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Simple and compact +5/+12/-12 PSU for SEQv4


Altitude
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This is based on a previous design I had used in the past with some improvements (smaller size, switching 5V reg).  Its a 7VA trafo which gives 580 mA max, not a lot but enough for my needs (size was the big factor here).  Standard 7812 and 7912 linear vRegs with a switching Recom R-785.0-0.5 for the +5. Total cost was ~$50 including the board.  If anyone is interested, I'll post the BOM and eagle files

 

PSU5+12-12.jpg

 

PSU5+12-12brd.png

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Lookin´ very nice, man! :-)

Especially the linear regs are good for AOUT stuff - methinks using switchers (like in those commonly available "open frame psus") are not top notch for feeding into modular stuff...

 

Many greets,

Peter

Edited by Hawkeye
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Lookin´ very nice, man! :-)

Especially the linear regs are good for AOUT stuff - methinks using switchers (like in those commonly available "open frame psus") are not top notch for feeding into modular stuff...

 

Many greets,

Peter

If you want to use a linear regulator for modular stuff, wouldn't you rather use an LM317/337?

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I didnt go with the adjustable for simply for size, no need for it here.  I may need to make some 220V versions of this and would be willing to offer 2 boards with the right transformer, switching 5V vReg, and bridge rectifier as a partial kit.  If anyone is interested, shoot me a PM

Edited by Altitude
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  • 3 weeks later...

Also there may be a problem with this transformer.

The min input voltage fora 7812 or 7912 is usually a few volts more than 12v.

Voltage regulators like the 7812 usually call for 14v min input.

So i would imagine that the transformer should be slightly larger 14v or even 18v per side.

I'm using a 36v center tapped transformer for my modular and it works nicely.

Have you tested this supply with a load?

Edited by k-rAd MB6401
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yes. works fine. (12VAC x 1.414)-1.4 = 15.4 VDC.

Using a 18-0-18 trafo for a +/- 12 setup is a waste and you're just burning off that extra voltage as heat. Measure the input of your vRegs, you are probably around 24V!

A transformers VAC output is an RMS measurement so to find out the corresponding DC output (at load) the formula is VP =(V secondary rms x 1.414) - 1.4 V

Edited by Altitude
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