked beautifully (no audio latency) when I was picking up its signal using an analog FM radio. However, when I used the built-in FM receiver of the party speakers, I observed a latency of 480 milliseconds (almost one-half of a second) - this was completely unexpected and completely unacceptable.

    Some projectors have audio latency adjustments, but I have not seen that capability on the low cost projectors. The Mars 3 projector, which lacks Bluetooth transmit capability, has a latency adjustment - up to 250 milliseconds.

Dealing With Audio Latency

    There are several ways of dealing with the audio latency:

    (1) Ignore it. Much of the time, the 200 ms Bluetooth latency shouldn't be a serious distraction.

    (2) Try to adjust it out or minimize it if the projector has a latency adjustment.

    (3) Run an audio cable from the audio output (headphone jack) of the projector to the amplified speaker or speakers. (This still reduces complexity over using a separate audio amplifier as I did in the first ZAMT article.)

    (4) Use analog FM radios to receive the audio from the FM transmitter, then connect those radios, via their headphone jack, to the amplified speakers. But, this increases setup complexity.

    The analog FM transmitter I experimented with was the Scosche FMT7-SP1 FM transmitter, which was around ten dollars. It is fairly small, powered by two AAA cells, with an attached six-inch cable with a 3.5 mm stereo plug to be plugged into a headphone jack. To get acceptable performance, this analog FM transmitter must be coupled with an analog FM receiver to eliminate latency.

    (5) Use a special purpose low-latency Bluetooth wireless audio transmitter/receiver set. These require a short cable for the required 5 VDC power, and a short cable for audio. This option has simpler setup than using analog FM radios, since no tuning of radios is required.

    I purchased a special purpose low-latency Bluetooth wireless audio transmitter/receiver set that had a claimed 20 millisecond latency. In practice, the latency was imperceptible. The receivers can be powered from the USB port built into the speakers. The transmitter can similarly be powered by the projector if you have a spare USB port.

Media Player

    The media player discussion of my first ZAMT article still applies. DVD and Blu-ray disc players, USB flash drives loaded with movies, along with any other video source you might have available are all valid options.

    I've noticed that with the NEBULA Mars 3, Kodak LUMA 75, and ETOE D2 EVO, a composite video input has been omitted. However, inexpensive composite-to-HDMI video converters are available if needed, and they work fairly well. These converters need 5 VDC, and the projector's USB plug can provide the necessary power for the converter. These converters tend to run a bit warm, which may reduce operational life - they are cheap, get two.

Almost Completely Wireless Theater

    With a battery powered projector (with a short patch cord to a Bluetooth transmitter), battery powered Bluetooth speakers, and movies loaded on a USB flash drive, it is possible to have an almost completely wireless improvised movie theater.

    Of course, I could always rely on the built-in speakers of the battery powered Mars 3 or battery powered Kodak LUMA 75 with movies stored on a USB flash drive to be completely wireless.

    In most scenarios, electrical power, even if provided by a power station, will still be needed to run the major components. Battery powered Blu-ray players are rare and expensive, so a Blu-ray player will most likely be powered by 120 VAC. Further, having a battery powered projector and speakers does not obviate the need for a reliable power source - those battery powered components will need to be recharged after use.

Conclusion

    Even before a zombie apocalypse, there are many circumstances where a semi-portable movie theater that can operate "off grid" would be desirable.

    I set out to assemble an entirely wireless movie theater, but quickly discovered that being entirely wireless was impractical. Bluetooth audio latency turned out to be a worse problem than expected, so I explored several alternatives to minimize audio latency while also minimizing setup complexity.

---

Resources:

By at No comments:
Labels: , ,
Subscribe to: Comments (Atom)

Vox Day: The Exhaustion Timeline

Vox Day has run some calculations of the number of interceptor missiles have been expended so far in this latest round of war with Iran and ...