Bridge rectifier power source

[imsellingmyfoot]

I am having problems with a bridge rectifier power source I built. I have traced the problem to the rectifier diode I am using. My voltage going into the diode is ~25 VAC. My voltage coming out as DC should be the same, one positive and one negative, correct? My multimeter is reading negative ~29 V DC and positive ~6 V DC. The diode was spec'ed as 8 amp and 400V tolerances. Is there a possibility that there is something wrong with my circuit (I don't think so), or is this just a diode that is messed up?

Thanks

 

[bob91343]

I think the problem is in your measurement. You measure 29 and 6 Volts with respect to what? A bridge rectifier has only two output wires and you measure between them.

 

[aardvarkash10]

(25 x 1.414) - rectifier losses = 35-ish (or, 29 + 6)

Well done Sherlock!

 

[imsellingmyfoot]

Measuring across from the positive lead to the negative lead gives me ~37 V.

My drawing says coming out of the diode should be +22V and -22V but I am using a different transformer, therefore my numbers are higher. Shouldn't my positive and negatives be equal though?

 

[DF96]

Is the centre-tap of the transformer grounded? Does it have a centre-tap? If not, you are in effect measuring via the leakage resistance of the transformer (or something).