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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Archive for the ‘Electronics’ Category:
2013-03-05 1.5V to 9V DC-DC Converter For DMM
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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2013-02-23 PC Boards Cheaper
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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2013-02-17 Flashers Bowden Style (Continued)
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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2013-02-15 Cell Phone Charger, Auto Type
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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2013-01-30 IR Remote Emulator Learns and Sends
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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2013-01-05 Thermocouple Measurements
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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2012-12-23 Watson’s Massively Parallel Capacitor Array
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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2012-12-11 Dantzig Guitars
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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2012-09-14 9V Battery Substitute
DMMs All Over The Place – I have more than a half dozen of those cheapo Cen-Tech DMMs from Harbor Freight laying around my house, and I use them a lot for checking the AA and AAA cells that I’m constantly trying to drain with my germanium Joule Thiefs with their multicolored LEDs, of which
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