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jes1510
12-10-2008, 12:15 PM
My old benchtop supply is finally getting to be unreliable enough that it annoys me. Th regulation is pretty bad and it is just getting really old.

I am getting a paycheck from a contract job and want to get a new power supply. I am considering this one:
http://www.circuitspecialists.com/prod.itml/icOid/8770

I am not dead set on it and would welcome suggestions for alternatives. The specs do meet what I want (0-30VDC, O-5A, %V @ 1A) for a reasonable price. Thoughts?

4mem8
12-10-2008, 12:40 PM
Well, If I were going for a new P/S I would go for this one http://www.circuitspecialists.com/prod.itml/icOid/3511 I don't know how many times I have needed a dual P/S, I know it is a bit more expensive but well worth it in the long run, But I guess it's all about budget and you have to get what you can afford. I know it's rated at 3amp and not 5 amp as you have in your above P/S, But with robot electronic testing how many times do you need 5amps?. I know I don't.

jes1510
12-10-2008, 01:39 PM
Hmmm excellent point. I came by the 5A number because it was not that much more expensive then the 3A model. You definitely bring up a good point about the dual supplies as well. Now I am considering this one: http://www.circuitspecialists.com/prod.itml/icOid/3506

I was hoping to get a power supply and a function generator for around $400.

Adrenalynn
12-10-2008, 04:03 PM
How often do you need 5A? Every time you fire up any of the robots I've seen you build, 4mem. And then some.

The Crustcrawler arm will pull more than 5A at load. A single widdle toy motor can drive up 5A before you blink - and that's before you stall it. A single 805BB servo can pull a couple amps when stalled.

jes1510
12-10-2008, 04:28 PM
Yeah that was pretty much my concern but I hadn't even thought of the dual supplies. The second one I posted can be put in parallel to supply 6A.

Adrenalynn
12-10-2008, 05:18 PM
Have you poked around on eBay yet to see what you can get a working HP or Gould or Tek for? I tend to buy my test equipment that way, then spend a few dollars more and just have it shipped straight to a calibration or recertification house...

metaform3d
12-11-2008, 01:09 AM
I'm probably an idiot to chime in on a topic of which I know so little -- however, when I needed power for testing I went online and bought a 480W computer power supply for about $20. It gives me 3.3, 5 and 12 volts which is pretty much all I ever need. At 12v it claims 17A.

I'm honestly interested to know why I should pay 10x the cost for apparently lower specs.

Adrenalynn
12-11-2008, 01:34 AM
Adjustable voltage, nicely packaged.

A computer power supply isn't bad, really. Watch the 3.3v line, they tend not to be which is why mobos have so much regulation and filtering. I have a couple with a switch soldered inline. Make sure you have a decent load on the 12v line before you power it on, otherwise they like to blow themselves up.

4mem8
12-11-2008, 05:55 AM
How often do you need 5A? Every time you fire up any of the robots I've seen you build, 4mem. And then some.

The Crustcrawler arm will pull more than 5A at load. A single widdle toy motor can drive up 5A before you blink - and that's before you stall it. A single 805BB servo can pull a couple amps when stalled.

Adrenalynn: True, If you are using it to power dc motors and servos, I was more refering to just testing my digital/analogue circuits, I have another P/S if I want to test my Dc Motors rated at 10amps with a variable voltage of 0-50v. Computer P/S supplies are pretty good,They are usually switch mode systems, meaning you have to have a load on them when switched on. I have used them for testing purposes. But dual supplies I use most of.

4mem8
12-11-2008, 06:02 AM
Hmmm excellent point. I came by the 5A number because it was not that much more expensive then the 3A model. You definitely bring up a good point about the dual supplies as well. Now I am considering this one: http://www.circuitspecialists.com/prod.itml/icOid/3506

I was hoping to get a power supply and a function generator for around $400.


Yeah, I saw that one as well jess1510, That would be ok, just depends on what you want to test, As Adrenalynn states, using it for powering Dc motors or servos can soon up the amps.

Connor
12-11-2008, 12:05 PM
This one http://www.circuitspecialists.com/prod.itml/icOid/8769 can be put in 10Amps Parallel mode.

