SCA decoder
Follow-up: I have no idea if this thing works - i tried it out, but either it's dead, or none of my local FM stations carry SCA signals! Oh well, on to some other projects!
SCA decoder | |
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I bought a circuit board, with parts already installed, from the SCA Radio Shop for only $12 (shipping included) and put it in a fancy case. The device decodes hidden signals that are sent along with some FM stations that contain muzak or other services used by malls, restaurants, etc. The face plate was cut from a tin lid. I make clear labels (like the one used on this project & the next) by printing on clear CD label stock. The "AE" logo is my design, for "Allen Electronics", an enterprise I started (half-jokingly) when I was a kid. Follow-up: I have no idea if this thing works - i tried it out, but either it's dead, or none of my local FM stations carry SCA signals! Oh well, on to some other projects! |
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Audio isolation transformer | ||
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I get interference when i connect my laptop to my amateur radio transceiver (getting ready to try using some digital modes on the air), so i built this device in hopes of isolating the units & reducing the interference. I didn't have any non-conductive washers that would fit correctly (to isolate the grounded portions of the jacks), so fashioned some from bicycle inner tube rubber! Follow-up: Unfortunately, in testing this device out, I discovered that the amplitude of the audio signal is reduced significantly, and the frequency response is rather poor. I'll give it a try anyway, but I'll probably be looking for a plan for a superior unit. |
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Ultrasonic transducer | ||
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I assembled the Ultra-RX1 from a kit (from Midnight Science). It renders sounds that are above the range of human hearing audible, so that you can listen to bats, insects, dog whistles, etc. I enjoy building & collecting equipment that allows me to directly observe things that we cannot normally detect with our senses (such as radio waves, ultraviolet light, radiation, etc.). Another thing I like about this kit is that after every few steps, it teaches you how to use electronic test equipment (like an oscilloscope) to probe the thing and make sure it's working correctly. Follow-up: This thing works great! I've heard lots of things, but there seems to be a shortage of bats around here - i fear the White-Nose Syndrome may have taken its toll locally :( |
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Aircraft receiver | ||
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This one's another work in progress - actually a two-in-one project. I recently picked up this old AM/FM transistor radio, and plan to use it to build both a metal detector and aircraft radio receiver. As detailed on several sites, the AM portion can be combined with a calculator to make a crude metal detector - something I've never tried before. I also plan to adjust the FM circuit to receive aircraft radio transmissions (something I did successfully several times as a kid by tweaking some coils on the inside). Follow-up: When I opened it up I discovered that the components I needed to adjust for the FM project were on the wrong side of the circuit board. To access them would require removing the board; but one of the hold-down screws is underneath a dial-cord assembly, which (from past experience) are pains-in-the-butts to get back together correctly once they've been disassembled. So I gave up on the FM project & tried the metal detector project. My calculator induces sound into the radio, but it doesn't alter when in proximity to metal. Oh well, not every project is successful! |
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Vintage amateur radio equipment | |
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I saved a pile of vintage amateur radio equipment from being tossed in a dumpster (a small subset is pictured at left). Follow-up: Most of it is sold off, but i still have a couple of items left on my sale page. |
Radio frequency preamplifier | |
| We needed a case built for a Miteq preamplifier assembly, so i built this one (including a logo downloaded from their site and printed on clear sticker stock). After discovering that it required more cooling than the heat sink called for in the specs, i installed the fan on the right, and even included a fan filter on the opposite side (not visible). |
The adapter for my camera card was originally encased in a hideous hinged plastic thing; i decided to extract the innards and encase them in wood instead. Marie suggested the copper side trim to make it look more steam-punk, a fashion we've been intrigued with after seeing the movie Metropolis a few months ago.
Cat's whisker detector | |
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This is my reproduction of an early 20th-century cat's whisker detector. These devices, used before the advent of tubes to detect radio signals, were an essential component of early crystal radios. I am currently building an early-style crystal radio and hope this detector actually works! The chunk of mineral on the left is galena, which i obtained last summer at the local gem & mineral show. The metal parts are faucet fixture pieces from the local Home Depot. Follow-up: It may have looked cool, but my cat's whisker didn't work. Take-home lesson: can't use substandard parts to build a technological device! |
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