Find 12VAC Dual Voltage Power Supply - Preamp Board

Thread Starter

TrinomiaI

Joined Mar 14, 2018
3
Hello all,

I need some help figuring out what kind of power supply to use with this preamplifier board. Screen Shot 2018-03-14 at 10.24.54 PM.png . Originally I had it working with a desktop DC power supply, +17V, GND, -17V at each of the power input screws. Now I want to test it out of the lab and need the appropriate AC wall adapter. I got and tested the board with this one from Triad Magnetics which is 24VAC. It does not work and the issue is believed to be a ground loop. The transformer I got is ground pass through and not center tapped.

Does anyone know where I can find a 24VAC center tapped plug in transformer with 3 screw terminals? On the other hand, is there a better solution? For such a simple little pre-made board, one would think that the ideal power supply is easy to come by.

Thanks in advance,
Alex
 

Thread Starter

TrinomiaI

Joined Mar 14, 2018
3
There's a good chance that it will also run from DC.
Do you have a schematic of the board?
No, only the picture that I attached. I know that it works with around + 17 and - 17 volts DC on a desktop supply, but figured I'd get what it asks for (AC) since I only have 9 VDC wall adapters on hand
 

dendad

Joined Feb 20, 2016
3,316
If you have a 12VAC plugpack, try it connected to one of the 12VAC pins and GND. It may work enough as half wave rectified.
Another thing you could try, opening the DC plugpack and disconnecting the inbuilt supply board and running the low volts AC out. But better would to get the proper transformer.
12VAC out plugpacks were used on a lot of old modems so they would be available at recycle stores.
 
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