Elenco XP-720K (Cheap benchtop power supply recommendation)

[c0nsumer]

If any of you are looking for a cheap benchtop power supply for use when making your x0xb0x (or other electronics projects), you might want to check out the Elenco XP-720K. I found it from a place called KITS USA for $44.95, with reasonably priced and very prompt shipping.

I made a slightly in depth review of it over here in LiveJournal, or if you just want to skip ahead to photos of the power supply during various points while I was assembling it, take a look at my Elenco XP-720K photo gallery.

In short, it's trivial to build, was cheap, and seems to work as designed. In some brief testing I was also able to hit 2.000VDC exactly (if that DMM is to be trusted), although it could use some fine tuning controls added later on.

[stevenclements]

Hey that's looks pretty nice!

[c0nsumer]

Hey that's looks pretty nice!

It is, actually. The only change I'm making is replacing the pots with Bourns precision 10-turn wire-wound pots (P/N 652-3540S-1-202) from Mouser. They were $13/each which adds almost 50% to the cost of the supply, but it should allow for much finer control over the voltage. Oh, I also had to get some .25" set screw type knobs for it too, because the original pots have grooved shafts.

Oh, and I'm going to heatshrink the leads on the ICs. Check the photos for why.

-Steve

[stevenclements]

Hey that's looks pretty nice!

It is, actually. The only change I'm making is replacing the pots with Bourns precision 10-turn wire-wound pots (P/N 652-3540S-1-202) from Mouser. They were $13/each which adds almost 50% to the cost of the supply, but it should allow for much finer control over the voltage. Oh, I also had to get some .25" set screw type knobs for it too, because the original pots have grooved shafts.

Oh, and I'm going to heatshrink the leads on the ICs. Check the photos for why.

-Steve

Hmmm... I wonder if I would need the AC side of this. Probably only need a good varible DC power supply for 99% of the projects we come up against eh?

I mean do you find the variable AC ( Output AC: 1) 6.3VAC @ 1Amp, 2) 12.6VAC @ 1Amp Input: 110VAC ) useful?

cheers
Steven

[c0nsumer]

Hmmm... I wonder if I would need the AC side of this. Probably only need a good varible DC power supply for 99% of the projects we come up against eh?

I mean do you find the variable AC ( Output AC: 1) 6.3VAC @ 1Amp, 2) 12.6VAC @ 1Amp Input: 110VAC ) useful?

cheers
Steven

Actually, the AC isn't variable, and I haven't yet found a use for it. But then again, I've only had the meter for a week. I really only think that the DC side of things will get used a lot, but the AC is just a few extra lines off the transformer, I can see why they were included. Sort of a "why not"?

A dual output for US$45 isn't too bad, I don't think...

On Monday or Tuesday I'll be getting the new pots, so at that point I'll 'fix up' the meter. I'll probably have another few photos of it posted then...

-Steve

[stevenclements]

Hey Steve... what do you think of this power supply? Would this be a good one? It's all ready built

http://www.kitsusa.net/phpstore/html/HY-1802D-MASTECH-DIGITAL-POWER-SUPPLY-0-18VDC0-2A.html




Cheers

[c0nsumer]

Hey Steve... what do you think of this power supply? Would this be a good one? It's all ready built

http://www.kitsusa.net/phpstore/html/HY-1802D-MASTECH-DIGITAL-POWER-SUPPLY-0-18VDC0-2A.html




Cheers

I think it would probably be worth it, but to be honest, your DMM is probably going to be more accurate than those panel meters.

Personally, I'd still go with the kit, and get a pair of stackable banana plug leads and just run your DMM in parallel with the PS. Then you get the greater (albeit non-adjustable) amperage, AC out (if you need it), and the fun of building it. But that's just me.

-Steve

[stevenclements]

<SNIP>
I think it would probably be worth it, but to be honest, your DMM is probably going to be more accurate than those panel meters.

Personally, I'd still go with the kit, and get a pair of stackable banana plug leads and just run your DMM in parallel with the PS. Then you get the greater (albeit non-adjustable) amperage, AC out (if you need it), and the fun of building it. But that's just me.

-Steve

I just ordered it... quicker then building it and I've got issues with time

[c0nsumer]

I just ordered it... quicker then building it and I've got issues with time

Heh, that's cool... Let me know how it is. For what it's worth, with the 10-turn pots I was only able to hit 2.000VDC and 3.001VDC (per my meter) for tuning the offset in the x0xb0x. Sort of frustrated me... I'm likely going to drop in two small (maybe 20 Ohm) pots as 'fine tune' adjustments after I place my next Mouser / Digikey order.

Oh, and don't trust those panel meters... For tuning the offset, set the PS off your DMM, or at least confirm that they are accurate first.

-Steve

[alk509]

Actually, the AC isn't variable, and I haven't yet found a use for it.

Tube heaters, of course!

Peace,
Al.

[fluxor]

I have not yet built this supply. But I did stumble upon this page

http://www.io.com/~n5fc/xp720.htm

It has a nice panel meter mod. I also stumbled upon c0nsumer's photo album of the construction and modification of his unit.

[SmallWalrus]

Hey guys, I am thinking of getting this kit, however I live in a region where we use 220V mains voltage.

Does the transformer have any windings to make provision for 220V? For instance, some transformers have both 110V and 220V connectors on it's primary. I also noticed that quite a lot of things seem to be coming off the secondary, what connections are those for?

Perhaps I can swop out the transformer entirely if it is only for 110V, but I am not sure if I will be able to find a replacement!

[ericbnyc]

I assembled one of these, and I recently did the Bourns pots upgrades others above have mentioned. I'm really pleased with the device as a whole, it's solid, does what it's supposed to and I take pleasure in knowing I built it myself.