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@Jonny69
I made a start on the PSU:
Some thick angle which was an offcut from a work project. When I loaded up the LM350 with 2A, it got extremely hot. Loaded with 1A though it kicked out hardly any heat at all, so I decided to double them up. I put two in parallel, but they actually ended up fighting each other and one of them ended up doing all the work. So I thought a better idea would be to use both the 3A secondaries on the transformer, rectify both separately and run separate regulated supplies to each channel. I should be able to match the voltages to within 0.1V or better and it’ll save driving anything flat out or resorting to balancing resistors or using op amp voltage tracking. I’m aiming for strictly analogue and through-hole, no ICs!
That then brings us up to date. This is the 2x 27V 3A power supply built. Tracks reinforced with thick solder runs to handle the current. It actually goes up to about 55V and I could run it up at about 40V for a bit more output, but I’ve got it wound right down as per the OEM design. Got each channel within about 0.05V of each other which should be good enough:
I’ve mounted up the output transistors and added some wires to wire them in:
Note I used a paint pen to mark B, C & E on the heatsinks to make sure I got the wires in the right place. That’s this part of the circuit and the rest will be on the PCBs:
I’m not 100% happy with that, specifically the layout, because it’s a mess of wires carrying signals and power, all crossing over each other and poking through holes and it won’t surprise me if it picks up some noise. I’ll just have to wait and see what it does and if it’s a problem I’ll reconfigure it.
The side you can see looks much better:
There will be a cover over that because the transistor cases are live.