Scalable PSU/regulator GB

[BobEllis]

Sure, ideally the Ns to the Ps below them would be perfectly complimentary, but physics generally makes them less than perfect compliments. It would be interesting to see the reference and how to match them. I didn't match mine.

[cfbuck]

You were correct Bob.

I attempted to find the reference and it is in the Leach notes. But the transistors to be matched are the T1, T2 etc. So I was confused. At my age one should never write from memory late at nighwithout checking the references.

I never matched those either but I will see how it goes before pulling any.

[cfbuck]

Bob, I forgot to attach my 3rd attempt at the circuit to a previous post. I hope that I have it now.

[BobEllis]

That's it.

[cfbuck]

It's been a while but I would like to report back, Bob.

I have just hooked up the voltage doubler and the PSU. When first powered up the output of the +ve channel was 64.2 and the -ve one 68.3. Adjusting the pot on the -ve channel brought it down to 64.2 also. they are now matched. So that is the voltage that will go to the VC and VS connections on the Leach pcb.

I have made rather amateurish capacitor banks for the amp which will accomodate 5 10K 80V caps each. If I am understanding this correctly, both the voltage doubler and diode bridge which feeds the smoothing caps will connect to the transformer. The cap banks will connect at the VCC and VSS. No resistors will be inserted at R2 and R21. The voltage at VCC and VSS should be around 40*1.4 or 56. Is my interpretation correct?

Any further questions I will submit to the Leach thread.

Thanks so much for your help Bob.

[cfbuck]

Got the resistors wrong in the last post. They should be R1 and R23.

[BobEllis]

You've got it right. Did you size R3 and R22 for 65V operation?

You'll probably have closer to 55V for VCC and VSS due to the diode drop in the bridge.

Be sure to verify reliable starting of the front end regulators before connecting speakers.

[AndrewT]

I get ~+-58.5Vdc from a 230:40+40Vac transformer when fed from a 240Vac mains supply. And it varies from hour to hour.

[cfbuck]

LOL. It'll be a while before the Leach gets to the speakers. But it is a lot closer than it was 3 weeks ago-a blank board.

Thankyou both. I appreciate your help and patience with me. BTW, Andrew, the B1 powered up just fine, thanks to your help. I haven`t yet hooked it up for a performance. I have a lightspeed clone (dvb-projekt) to go with the B1 for volume control. Hopefully they will combine with the Leach just fine.

Bob, the resistors for R3 and RR22 are 3.9K 1W. The protection circuit .5W values that I have are:

R41-43, 60-62 1.2K
R28,30 270
R26,30 4.3K

Emitters .47R 5W

[cfbuck]

Also R68,69 33K