davedarkoSo I thought that my LiPo Chargers in form of 4056 modules are all weird, broken and not powerful enough, until I've noticed that my UNI-T UT61E multimeter isn't calibrated anymore(?)! Stupid me also calibrated other stuff like my Power Supply made from a buck down converter and a notebook PSU using that meter. I also thought my R8D8 power bank was off big time and the batteries were done, because I've continuously measured 3.8V on each cell with that multimeter... meh. Cheap multimeter now tells me I'm stupid. meh.
Anyone any tips for voltage references? Or how I can recalibrate voltage without another multimeter?
[update] I've seem to programmed all my attiny13 for #FLUX capacitor trinket with 13V instead of 12V, thanks to my multimeter... meh. but hey, they work.
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Do you happen to have at least TL431 somewhere in your junkbox?
They often appeared in ATX power supplies or other switching supplies, ready to be scavenged. Look for TO-92 package near optocoupler. It isn't great voltage reference, but cheap and plentiful - perhaps acceptable for interim use, while something more accurate is on the way.
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Probably still better that an LDO for 3.3V :)
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A diode voltage drop should be pretty consistent?
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I've checked eBay and youtube and came across an AD584 board that's a voltage reference for 2.5, 5, 7.5 and 10V - that should help. There was also a Max6143 5v reference that I was able to buy cheap. Much of hacking seems about the tools these days :D
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I have one of those AD584 ebay references. It was dead-nuts accurate according to my out-of-calibration HP 3478A - the readings matched the calibration voltages that had been written on the bottom of the case by the maker/seller. The whole board case and everything was cheaper than a new bare AD584 - I read somewhere that they're probably recycled parts. Anyway, it's become my primary reference.
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