Gainclone power supply

soundNERD · 1st February 2004, 10:07 PM

Hi,

I need to power 2 lm3886 chips (in either stereo or mono mode) from a 12V 20A supply (a car)

How would I go about turning the 12V into +-20VDC at about 10A? Is this possble and simple?

Thanks!

-Mike

crown300 · 1st February 2004, 10:45 PM

The clasical answer would be that you need a switching power supply, 12 Volts in, +/- 20 out.
for example: www.national.com if you want to build such a supply.

http://www.national.com/appinfo/power/
(center page = design)
using 12 to 14 input, 20 volts @ 2 amps out suggests using a
LM2587-adj chip for the +20.

If I was doing it for an Industrial solution I would use a vicor supply (www.vicr.com) - but not cheap.

the 10 Amp part is not as easy though.

soundNERD · 1st February 2004, 11:12 PM

Thanks, I'll check that out.

What is the max amperage I could get out of that?

Even 5A would be enough.

-Mike

theChris · 2nd February 2004, 04:16 AM

i'd get all the home amps done first really. that's my plan, finish my home amp tomorrow and then later move on to other projects. like how small can a 100 watt amp be made? my goal is a HDD sized block, more for novelty though.

theChris · 2nd February 2004, 06:55 AM

actually, i may have had you confused with someone else. to get +-20V you will need a SMPS. if you feel confident in your abilities, then go for it. if you don't, then do more research.

Lovan · 2nd February 2004, 11:07 PM

Quote:

Originally posted by soundNERD
Thanks, I'll check that out.

What is the max amperage I could get out of that?

Even 5A would be enough.

-Mike

Max 5A

http://www.national.com/pf/LM/LM2587.html

soundNERD · 3rd February 2004, 01:37 AM

now, how to get the - rail?

theChris · 3rd February 2004, 03:03 AM

my guess would be to use a center tap. or use ac coupling.

soundNERD · 3rd February 2004, 11:23 AM

How do I centertap a chip?

theChris · 3rd February 2004, 01:34 PM

i think he's gonna need real FETs for this. the flyback or forward topology may be ok, but he is asking for 400VA, not that they can't be built for such.

in anycase, the center taps would be on the transformer, with an example being on page 1 of the datasheet. it looks like thre is 5A into the IC which means less then 5A on the transformer output.

in anycase the 2 designs are similar -- both pulse the transformer. the forward converter is lower noise but needs an extra primary and extra diode.

1st February 2004, 10:07 PM	#1
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	Gainclone power supply Hi, I need to power 2 lm3886 chips (in either stereo or mono mode) from a 12V 20A supply (a car) How would I go about turning the 12V into +-20VDC at about 10A? Is this possble and simple? Thanks! -Mike

2nd February 2004, 04:16 AM	#4
theChris diyAudio Member Join Date: Dec 2001 Location: SIUE, Illinois, USA	i'd get all the home amps done first really. that's my plan, finish my home amp tomorrow and then later move on to other projects. like how small can a 100 watt amp be made? my goal is a HDD sized block, more for novelty though. __________________ if only it could be used for good, not evil...

2nd February 2004, 06:55 AM	#5
theChris diyAudio Member Join Date: Dec 2001 Location: SIUE, Illinois, USA	actually, i may have had you confused with someone else. to get +-20V you will need a SMPS. if you feel confident in your abilities, then go for it. if you don't, then do more research. __________________ if only it could be used for good, not evil...

3rd February 2004, 03:03 AM	#8
theChris diyAudio Member Join Date: Dec 2001 Location: SIUE, Illinois, USA	my guess would be to use a center tap. or use ac coupling. __________________ if only it could be used for good, not evil...

3rd February 2004, 01:34 PM	#10
theChris diyAudio Member Join Date: Dec 2001 Location: SIUE, Illinois, USA	i think he's gonna need real FETs for this. the flyback or forward topology may be ok, but he is asking for 400VA, not that they can't be built for such. in anycase, the center taps would be on the transformer, with an example being on page 1 of the datasheet. it looks like thre is 5A into the IC which means less then 5A on the transformer output. in anycase the 2 designs are similar -- both pulse the transformer. the forward converter is lower noise but needs an extra primary and extra diode. __________________ if only it could be used for good, not evil...


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1st February 2004, 10:45 PM	#2
crown300 diyAudio Member Join Date: Oct 2002 Location: pittsboro, NC	The clasical answer would be that you need a switching power supply, 12 Volts in, +/- 20 out. for example: www.national.com if you want to build such a supply. http://www.national.com/appinfo/power/ (center page = design) using 12 to 14 input, 20 volts @ 2 amps out suggests using a LM2587-adj chip for the +20. If I was doing it for an Industrial solution I would use a vicor supply (www.vicr.com) - but not cheap. the 10 Amp part is not as easy though.

1st February 2004, 11:12 PM	#3
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	Thanks, I'll check that out. What is the max amperage I could get out of that? Even 5A would be enough. -Mike

3rd February 2004, 01:37 AM	#7
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	now, how to get the - rail?

3rd February 2004, 11:23 AM	#9
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	How do I centertap a chip?

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