u/Maleficent-Tea2903

Hi All

Once again, I need a schematic review for sanity checking this supply. On the same PCB (though, electrically isolated if needed, see the jumpers on the top-sheet), I have three power supplies for an experimental setup we are making. One is a ±6V supply (directly from the manufacturer's eval board) for the Cremat Preamplifiers we are using, which I know works electrically. The second is a low voltage variable supply, from 0-24V (range is roughly, but should be precise to at least 0.1V). The third is a 0 to -4000V supply, precise to at least a volt.

The two variable supplies are used as biasing lines for the preamplifers (through AC Decoupling), and we are looking at, in theory, quite small signals, think hundreds of femtocolumbs, or 100mV signals on the highest gain amplifier. As such, both of these biases need to be extremely stable. This is the motivation for the design here, on both lines, as well as overall, and why you may notice a large number of components on the LV supply. Specifically, our expected rise times will be on the order of 10ns, so noise from 1/2 to 2x this value is what we specifically aim to remove, however, we still do not want kHz/GHz noise either...

Moreover, since I will be leaving the lab I'm working in, this is designed to be extremely serviceable, and as such is designed completely analog, and with only THT components where able.

I have a few specific questions:

1.) For the ±6V supply, do the components I have selected, assuming TO-220 THT packages, meet the thermal requirements for a 600mA overall load? My main concerns are, of course, the LM-317, which drops 24V to 16V, and the transistors. The transistors, unfortunately, look to be obsolete and are not THT, so I will need to choose something else of similar spec, but currently are (MMBT3904 and MMBT3906), which should be pushing the current. If needed, if these are TO-220's, I can attach heatsinks. I'm 99% sure they do, but a simple sanity check would be nice. Moreover, I also would appreciate THT suggestions for the transistors, if able.

2.) For the LV Supply, you may note that the voltage and current monitoring are on the output line... will this cause significant noise on my line? If so, is there anything I can do to mitigate this? Do I need to put the monitors somewhere else in the line, and if so, where?

3.) Furthermore, if able, for the LV Supply are there any THT replacements you can recommend for the OPA197? Not urgent, I can figure this one out myself if needed.

4.) For the HV Supply, which utilizes the HRC0524S4K0N as it's DC-HVDC converter, will the current filtering isolate the ripple noise? In theory, the HRC05 should keep it already down below 0.01%... In practice, though? The devices in aggregate should have, at most, a peak draw of no more than 50uA, for reference. If there is a issue, could you help me find a solution?

5.) Furthermore, assuming correct PCB design (which I know how to do), is this schematic safe to use? Are there physical safety concerns from the electrical connections, assuming an idealized implementation?

6.) Last, but certainly not least, are there any dumb errors you can see? Is something clearly not connected, or is there something I'll blow up if I plug this in?

Please let me know if you have any questions on components or specific requirements, etc, and I'll be happy to reply asap to the best of my ability. Thank you so much in advance!