Hi,
interesting. Do you have a diagram of this one ?
I have built some HV PSUs as well, look here:
https://electronicprojectsforfun.wordpress.com/power-supplies/high-voltage-lab-power-supplies/
Sure. It is your 250 V / 150 mA one. (Thanks for the diagram, hope that's Ok with you.) Although it wasn't too easy to comprehend the lo-res PNG.
I substituted the 2 references (voltage/current) with LM285-2.5, as I had only one TL431 with leads. The pass transistor is a 2SK1773.
I'm undecided whether I should search for a stronger transformer and what to do about heater voltage. I might also add 2 digital panel meters, as I have quite a few of them (Panaplex might be fitting).
But I dread the mechanics. Cases are expensive, and after I've finished my 'machining' they tend to look just horrible.
Cool ! Of course I have nothing against reproduction of my projects for noncommercial use. Just play safe, then everything is fine.
There's absolutely no danger of anything remotely commercial. Thanks again for the design.
For heaters there are two solutions:
- separate transformer (the tube audio guys gave those)
- combined anode/heater transformer (also available from tube audio shops).
The transformer I use right now has two heater windings, but since the mains voltage was raised to 230 volts, they're a tad too high (7.1 volts) for my taste. And I prefer DC, of course. Alas, 7 volts AC doesn't leave enough headroom for regulation to 6.3 volts after full-wave rectification.
A third transformer just for that? These are the reasons for my undecidedness.
And I have plenty of lab supplies (remember the 9 HP E6114A).
You can also choose from AC heating (possibly introducing hum into your circuit) or a DC heater power supply (I built some of those too).
As a first "project", I just want to get some light out of my Magic Eyes. Hum would definitely not be a problem there. But I love regulated supplies, and DC is so much easier in that regard.
Mechanics is almost never loved by electronics people. Its the same with me. One day I got tired of completely improvised constructions and I bought myself a computer controlled mill (CNC Step Hi-Z400T). I then made some tools to handle the Hammond cases and fix them inside the mill. For a more complicated case with a lot of round and rectangular holes (e.g. for panel meter), fan grills, ... this saves a *lot* of manual work. And it is repeatable if needed. So thats the explanation why a lot of my stuff looks so similar.
Another mechanical thing that I found useful is 3D printers. The blue part for the fan grill is such a thing. After some sobering experiences with Stratasys I now found a reasonable 3D printer that works much more reliably (Ultimaker 3). It starts making fun, the last part I made was a plug adapter for the Keysight autoprobe scope connector, like here (at the bottom):
https://electronicprojectsforfun.wordpress.com/using-the-keysight-autoprobe-interface-in-your-own-projects/
Gasp! Of course I keep dreaming about a mill, but that price is not easily justified. For this amount I could get quite a few milled plates from Schaeffer ... And where would I put it?
A last tip would be the MOSFET pass transistor. In my parts, I am now replacing the 2SKxxx and IRFxxx types by linear MOSFETS from IXYS. The are a bit costly, but they have a SOAR that guarantees that they wont blow up in linear operation. A shorted MOSFET could send your attached circuit to hell immediately, because the full input voltage will be released to it.
Yup, the 2SK1773 is intended for SMPS operations. But I see no risk of leaving the DC SOA here. Just for fun, I might try out a few BJT as well (so I actually use some of my components).
Have fun !
Wolfgang
At least I'm trying!
BTW: The main reason for posting that PSU construction was because I used one of those berated breadboards; "worked first time" was in reference to
that.