switch mode supply

R. McAnally · 23rd December 2002, 03:19 PM

anyone mess around with the 12v => +-35v switchmode supply on the ESP site? justgot done building a prototype but seem to be having a little trouble with getting the windings just right. my first shot at it produced +70v and -35v and sucks way too much current at idle. i'll take another shot at winding the x-former tonight.

SkinnyBoy · 24th December 2002, 02:36 AM

I have been looking at that for ages.. haven't gotten around to doing anythuing with ut until now... I am not using it for high voltage, I want to modify a computer powersupply to run off 12volts, for this I will also need to use the feedback regulation... I think you are using your transformer windings wrong..... maybe..

jackinnj · 24th December 2002, 01:30 PM

I posted the schematic of a Sorensen high voltage/high power supply at www.tech-diy.com/sorensen.gif You get the general idea.

The SG3525 and SG3524 or LM3524 are nice chips to start out working with, at least when you are starting out and experimenting. In the US they are about $0.40 to $0.70. There are much better chips for audio however. I think I have recommended the LT1533, or mandatorily take a look at www.linear.com's application notes on the chip to examine the issues involved with switchers and noise.

Don't attempt to build a switcher with point to point wiring. If you have to, (i.e. if you can't fashion your own PCB's or are just like me and too cheap to send out to a proto-house) use the vectorboard with a groundplane.

R. McAnally · 24th December 2002, 03:01 PM

i was using the wrong core and screwed up on the windings. I decided to set my goals on a lower voltage for the pre-amp stage of my 12v project. i got this thing to produce exactly +-15v at 97% efficiency around 100ma per rail. i used two mosfets (instead of the four) since this design is rather low current. at idle (powering two led indicators) it pulls 40ma from the 12v line, and the mosfets remain cold with no heatsink for up to about an amp of output.

although this testing has been done on a proto-board, I have already layed out a board in electronics workbench for the final design. i'll post some pics when they are done.

next i will take another shot at at two higher power versions (after the boards are etched).

dkemppai · 24th December 2002, 04:03 PM

Quote:

Originally posted by R. McAnally
anyone mess around with the 12v => +-35v switchmode supply on the ESP site?

Hi, Do you have a link? I do a lot with SMPS and transformers, and would like to take a look!

-Dan

Circlotron · 25th December 2002, 10:21 AM

Quote:

Originally posted by dkemppai

Hi, Do you have a link? I do a lot with SMPS and transformers, and would like to take a look!

-Dan

So do I, so so do I.

jackinnj · 26th December 2002, 01:22 AM

designs are built around the SG3524 and SG3525 -- not the lowest noise chips on the block

23rd December 2002, 03:19 PM	#1
R. McAnally diyAudio Member Join Date: Jan 2002 Location: California	switch mode supply anyone mess around with the 12v => +-35v switchmode supply on the ESP site? justgot done building a prototype but seem to be having a little trouble with getting the windings just right. my first shot at it produced +70v and -35v and sucks way too much current at idle. i'll take another shot at winding the x-former tonight.

24th December 2002, 01:30 PM	#3
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	for higher voltages I posted the schematic of a Sorensen high voltage/high power supply at www.tech-diy.com/sorensen.gif You get the general idea. The SG3525 and SG3524 or LM3524 are nice chips to start out working with, at least when you are starting out and experimenting. In the US they are about $0.40 to $0.70. There are much better chips for audio however. I think I have recommended the LT1533, or mandatorily take a look at www.linear.com's application notes on the chip to examine the issues involved with switchers and noise. Don't attempt to build a switcher with point to point wiring. If you have to, (i.e. if you can't fashion your own PCB's or are just like me and too cheap to send out to a proto-house) use the vectorboard with a groundplane.

26th December 2002, 01:22 AM	#7
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	ESP is Elliot Sound designs are built around the SG3524 and SG3525 -- not the lowest noise chips on the block

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24th December 2002, 02:36 AM	#2
SkinnyBoy Banned Join Date: Nov 2002 Location: Adelaide, Australia	I have been looking at that for ages.. haven't gotten around to doing anythuing with ut until now... I am not using it for high voltage, I want to modify a computer powersupply to run off 12volts, for this I will also need to use the feedback regulation... I think you are using your transformer windings wrong..... maybe..

24th December 2002, 03:01 PM	#4
R. McAnally diyAudio Member Join Date: Jan 2002 Location: California	i was using the wrong core and screwed up on the windings. I decided to set my goals on a lower voltage for the pre-amp stage of my 12v project. i got this thing to produce exactly +-15v at 97% efficiency around 100ma per rail. i used two mosfets (instead of the four) since this design is rather low current. at idle (powering two led indicators) it pulls 40ma from the 12v line, and the mosfets remain cold with no heatsink for up to about an amp of output. although this testing has been done on a proto-board, I have already layed out a board in electronics workbench for the final design. i'll post some pics when they are done. next i will take another shot at at two higher power versions (after the boards are etched).

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