power supply restoration

I’ve been very busy at work lately and haven’t had the time or energy to work on much, but I did pull out an ancient power supply from my pile of junk that I wanted to investigate. The whole thing was rusty and full of years of dirt, goo, and assorted crud. I wasn’t sure if the transformers or caps were shot, but I liked the look of it and figured it would make a cool enclosure for something else if I couldn’t get it working.

circuit construction techniques

A while back, I built a desktop cnc machine with the intent of milling circuit boards. Well, I finally got around to playing with it. The spindle is just a cheap rotary tool with one of the drill bits that came with it. I really need to get and end mill bit. The drill bit skips around a bit, but it does work. Below is a photo of the first run and the end result.

baofeng aprs ptt controller

I’ve been fiddling with some aprs ptt circuits for baofeng hand-helds for a while now. My original goal was to hook up a raspberry pi with a gps module in my car. I’d run direwolf on the pi and connect it to a cheap baofeng radio. My first attempt was basically this circuit. Baofeng radios trigger the ptt by shorting the sleeves of the two audio connectors. I isolated the audio lines with two audio transformers and set up the pi to trigger the transistor with a GPIO pin.

esr meter

Another piece of test gear that I’ve been needing for a while is an ESR meter. W2AEW has a video on his youtube channel about a simple 5 transistor ESR meter that was designed by an eevblog forum user. I had everything I needed to build it except for a 50uA meter, but ebay had plenty for a few bucks. The schematic is below, but I’d really suggest watching W2AEW’s video where he walks through the circuit and explains it in detail.

20m dipole upgrade

I haven’t posted much in the last month or so, but I have been working on a few projects. One of them involves the 20 meter band and my quick attic antenna wasn’t cutting it, so I put together a new one made from speaker wire. I wound a proper balun on an FT240-43 and connected one end to the coax running down through the wall. I used some electric fence insulators for the ends and I strung it up in the attic.

guitar stompbox

I used to play the guitar a lot when I was younger, but haven’t done much since my kids were born. I recently pulled out all of my gear and thought it might be fun to try to make my own effects pedal. I came across an article on building your own stompboxes and thought I’d give it a shot. Here is the schematic from the article. I built the circuit on a small breadboard.