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Old Jul 15, 2003, 10:50 PM
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Walled Lake, MI, USA
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Adjustable Voltage Power Supply Question

I was considering ordering a Pyramid PS-21KX regulated 12V 20A power supply for $59.99 from etronics.com to power my battery chargers. Then I noticed below it a Pyramid PS-26KX regulated adjustable voltage 25A power supply for $25 more -- $84.99.

I'm still learning about electronics, so I may be off base here. But would it be possible to use this adjustable voltage power supply for static testing motors and props? I've been doing static testing with battery packs. But I was thinking that perhaps an adjustable voltage power supply would be better as it would hold a steady voltage and make A-B testing more accurate.

Am I on the right track here, or is another device different from this adjustable voltage power supply required for static testing motors? If the PS-26KX could serve a dual purpose of running battery chargers as well as supplying power for static testing, it would be worth the extra $25 to me.

http://etronics.resultspage.com/disp...wersupply&rk=5
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Old Jul 15, 2003, 11:58 PM
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SF Bay Area, CA
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It would be OK, but a PS that allowed voltage adjustment down to zero and adjustable current would be much better. There are times when limiting the amount of current can save a motor, battery, or whatever. Otherwise, if a connected motor, battery or whatever shorts out, the PS will dump up to it's 25 amp limit into it and let out the smoke really fast. Also, the lower voltage limit of 6 volts is too high for breaking-in a motor or some other uses. I use a power supply that is rated 0-24 volts, 0-12 amps. I have another rated at 0-20 volts, 0-50 amps. With these adjustments, I can even charge Li-ion/poly cells without fear.
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Old Jul 16, 2003, 02:28 AM
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Los Angeles, California
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Quote:
Originally posted by babblefish
I have another rated at 0-20 volts, 0-50 amps. With these adjustments, I
Who makes this? How much did that cost you? That's my ideal PS to get.
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Old Jul 16, 2003, 08:04 AM
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Quote:
Originally posted by aau007
Who makes this? How much did that cost you? That's my ideal PS to get.
It's an lab quality industrial power supply made by Electronics Measurements, Inc. The dimensions are 17"x19"x3.5" and weighs about 50 lbs. - not very transportable, although it does have handles. I bought it used for $75 at an electronics flea market in San Jose, California. The guy I bought it from also had about a dozen 0-20 volt, 0-25 amp supplies for $50 each. I work in the electronics industry, so I know a PS of this type normally sells for about $1,500 new. Guess I got lucky.
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Old Jul 16, 2003, 08:20 AM
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Marietta, GA
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.. exactly - unless you're very lucky, it will cost $1000 or more for a 50A unit!
..a
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Old Jul 16, 2003, 09:20 AM
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Walled Lake, MI, USA
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Babblefish, I appreciate the info on the lab quality industrial power supply. I'm looking for a quality adjustable power supply in the $100 range. I really don't want a 50-pound monster. I'm willing to put up with the shortcomings of a non-lab quality, non-industrial unit. Do you have any opinion on the Pyramid PS-26KX or similar alternative?
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Old Jul 16, 2003, 09:21 AM
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Joined Jan 2002
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I found this text in another thread for a programmable power supply

Instek power supply is about $232.00. They vary by volts/amps; more volts, lower charge rate. here is a link:
http://www.tequipment.net/InstekPSP405.html
that's 40 volts @ 5 amps
They have 20volts @ 10amps and 60 volts @ 3.5amps

Kelvin
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Old Jul 16, 2003, 04:47 PM
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Quote:
Originally posted by Dave Hederich
Babblefish, I appreciate the info on the lab quality industrial power supply. I'm looking for a quality adjustable power supply in the $100 range. I really don't want a 50-pound monster. I'm willing to put up with the shortcomings of a non-lab quality, non-industrial unit. Do you have any opinion on the Pyramid PS-26KX or similar alternative?
Dave,
I gave my thoughts on the PS-26KX in my first response to your thread.
Also, I hope you don't think I was boasting about what I use - I just wanted to point out that it is possible to find very good power supplies for reasonable prices if one looks around. Unfortunately, good supplies with adjustable voltage/current AND high current capabilities are going to be expensive, lab quaility or not. So the only other alternative is to either buy used or make your own. I'll certainly keep my eyes open for something suitable and inform everyone if I run across any. In the meantime, see if there is a magazine called "Nuts & Volts" in your area. This is an electronics enthusiast magazine and has ads from vendors who sell new and surplus electronic equipment.

