[Budgie]

I am buiding another Skeres and have run into an issue with the lm317 regulators I use for the constant current source. In my first amp, the ccs worked out to exactly the current expected, and the two ccs's matched each other very tightly. On the new amp, the ccs's are way off. Should be about 125 ma each with a 10 ohm resistor, and I end up with 57 ma on one, and 98.5 on the other one! The power supply is +/- 15vdc, and my resistors both read exactly 10.5 ohms on my dmm. I can't find any problems with wiring etc, and the power supply is not sagging under load. This is happening with the ccs's out of circuit comletely. I am suspecting I have a couple of screwy lm317's, but I wonder if anyone else has any idea's?

 

[L Daniel Rosa]

Did you connect the Vout pin as the cathode or the common pin? If you used the Vout pin, that'll give screwy results.

 

[Budgie]

Looks like thats what I did, allright. Silly me. Thanks Dan!