I’ve blogged this project more than once in the past, (and here too), but I didn’t follow through with the circuit completed and installed in a DMM. Well, I finally got my act together and on the road, and finished the first working 1.5V to 9V DMM power supply. I thought about it and concluded
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I built this up to see how well the blue LEDs I got recently would work on the DC output of a JT. I put three pairs of two in series on a perf board and soldered them to the air wired JT. I knew that the Vf of two blue LEDs was going to
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I built this 1.5V to 9V DC-DC converter. It’s a modified Tim Williams design. It’s a Joule Thief with the output rectified and filtered, which is compared to the “Vref” zener diode and if the output voltage is too high, it turns off the base bias current to the Q2 driver transistor. The input is
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I commented on a Youtube video and the author replied he found that he could get PC Boards made for cheap from Futurlec.com. I looked at their FAQ and found that they will accept designs made in ExpressPCB, which is what I use. Their cost estimator said I can get the same boards for 44
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This is a continuation of the earlier blog. I wanted to change two parameters, the flash rate and the peak LED current. To do these, I experimented with the following. Flash Rate I built a sixth one (or seventh – I’m beginning to lose track, even though I labeled them). I changed the C1 capacitor
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I drew this schematic almost ten years ago, and of course the actual charger is nowhere to be found. I think it may have burned out somehow, and that was why I drew the schematic. Whatever the case, it does have current limiting, which has to be in anything like this that might be used
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I’ve thought about this a number of times in the recent past. There used to be a .ZIP file on the ‘netcalled Xanadu Zapper which consisted of plans and code to implement an IR xmit/recv interface for the PC along with code for learning and sending the IR codes. Many years ago I built the
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I had a thermocouple from an appliance lying around in the garage and I decided that it would be a good idea to experiment with it. It was a used one, but I don’t know what it was from; maybe a water heater. But a long time ago I had cut off the end that
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I finished gluing the 10 000 uF capacitors down to a piece of wood. I now have a Massively Parallel Capacitor Array (MPCA) Now the hard part comes: connecting all 150 of them up in parallel. I bought a whole box of 250 electrolytic capacitors on tape and fan folded. They were only ten dollars
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I watched LAaRT on PBS OC tonight and was introduced to this guy who custom crafts guitars. On the episode they showed him talking about a wafer switch that he said came from a telephone system. This switch is like a rotary switch turned on edge and a lever added to move the contacts to
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