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σ25 and σ26 power supplies as dual rail?

sigma25, sigma26, sigma24

σ25 and σ26 power supplies as dual rail?

Postby Unkgd » March 11th, 2018, 5:22 pm

Due to a combination of wanting a more efficient and cleaner power supply for my speakers ASP, I am considering building the σ25 and σ26 power supplies in a dual +5/-5VDC configuration. Draw will be about 500ma peak/ 300ma average. The σ25 and σ26 will be more cost effective and size appropriate than a σ22.

I intend to use the σ78 and σ79 for these power supplies, primarily as a SMD soldering test for myself.

Went through the threads on the σ25 and σ26 portion of the forum and only found one thread that briefly mentioned this option. From that thread it inferred that all that had to be done to configure the σ25 and σ26 supplies as dual rail is to tie the input grounds and the output grounds together.

But I also took a look at the σ22 schematic. and there are more connections to the common ground than just tying the input grounds and the output grounds together.

Just want to verify the proper method of configuring σ25 and σ26 power supplies as dual rail.

TIA,
Bill
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σ25 and σ26 power supplies as dual rail?

Postby amb » March 12th, 2018, 12:47 am

To set up the two boards as dual rail, use a transformer with two secondaries and wire one of them to the σ25 and the other one to the σ26. You could also use two separate transformers. There is no "input ground" to tie together. At the output side, connect the σ25 DC Out (-) output to the σ26 G output, and treat it as ground. The σ25 V+ is your positive output, and the σ26 V- is the negative output.

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Re: σ25 and σ26 power supplies as dual rail?

Postby Unkgd » March 12th, 2018, 3:54 pm

Thank you for the clarification.
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