How about a GroupDIY bench power supply?

I have an idea!

I've been thinking about building a good bench supply for some time. Here is my wish list:

+/-12vdc to +/-24vdc variable
+100vdc
+250vdc

This would allow you to test both solid state and tube circuit ideas. I don't think this wouldn't be too hard to do with commonly available parts.

I'm thinking a variable regulator for the 12-24vdc side.

Any thoughts? Should I draw up a schematic and try to track down some parts them present it to everyone?

Actually, a +48vdc option for testing phantom power would be a good idea as well.

That could be done quite easily with a pair of LM3X7 and a trannie with dual high voltage secondaries..

I would include a beefy 6V/10A heater supply also and maybe a 40-100V/10mA bias supply that in a pinch could be used for phantompower testing.

As much as I dig PSUs :grin: , I've never bothered making a variable HV supply. If I was located in the US I'd buy one of those nifty surpluss Lambdas. They don't cost much but would be a nightmare to ship to Europe.

I'm still happy with a Variac and some caps. I've used that for +10 years now. I have several other low voltage bench supplies though..

I have something like this that works well for most applications....

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=58287&item=3823232131&rd=1

is heath kit even in business anymore?

Well, I'm just thinking about how I could make an all-in-one bench supply that would hopefully not cost too much dough. I really need one before I can do much more with this hobby.

A friend of mine uses an old AT computer power supply for playing around. It does +5v and +12v, but is pretty well-regulated. They can also be had for dirt-cheap or free. He doesn't do much audio stuff, though, so he doesn't miss not have +/- supplies around.

Scen,

That looks pretty nice and useful. actually. Thanks for the link.

I think a 0-80V/500mA option would be nice too... See, this is where it get's difficult to make such a project. We probably all have different needs. It would also require a custom trannie or a bunch of small ones. Meters and what not. Gets expensive. I'd DIY some cool gear instead and buy something off ebay.

If you wan't it's easy to make something out off voltage regulator datasheets. I also got some variable highvoltage designs, but they tend to get elaborate if you don't want a huge dissipation (sp?). I've also seen several of those designs blow up. High voltage and transistors don't match well. You could build something with 6AS7 or 6550 tubes but that gets exspensive fast! Again, surpluss Lambdas would be smarter.

I did see a nifty circut in Sound Practices with one of those dual triode/power tubes (6BM8?) that could give you 150-350V/50mA I think. That would be easy and cheap to make. I'll see if I can dig it up.. :?

Well, I wasn't trying to make a fully variable, do-all-be-all supply. Just something that would be useful.

I wasn't saying +100 to +250 variable, I was saying a choice of the two. Those two values seem to be pretty common in many tube circuits I've looked at.

For the lower voltages, making, say, a +/-18, +/-24, and +6.3 for heaters wouldn't be terribly hard. No variability there, either, but do you really need it? Everything I make would ultimately get its own power supply anyway.

I suppose the other way to do it would be to make small and easy power supplies for different voltages. Say, a +/-18, then a +48 for phantom, etc.

Well if you stick to a 100V & a 250V + variable 2x12-24V it could be done somewhat easy. Just use the Gyraf double trannie trick and a seperate trannie for the low voltage stuff.

I would still recommend a seperate heater supply.

I also got some variable highvoltage designs, but they tend to get elaborate if you don't want a huge dissipation (sp?). I've also seen several of those designs blow up. High voltage and transistors don't match well. You could build something with 6AS7 or 6550 tubes but that gets exspensive fast!

Click to expand...

I have the schematic+info of my old bakelite Philips HT-supply (145-315 reg., 0.1 A). Can scan schematic etc, but anybody heard of the 4699N ?

Don't know which currents you're thinking about, but I recall having also seen a circuit with EL84 as the pass-device.

4699N a tube? Never heard about it!

[quote author="sismofyt"]I did see a nifty circut in Sound Practices with one of those dual triode/power tubes (6BM8?) that could give you 150-350V/50mA I think. That would be easy and cheap to make. I'll see if I can dig it up.. :?[/quote]
If you can't find it I have it.

Best regards,

Mikkel C. Simonsen

[quote author="sismofyt"]4699N a tube? Never heard about it![/quote]
Read all about it here: http://www.jogis-roehrenbude.de/EL34-Story/EL34-Story.htm

Best regards,

Mikkel C. Simonsen

Group;
I might be wrong but their is a whole industry (T&M)
that does this as their only business.
I think it may be usefull to use their work instead of DIY.
DIY audio not bench supplies!
I do not say audio supplies for equipment that IS DIY land.

Try HP (Agilent), Kepco, Lambda, and may others.
I get mine at swap meets for .10 (ten cents) on the dollar.
never paid over $80 for a supply.

Buy it not build it.

This piece of crap puts out :

1 ea. 5 vdc
5 ea. 6 volt at 1 amp dc heater supplies
5 ea. 12 volt at 1 amp dc heater suppies
1 ea. 24 volt relay supply
1 ea. 48 vdc phantom
1 ea. 250 volt B+ 5Y3 supply
1 ea. 250 volt variable B+ gas regulated Fairchild supply

I have a seperate chassis for +/- solid state supply

So you can get a lot of pwr supplies on one chassis.
Six pwr transformers, two chokes, etc etc
cj
x
x

z


:guinness:

I picked one up like this about a year ago.

Low voltage PSU can be found on #bay for cheap eg. Less than 24V, 12V, 9V, 5V......since they are the most commonly used and easily to be obtained, which are not really worth building. Whereas high voltage PSU are not as common and they are usually big and heavy(iron), becomes very expensive for people outside of US due to shipping.

For anyone who is interested and will be looking into building tube gears they'll need a HV PSU, I can't seem to find any quick & cheap solution besides building it. :?

Am currently learning about HV regulators using TL783, got a transformer that puts out 550Vp-p and I want to use fig.20 on the data sheet

http://focus.ti.com/lit/ds/symlink/tl783.pdf

The transistors TIPL762

http://www.angliac.co.uk/st/data_from_st/1029.pdf

Anyone have any advise on using my transformer with fig.20 on the data sheet? I guess one major problem would be heat dissapation?

thanks!

Thanx for the EL34 history link, Mikkel. Quite a nice site :grin: Can't find the ECL82/6BM8 Sound Practices regulator... do you have it scanned?

[quote author="sismofyt"]do you have it scanned?[/quote]
Yes, here you are:

http://stiftsbogtrykkeriet.dk/~mcs/SP3-017.gif
http://stiftsbogtrykkeriet.dk/~mcs/SP3-018.gif

Best regards,

Mikkel C. Simonsen

Yup, that's the one! Tak :wink:

ECL82s are dirt cheap, so it could be a cool trick to try with preamps etc.