-Wes
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Old Jul 16, 2003, 04:54 PM
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Quote:
Originally posted by aau007
Who makes this? How much did that cost you? That's my ideal PS to get.
I see you're in the Southern Calif area. There used to be a lot of high tech companies around that area so check to see if there are any electronics surplus stores that might have a suitable PS. One that I know of is All Electronics:

905 S. Vermont Ave
Los Angeles, CA 90006
213-380-8000

or

14928 Oxnard St.
Van Nuys, CA 91411
818-997-1806

Also check the fleamarkets, you'll never know what you'll find there.
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Old Jul 16, 2003, 09:26 PM
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Walled Lake, MI, USA
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Wes, ahh, yes. "OK." It's easy to miss two letters sometimes.

No, I didn't think you were boasting. I figured you probably know a lot more about electronic equipment than I do, and make good use of equipment that might be more than I really need to accomplish what I want to really accomplish. I wouldn't feel comfortable buying a sophisticated piece of used equipment that costs as much as or more than a new piece of equipment with fewer capabilities. If something went wrong with a used piece of sophisticated equipment, I wouldn't know what the heck to do with it. And getting it fixed would likely be more expensive than buying it in the first place. I like to wade in the ocean before jumping in.

I'm taking your "OK" as a sign that the PS-26KX will do what I need, but it isn't what you would buy for yourself. Fair enough. As long as Pyramid is a reasonable brand and $84.99 is a decent price, that's all I need to hear. Thanks for your help.
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Old Jul 16, 2003, 10:24 PM
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Los Angeles, California
Joined Apr 2002
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Quote:
Originally posted by babblefish
I see you're in the Southern Calif area. There used to be a lot of high tech companies around that area so check to see if there are any electronics surplus stores that might have a suitable PS. One that I know of is All Electronics:

905 S. Vermont Ave
Los Angeles, CA 90006
213-380-8000

or

14928 Oxnard St.
Van Nuys, CA 91411
818-997-1806

Also check the fleamarkets, you'll never know what you'll find there.
Thanks for the info. I know the one on Vermont but have long forgotten about them. I will check there first.
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Old Jul 16, 2003, 11:35 PM
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Wichita,Ks
Joined Jul 2003
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www.radios4you.com/powersupplies.html . Just bought a Mastech HY3005D-3. Dual 0-30 volt, 0-5A, adjustable constant current, adjustable constant voltage. Can be run in serial or parallel mode for 0-60 volts at 5 amps or 0-30 volts at 10 amps. Chinese, heavy, appears to be well built, works well with my nicad packs, probably will work to charge large LiPo packs when I work up to them. Easier than programming a Schulze. I have added a fan. Depending on how much power you want, 90-260 bucks gets you a new, lab-quality power supply. Found them on E-Bay, transaction went well.
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Old Jul 17, 2003, 01:52 PM
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Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
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Dave,

I have been using that same Mastech adjustable power supply for nearly two years. I love it. It is great for doing static tests and for powering a variety of things. It never leaves my workbench. I would recommend this one over the $85 version you mentioned at the top of this thread. It's an investment I have never regretted.

Gordon
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Old Jul 17, 2003, 11:25 PM
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Walled Lake, MI, USA
Joined Feb 2000
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Gordon, I've come around to appreciating the value of an adjustable current model. I know that you mostly work with small motors that would not exceed 10A, and that's pretty much where I've been focused. But what happens if you ever want to test something that draws more than 10A? You've pretty much limited yourself. Yet to buy one that handles more than 10A gets even more expensive. I think I'll continue to study and think about this for awhile to make sure that I make the right longterm investment. I'm pretty confident now that I will be flying electric for a long time, so it will pay to invest properly for the longterm.

Wes, I see the wisdom of your original message now. Thanks. And thanks to everyone else for your good input.
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Old Jul 18, 2003, 08:28 AM
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SF Bay Area, CA
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Good luck with your search and I'll keep my eyes (all three) open for one(some).
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