Oh and I’ve just used a green led for D6 (r3 position)
I’ve no idea - we need an expert. I’m just a follower.
It’s key where you cut the track from OP1. It needs to be between OP1 and C3+ rather than between C3+ and Opamp pin 7
Currently struggling with soldering together 7 x smd green leds for the voltage ref
Tim, did you already complete your 55V build?
OK, I put together a schematic, inspired from here, for a 40V version as a drop in replacement for the regulator board in Naim style power amps to power the front end (when running the power stage from a raw PSU):
John, many thanks, great instructions! I upgraded the schematic with your suggestions:
Can I also use the E-152 instead of the J506? I want to use the board for a NAP clone (and might try it on an original Naim too), so for the negative rail I also would need some regulating...
All good apart from the cap multiplier around Q2
FWIW I have a negative super-reg on my HackerNAP of the same design.
The reference can be altered to improve its rejection with the addition of a single transistor and resistor but perhaps that is for later
Hi jpk, what cap are you using for C9?
Also would it be possible to make space for 7 leds for those wanting higher voltages
Sorry to have dangled the carrot and then so cruelly ripped it away!
Check out the Wima MKS2 10uF 50v. They have a 5mm pin spacing on a 10mm X 7mm footprint.
BTW you mentioned a NAP500 style bridged configuration with a second couple of amp boards (see here and here): I would be very interested to try this as I owned a 500 some 15 years ago and found it vastly superior to even 6x135s active into NBLs at that time - a long gone great system, sadly, but hey, my life changed for the better
Just a comment - I think it's always better to get the rectifiers as close as possible to the transformer so it might be better to swap their position around. I appreciate that you’ve probably laid it out this way to get the output stage rectifiers on the heatsink but I’ve never found any issues with having them in free air and I’m using a 500vA 35v traffoThanks for helping, I edited the schematic in above posting and hope I got it right. Please alarm if there are still mistakes!
OK, I will make the negative version as soon as I have it all right. Already started with some basic layout (the TO220s are the rectifier diodes). The big PCB can be broken into individual circuits (hence so many mounting holes):