The hundred plus dollar DMM (digital multimeter) I use on the bench has an auto shutoff when it’s not being used, but the cheapo Cen-Tech DMMs from Harbor Freight do not, so if we forget to turn it off (and even the best of us do), then the “Extra Heavy” 9V battery that comes with
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I bought a PATA/SATA to USB adapter that consists of the adapter, an AC power brick and assorted cables, including the power cord from the power brick to the wall outlet. This world standard power cord is just like the ones on PCs, monitors, printers, etc., but it’s short, about a meter long, But the
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I bought a Joule Thief at the store today. Well actually there’s more to it than just that. Yesterday I stopped by Harbor Freight and bought a heat gun (that’s another story) and I saw something that caught my interest. It was a battery tester for $2.50 that had three LEDs. It tested two kinds
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A few years ago I made a LED tester that used a 9V wall wart, a 5V zener for a shunt regulator, and three 100 ohm resistors to limit the LED current – one resistor for each LED socket. The problem with this was that it was plugged in all the time and since it
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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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Cyrodyl posted a schematic file named FET Dip Meter.PNG (you may have to be logged on and joined to the group to view this), and this is my comment about it. I posted this comment file to the Yahoo group RegenRX2, which is the overflow from the RegenRX group, which deals with regenerative receivers. Comments
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Peter emailed me with a question about Geiger Counters. With his permission, I’ll quote his questions in the paragraph below and answer them following. it´s Peter again – a few weeks ago I purchased a good, sensitive (and fully functional!!) Geigertube for measuring background radiation – the only problem is that it requires 1000 Volts.
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Quantsuff says he’s getting one of these DC to DC buck converters combined with a meter, from a vendor on eBay named Kuuco (this link may go dead after a time, so do a search for “4.5-24V to 1-20V 2A Voltage Regulator DC Buck Converter Voltmeter Ammeter Blue”. What I think is a stinking shame
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This power supply circuit uses a LM317 or 7805 regulator chip to do the work. The problem is that when the wiper arm of R1 is turned to the position closest to the top, it will short the output to the common or adjust pin. This will cause the R1 pot to overheat and burn
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A long time ago I wanted to get a digital panel meter that is small, uses very little power (LCD display), and does not require a power source that is floating, in other words it can be powered from the same power supply that it’s measuring. When it’s measuring current, this is important, since both
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