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Bryan 1st December 2005 09:51 PM

Benchtop PS
Does anyone know of a good benchtop power supply to use for testing and prototyping tube gear?

Some recomendations on units would be great!



Sherman 1st December 2005 10:32 PM

Re: Benchtop PS

Originally posted by Bryan
Does anyone know of a good benchtop power supply to use for testing and prototyping tube gear?

Some recomendations on units would be great!



I can't tell you if it is any good as it just arrived this afternoon but I just purchased a vintage Heathkit that supplies HV DC, 6.3VAC and has a splitter, I suppose for bias voltage.

The 6.3VAC taps are rated for 3A, the HV DC is rated for 100mA. I put a meter on it this afternoon and with no load the HV taps are adjustable from 192V to 426V. Should be good for prototyping many types of amps, at least one channel anyway.

If I could change anything about it (not even having done anything other than powering it up and putting a meter on it) it would be having a built-in voltmeter and possibly also an amp meter. Those would be features worth having I think.

I think I paid about $30 plus shipping of $15 or so.

Check that auction site but try a bunch of different searches as these suckers are listed in a bunch of different categories and with a bunch of different descriptions.

Zen Mod 1st December 2005 10:38 PM

Burnedfingers 1st December 2005 10:50 PM

I have several like this one.

ISCO 494 Electrophoresis Power Supply, 2000V, 300mA NR

It does everything except for the heater supply.

Bryan 2nd December 2005 01:34 AM

Funny you mention an electrophoresis PS.

Earlier this evening I was looking at the Bio-Rad units we use for Western Blots and Agarose DNA gels, thinking to myself "now this would be MUCH better used in my apt than this lab....."

I'll keep my eyes open for any being thrown away at work.

In the interim, what are some good models to look out for on ebay etc?



Burnedfingers 2nd December 2005 01:57 AM

There is a ISCO 493 Electrophoresis Power Supply, on ebay now for $30.

Usually the electrophoresis power supplys can be purchased cheap. They make a nice bench buddy.

jackinnj 2nd December 2005 02:51 AM

The Heath IP-17 uses a voltage-doubler -- it's pretty darn good as a supply. I modded mine for use with a micro-controller, took out the 6L6's etc. and refashioned it with an AD825 error amplifier and a pair of big MOSFET's.

You can also pick up an Eico of the same vintage.

gotta new design in the works...

powertriode 2nd December 2005 04:57 PM

The best bar none is the Fluke 407.

anatech 2nd December 2005 11:18 PM

I have a Heathkit PS-3, and a Lambda 6-281G. I use the Heathkit mostly.

Hey, what ever you have that works is the best, bar none. Generally, any of these will be better than the supply the project gets built with in the end.


Valverine 3rd December 2005 12:48 AM

DIY Bench PS
Starting down (up?) the path of building tube amps I figured that the among the first things I'd need is a good bench PS. But I decided to make it also DIY, inspired by an article on the great site (thanks, George!). The idea is to get involved in learning/building off the bat and make a useful thing along the way.

The PS should be "extensive" enough to support future amp projects and hereby the spec is something like this:

1. Two HT channels, up to 600V, variable. One for driver stage - 100 ma is plenty; the second for output stage, higher current. I don't rule out a 3-channel amp in the future, so the current ratings should cover this possibility.

2. A bias supply, up to 120V (this is a usual variac range)

3. Two heater supplies, up to 12.6V, variable, few good amps rating.

And everything regulated so here is where the questions come in...

I was able to find few schematics for low voltage, high current variable supplies. But for HT did not get too much hits, the majority was for something like 12-24V. One HT was designed by jackinnj (post above), but the digital part confuses me and at the level of my electronics education it will be tough to mod the circuit appropriately. The second circuit is much simpler, but does not go up the ratings that I need. So here are the questions:

1. It looks like the limiting factor in that circuit is the regulator IC; if I substitute it for one used in jackinnj (e.g., IRFPG40) what is the right way to re-calculare the other component values?

2. Is it a possibility to insert the regulating circuit between the variac and the control transformer (meaning the variac + transformer arrangement as at tubelab)? It looks that this way the regulator itself doesn't need to be that high voltage (120V max). Is there an additional benefit that the inductance of the control transformer will act as a smooting choke?

3. Is there a need in a smoothing choke or will regulator itself be a sufficient ripple-killer in case it goes after both transformers?

Any tips/suggestions/pointers will be greatly appreciated.


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