# 12 0 12 Transformer to get 12V and 24V simultaneously.

#### virtualbjorn

Joined Jan 10, 2019
6
Hi! I'm designing a power supply that can output 12v and 24v simultaneously at the same time using a 12 0 12 CT Transformer. Is there any good circuit for it?

#### ericgibbs

Joined Jan 29, 2010
11,637
Hi v,
Welcome to AAC
Yes its possible to get 12V and 24V, supplies from that transformer, what current and level of voltage regulation do you have in mind.?
E

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#### crutschow

Joined Mar 14, 2008
26,053
The circuit below should do what you want.
Note that for proper derating, the sum of the DC currents from both outputs should be no greater that about 50% of the transformer VA rating.

#### virtualbjorn

Joined Jan 10, 2019
6
The circuit below should do what you want.
Note that for proper derating, the sum of the DC currents from both outputs should be no greater that about 50% of the transformer VA rating.

View attachment 167500
Hi! The RLoad2 is still on DC, right? Forgive me. I'm not too familiar with how center taps work.

Can I also use 1N4007 instead of 1N5819?

#### crutschow

Joined Mar 14, 2008
26,053
The RLoad2 is still on DC, right?
Yes.
Look at the output (red trace).
Can I also use 1N4007 instead of 1N5819?
Yes, if you can tolerate about an extra volt drop in the V+ output and an extra half volt drop in the 1/2V+ output (below).

#### AlbertHall

Joined Jun 4, 2014
10,783
Note that with a rectifier circuit only and a 12V transformer you will get more than 12V/24V output - something like 14V/28V. You could use regulators to back to 12V/24V and make the voltage more stable.

#### virtualbjorn

Joined Jan 10, 2019
6
Thanks everyone for giving me answers. Appreciate it.

#### virtualbjorn

Joined Jan 10, 2019
6
I made the circuit and I've tried the schottky as well as the rectifier diode and I got a whooping 34-35V from the 24V line which what I aiming to get. And about 15-17V on the 12V line.
The rectifier diode gives me less than my desired output voltage so I sticked to using 1N4007 diodes for the application.

#### crutschow

Joined Mar 14, 2008
26,053
The rectifier diode gives me less than my desired output voltage so I sticked to using 1N4007 diodes for the application.
What are the rectifier diodes?
What Schottky diodes?
The 1N4007 are regular diodes, not Schottky.

#### virtualbjorn

Joined Jan 10, 2019
6
What are the rectifier diodes?
What Schottky diodes?
The 1N4007 are regular diodes, not Schottky.
I bought a 1N5819 Schottky Diode to compare it with a 1N4007 Diodes

#### crutschow

Joined Mar 14, 2008
26,053
I bought a 1N5819 Schottky Diode to compare it with a 1N4007 Diodes
So the 1n5819 is your "rectifier diode"?
It's output voltage should be higher than the 1N4007.