Sienna
12-11-2008, 12:11 PM
Personally, I am considering something like this:
http://www.universal-radio.com/catalog/hamps/3344.html
I am looking at power supplies I can use with a bot full of high-power servos.

jes1510
12-11-2008, 12:30 PM
Personally, I am considering something like this:
http://www.universal-radio.com/catalog/hamps/3344.html
I am looking at power supplies I can use with a bot full of high-power servos.

Wow that thing is a beast. It is a bit noisy with 10mV of ripple. Also it would kick the breakers in my house when loaded but it does look great for powering motors.

Adrenalynn
12-11-2008, 12:45 PM
I doubt it'd kick too many breakers since its AC requirements should be in the 5A range...

As far as the ripple and drift goes - your electronics are probably filtered and regulated anyway, right? At some stage you're probably running from battery which would require it be regulated, and if the regulator doesn't have a couple filter caps - well - it's a bad design.

Nice find, Sienna!

4mem8
12-11-2008, 12:48 PM
Good for motors and servos Sienna, As I said before, it all depends on what you want to use it for, That's why I have three P/S supplies, A single 0-50v 10 amp [ motors and servos] and a dual P/S +5v, -5v,+12v, -12v, +15v,+18v, +5v,+12v,+15,+18v all at 3amps for testing circuits, -5v and -12v for op amps @0.6amp.

jes1510
12-11-2008, 01:03 PM
I doubt it'd kick too many breakers since its AC requirements should be in the 5A range...

As far as the ripple and drift goes - your electronics are probably filtered and regulated anyway, right? At some stage you're probably running from battery which would require it be regulated, and if the regulator doesn't have a couple filter caps - well - it's a bad design.

Nice find, Sienna!

Holy crap remind me to actually check my calculations before posting. Thanks for the correction.

Adrenalynn
12-11-2008, 02:26 PM
Well, I'm just guessing. And throwing a lot of loss in there. If it was 30A @ 15v, I just whacked 3A @ 150v out of my head, and then figured half again for loss in conversion...

Figure something like 500wt, right? A 500wt PC power supply delivers about 25A on the 5v rail and 20A on the 12v rail...

Anyway, no exact numbers are possible because we don't know efficiency. We can't do much more than take a stab at it and guess it's like running a couple PCs.

Alex
12-11-2008, 02:29 PM
[moved to power forum]

ScuD
12-11-2008, 04:33 PM
Being an electronics guy, up to this day I still use either an old AT-style PC power supply (with a big red plastic tab switch that goes WHOMP when you flick it) and a few leftover wall-warts for prototyping, which is... well sad to say the least.

Though pc power supplies suffice when testing higher power loads (like loads of servo's or motors) you really need to make sure the power rails on the electronics side are well filtered.
But unless you're using a lot of analog electronics in your designs, they work fine.

My point is, your power supply should depend on what you plan on doing with it. If you're doing your own electronics designs, you may want a "real" PS with selectable current cut-off and low ripple, but generally speaking the massive current draw can come from a different rail that doesn't need the same accuracy as your control electronics do.

Out of curiosity I checked a local "supplier" where I can get cheap electronics parts. 125 for a 12V 66A power supply. Hmm.. :veryhappy:

jes1510
12-11-2008, 05:01 PM
Being an electronics guy, up to this day I still use either an old AT-style PC power supply (with a big red plastic tab switch that goes WHOMP when you flick it) and a few leftover wall-warts for prototyping, which is... well sad to say the least.

Though pc power supplies suffice when testing higher power loads (like loads of servo's or motors) you really need to make sure the power rails on the electronics side are well filtered.
But unless you're using a lot of analog electronics in your designs, they work fine.

My point is, your power supply should depend on what you plan on doing with it. If you're doing your own electronics designs, you may want a "real" PS with selectable current cut-off and low ripple, but generally speaking the massive current draw can come from a different rail that doesn't need the same accuracy as your control electronics do.

Out of curiosity I checked a local "supplier" where I can get cheap electronics parts. 125 for a 12V 66A power supply. Hmm.. :veryhappy:

Unfortunately I have to use it for stuff other than robots. Right now I am designing a circuit that uses a 100kHz oscillator at pretty low amplitudes so I need a pretty clean power supply.

I have a stack (literally) of old ATX power supplies so I could always use some of them if I need big juice for a motor.