Because of the sheer length of the radio waves in certain bands, portable antennas or antennas in low space/stealth applications use a number of tricks or compromises to get resonance and radiating power sufficient to make contacts. Two of these tricks and compromises used with vertical antennas are Loading and Ground Radials. Loading: Loading is …
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I really love DIY projects and proof of concepts with electricity and radio so when I saw this little project using soda cans, cardboard, copper wire, sand, and saltwater to build a battery, I was all over it. (video from rumble.com, an alternative to YouTube’s increasingly anti-free speech platform) Instructions: Cut the tops off of …
Some appliances or components like solar inverters can trigger circuit protection to kick in when they care first connected. The reason is that often they have large capacitors inside that can really spike current use while they are charging up on start-up. In the video below, the Great Scott YouTube user, an electrical engineer from …
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Getting a very late start in electronics – I started at 50 years old! — has it’s problems that I need to work really hard to resolve. My friends tell me I always jump in at the deep end of the pool, and I think they are right. After all, I am always teaching myself …
Continue reading “How To Test Transistors with a Digital Multimeter”
3D printers are all the rage these days, and are coming down in price gradually, but are still a bit out of reach for many. So many capable electronics and maker hobbyists have turned to re-purposing all sorts of things to build their own 3D Printers on the cheap. Here’s one great example (though he …
Recently I finished building my first portable power box in an “ammo can”, and have been charging phones and testing radios with it. However… now it’s time to top the battery off, so I’m upgrading the box with a charge controller, and external port to plug in a solar panel. Here’s the video tutorial I’m …
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In this tutorial video from Car Groves, you’ll learn how to rejuvenate a dead lead acid battery by using Epsom salts to get rid of the scale that builds up on the battery plates over time. This is a bit time consuming, but good to know in case the civilized world goes boom and you …
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There’s a guy named Jehu Garcia in California who’s made it his mission to recycle laptop and other batteries in the United States instead of sending them back to China. One of his ongoing projects is building DIY power walls (similar to the commercial ones made by Tesla at a premium price) using these reclaimed …
Continue reading “Powerwall Battery Pack Construction with BMS”
Baluns and UnUns come up frequently when discussing antennas of different types and matching feed point impedance so you don’t burn up the final stage transistors in your expensive radio. This video contains one of the best explanations I’ve seen so far of wave propagation in antennas, and how to build a transformer to convert …
Continue reading “Antenna Theory – UnUn Transformers for Impedance Matching”
Decibels have never really made a lot of sense to me, though I memorized the relevant numbers to pass both my Technician and General class ham radio operator license tests. I mean, 3dB = 2:1, 6dB = 3:1 and 10dB = 10:1? What sense does that make? And its bothered me that I didn’t know …
