bobleny Posted August 18, 2010 Report Share Posted August 18, 2010 This should be fairly easy to do, I just don't know how to do so, I was hoping someone here could help me out.I built a full wave bridge rectifier using 4 diodes. I put 116V AC for my input, and I got 103.8V DC out. I'm trying to figure out what my output is when my input is, for example, 125V AC or 110V AC...I could just break out my variable transformer to some 220V and take a few measurements but, as it turns out, I don't have one. lol :'(The alternative, of course, is math! If I knew what the output was when the input is at 100V and 120V, I could probably figure out how to calculate the output at 110V. Unfortunately, or perhaps fortunately, my power company doesn't usually fluctuate that much. Well, that doesn't work so well. ::)In case you where curious:I have here a transformer with three outputs, 8V, 16V, and 24V. The input was fairly consistent 115.4V AC.This is the output: At the Transformer At the Rectifier Voltage Drop 25.7V 22.7V 3.0V 17.5V 15.4V 2.1V 08.3V 07.1V 1.2V My data suggests the their is a correlation between the input voltage and the voltage drop at the rectifier. If you're good at math, you should be able to determine the correlation and create a formula. I'm not one of those people, so carrying on...The voltage drop on a diode, as I recall, is .7V but, that doesn't explain the 12.2V drop that I am seeing. However, on the one side I am reading full AC, where as on the other chopped DC. I am assuming it is this choppiness (Ha, choppiness is a real word!) that is giving me the voltage loss. However, I currently have no way of testing this theory.If you have a formula for calculating this, please share!Does anyone have any other ideas?Thanks! Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 19, 2010 Report Share Posted August 19, 2010 When you rectify an AC voltage with a rectifier then you probably want DC. But the output of a rectifier without a filter capacitor is pulsing DC but an ordinary DC voltmeter reads the average voltage.A pretty high value filter capacitor will produce a smooth DC voltage that is 1.414 times higher than the transformer's AC voltage minus 2V if the rerctifier is a full-wave bridge and has its max allowed load current. The DC voltage will be higher if there is no load. Quote Link to comment Share on other sites More sharing options...
bobleny Posted August 24, 2010 Author Report Share Posted August 24, 2010 Thanks, that's easy enough! Quote Link to comment Share on other sites More sharing options...
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