Wall wart power supply - 15V instead of 12V?

oscillate_wildly · Joined: Aug 12, 2008 Posts: 9 Location: London

I just finished putting together a strip board version of the MFOS Wall Wart power supply.

I'm using the L7812 and L7912. Both are heat sinked.

I am also using a 12VAC 1000mA wall wart.

When measuring the voltage, I'm getting the readings:

15.86V and -15.86V

I was hoping to get the readings 12V and -12V, as I am using it to power a Soundlab plus and the 1V/oct keyboard.

Does anyone know how I can reduce the voltage to the desired 12V and -12V?

(I'm putting the black lead of the multimeter on the negative terminal and the red lead on the positive terminal)

Thanks.

RF · Posted: Fri Feb 26, 2010 6:07 pm Post subject:

Can you post a pic of your circuit? Sounds like you may have something wired wrong...or those regulators are 7815 and 7915's

bruce

oscillate_wildly · Joined: Aug 12, 2008 Posts: 9 Location: London

Thanks for the reply!

I double checked the regulators, they are definitely 7812 and 7912.

On double checking, I think i may need to switch the regulators with each other.

oscillate_wildly · Joined: Aug 12, 2008 Posts: 9 Location: London

Switched them around, and now I'm getting 11.8V and -12V.

Problem solved!

RF · Posted: Fri Feb 26, 2010 7:12 pm Post subject:

Glad to hear it!

bruce