I have a number of old audio amps that I want to gut and use the PSU's to build Chipamps (gainclones, etc).
The problem is many of the old amp PSU's are higher than +/-50VDC and many chipamps can only handle +/-40 to 45VDC.
I also need 5+ amps.
Anyone have any simple circuits I could adapt, like with 3055's etc?
Thanks for any help,
-Rich-
The problem is many of the old amp PSU's are higher than +/-50VDC and many chipamps can only handle +/-40 to 45VDC.
I also need 5+ amps.
Anyone have any simple circuits I could adapt, like with 3055's etc?
Thanks for any help,
-Rich-
Run the original power supply from a step down transformer or variac?
VPT100-5000
https://www.amazon.ca/YaeCCC-Transformer-Variable-Voltage-Controller/dp/B07L2Y9WVP
VPT100-5000
https://www.amazon.ca/YaeCCC-Transformer-Variable-Voltage-Controller/dp/B07L2Y9WVP
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The problem I see is the supply has a +50V and -50V output, but you cannot use the negative rail, because the ground levels are different and the power supply or fuse will blow up when connecting them together.
IMHO it would be better to throw out the big transformer and caps (which anyway should be renewed) and get a small switched supply with the proper U and I rating for your modules.
IMHO it would be better to throw out the big transformer and caps (which anyway should be renewed) and get a small switched supply with the proper U and I rating for your modules.
Not sure what you mean.
A bucking transformer acts on the primary side and lowers *all* secondary voltages by the same percentage.
secondary wiring does not change, center tap goes to ground as usual, etc.
That said, *personally* I´d use supplies as-is and build discrete or use Sanken modules if chipamps are preferred.
Gainclones and such mean LM3886 or perhaps TDA729* , a completely different class from the 500W beasts you have.
If you insist on smallish chipamps straight get the proper power supply.
A bucking transformer acts on the primary side and lowers *all* secondary voltages by the same percentage.
secondary wiring does not change, center tap goes to ground as usual, etc.
That said, *personally* I´d use supplies as-is and build discrete or use Sanken modules if chipamps are preferred.
Gainclones and such mean LM3886 or perhaps TDA729* , a completely different class from the 500W beasts you have.
If you insist on smallish chipamps straight get the proper power supply.
Thank you for the replies, folks!
I carefully read each.
On the one hand, it's hard to justify spending a lot for more items or building a circuit that costs almost as much as the correct transformer.
On the other, its so hard to throw out pro gear PSU's with massive transformers just because the DC is 5-10+ volts too high for chipamps.
I mean I have Hafler, QSC, Crown, Crest, etc. Circuits are blown, but PSU's are still good, but they are +/- 50 to 70VDC raw.
My only other thought (besides your suggestions) was to try and uncoil some of the windings, or use diodes to drop (if I only needed 5 volts or so).
It's also possible some have taps for 220VAC input I could use and that with 110VAC and it should drop the secondary to half.
I was hoping for something like this, but lower voltage, added transistors for current, and a mirror design for the - supply:
DC Power Supply design
Anyway, thanks for any other suggestions.
-REW-
I carefully read each.
On the one hand, it's hard to justify spending a lot for more items or building a circuit that costs almost as much as the correct transformer.
On the other, its so hard to throw out pro gear PSU's with massive transformers just because the DC is 5-10+ volts too high for chipamps.
I mean I have Hafler, QSC, Crown, Crest, etc. Circuits are blown, but PSU's are still good, but they are +/- 50 to 70VDC raw.
My only other thought (besides your suggestions) was to try and uncoil some of the windings, or use diodes to drop (if I only needed 5 volts or so).
It's also possible some have taps for 220VAC input I could use and that with 110VAC and it should drop the secondary to half.
I was hoping for something like this, but lower voltage, added transistors for current, and a mirror design for the - supply:
DC Power Supply design
Anyway, thanks for any other suggestions.
-REW-
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