diy lab supply

[jazz]

Hi there,

I'm currently working in a factory that makes all sorts of stuff (buildings etc) out of aluminum and hence my junkyard box is slowly getting filled with all sorts of aluminum parts that are left over. this got me thinkin about a lot of things i can do with it.

I decided the first thing i want to make with it is a lab psu. I've got a trannie, caps, coils and a couple a heatsinks good for about 100watts of dissipation. All the alu parts are there but not a design.

I remembered seeing some high current designs in the lm317/337 datasheets but when i looked them up i couldn't find them.

Could any of you point me to a design that is good for up to 20-30V (+ and -) and up to 4-6A using the parts mentioned?

I did a quick search but didn't find anything (yet).

Regards
Joris

[raidfibre]

The analog circuit you're referring to basically uses a bunch of cheap transistors [2n3055 usually] to follow the regulating device such as a lm317/137.

Have a look at this:
http://sound.westhost.com/project77.htm

[AndrewT]

Hi,
in this case fan cooling noise is not a problem.
As you reduce output voltage the dissipation increases badly.
Can you engineer a way for some relays to reduce the AC supply voltage to the circuit as you reduce output voltage? Maybe tappings on the secondary and/or primary windings.
regards Andrew T.

[raidfibre]

If you don't already "conveniently" have the correct windings for such a thing, you might as well build a switching regulator that will be MUCH more efficient. It isn't even that hard if you aren't worried about isolating the two outputs
(not necessary if you're already using a transformer with a center tapped secondary)

[Algar_emi]

I can just recommend my desing, see my website at:
http://pages.infinit.net/cyrberg/ps2.html

This is the power supply I'm using and it is just great, very versatile: 2X0-30V, 3A, Voltage or current constant modes, Integrated DVM, etc...

Bye...

[thomas997]

The opa549 will give you a 8 amp continous 10 amp peak supply.

But it says output only goes up 25V.

[jazz]

Hi,

thanks for the replies. I had a look around and did a further search. I already found the psu by rod elliot but it doesn't have enough muscle. Fan cooling will certainly be incorporated but in a switchable form. From early experiences i've learned to listen to the components first when they are first fired up; Funny mechanical noises (hum etc) and smells are to be avoided, hence i like silence when possible. I'm avoiding anything switching since i don't understand how it works and since this is supposed to be a simple excercise i don't want to learn. Algar's supply looks mighty impressive but i guess it would be to good for my purposes. It's just meant as a simple and flexible supply for start and testing procedures in prototyping stuff i want to build or just get to know, nothing fancy. the OPA suggestion is a nice one but indeed limited in it's voltage. I have two trannies with different voltages, both ct. I guess i can use em both and make em switchable.

Right now i've found a supply on this page i'm going to use:

http://logosfoundation.org/kursus/2007.html

It's the one with the lm317/337 and bdx66/67. With a crc or clc in front and some bypassing on the voltage setting circuit i think this will do. Now i only have to figure out how to incorporate voltage and amperage indicators, I'll get there.

Anyway thanks for the advice

Joris

[BeanAnimal]

A guy on ebay sells digital volt and amp panel meters. He will even include the shunts. They are about $10 each. Don't have the name off hand.


Secondly, eBay is a great source for used bench supplies. My question is... Has anybody used those NEW $69 suipplies that everybody on ebay seems to be selling. Are they any good?

Lastly, I am workin on PCBs for the design listed above. Not being a PCB designer, they could be scary!

Bean

[Kermit]

Originally posted by thomas997
The opa549 will give you a 8 amp continous 10 amp peak supply.

But it says output only goes up 25V.

I'm currently planning a supply using the opa549 and as far as I can tell opa549 can output (V+) -5v or thereabout. So with max supply voltage (60v) it can go up tp 55 volts. The app.example is shown with a 30v supply, thats way it wil only go up to 25v.
At least thats how i read the datasheet.

Cheers.

[thomas997]

Originally posted by Kermit


I'm currently planning a supply using the opa549 and as far as I can tell opa549 can output (V+) -5v or thereabout. So with max supply voltage (60v) it can go up tp 55 volts. The app.example is shown with a 30v supply, thats way it wil only go up to 25v.
At least thats how i read the datasheet.

Cheers.

oh ok

thanks