An arguably better replacement for the resistor in a CRC power supply - R21 PS module

Thanks for the answers. The F3 PSU is already built a few years back. Because of Covid pandemic (and being a physician) I went completely away from DIYAudio and recently came back a few weeks ago to find many new interesting projects. I am sure I will find a way to fit it into the already built PSU, probably with some hex spacers or so. So I will built two positive regulators, use TTA004 and TTC004 due to the other Toshibas being obsolete and my stack is replenished.

Thank you for this great design @tombo56
 
Some progress. On the bench under light load massage and measurements. 😀
Test with 22 A peak load. Blue trace is voltage over 0.165 Ω inside active load and yellow is regulator output.

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Ah, that's right. Here are the values I ended up using: (Same values for each channel.)

CS1 (100nf), CS2 (10nf), and RS1 (20R) are typical snubber values via quasimodo.

The bridge rectifiers are IXYS VBE60-06A.

For the big capacitors, I consulted Tombo and ended up using 22,000uf/63v for C1 (based on anticipated ripple of my B+, 48v) and a 10,000uf/80v Kemet cap for C2.

Finally, the bleeder (Rbl) is 2.2k and the thermistors are CL60.
 
No they are not. I bought a few of them a while back and now I try and use them whenever I can. That said, I did include a couple spots where one can use an offboard rectifier and bring the DC back in directly. The '+' and '-" connections next to the TO-227 connections. GIves me an option to swap in some LT4320 rectifiers if I need an extra 1.5v.
 
@tombo56 , any concern with 72c temps for SUP70101? That’s measured on the device body, as well as directly behind on heat sink. Load is 2A and about 2v drop across R21-P. The datasheet suggests a max of 175c junction temp, so running at around 40% of max.

The regs are running great, it’s just a matter of the amp output devices dissipating a lot of heat and driving up ambient temp of chassis. Good, old fashioned SE class A amp 🙂
 
@codyt, a question on your dual mono PSU where you have used 2 off positive R21 add on regulator boards. Did you connect the G terminals on the pos output (upper reg) to the V+ terminals on the lower supply ( which is the GND on the PSU) to get the minus VDC from the G terminals on the lower reg? I also assume then TH4 is not used.

Hope that question is clear, just making sure I have the connections correct for a +/-VDC dual supply.

Or maybe your pcb is only for 2 off pos supplies.
 
I’m using it to obtain two separate positive rails, as the amp I’ve been working on only requires the single rail per channel. I hadn’t considered making a bipolar supply with these boards, but I can take another look and see how difficult it would be. Taking two pos R21 to make a bipolar supply is something Tombo would need to comment on.
 
any concern with 72c temps for SUP70101?
No concerns at all. This is mild operating temperature. 🙂
All electrolytic capacitors are at max. available distance from the heatsink, so I consider heatsink temp. up to 85-90° C as normal operating conditions.

However, 2V drop is unnecessary. R21 modules operate at full performance even with 0.3V drop. Considering ripple at first capacitor, minimum should be 0.7V. Check voltages when mains voltage is at usual minimum (early morning and evening in my area i.e.) and readjust to have 0.7 – 1V at such conditions.
 
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