Testing 12V items

CharlieWaffles · #1 02-23-2011, 12:14 PM

As I build, I'd like to have a 12V power source I can use to test items as otherwise they will sit in storage until everything is fired up. Plus I'd like to test servos as they get assembled, etc... Is there an option other than buying a normal aircraft battery and possibly draining it over time, or is there some 12V AC-DC power converters that should work for light AMP testing?

Mike S · #2 02-23-2011, 12:25 PM

I did all my testing with a deep cycle marine battery I had sitting around. I made up a set of leads about 8' long from some 10 awg wire I had, so the battery could be out of the way.

Charge it once in a while as needed.

BE SURE to double check polarity when you hook it up------polarity never changes when all you do is flip a switch, but when you have to hook things up every time you want juice,,,

mburch · #3 02-23-2011, 12:34 PM

I have two bench power supplies, one fixed-voltage and one variable. Based on my experience, I can recommend either one:

mcb

JonJay · #4 02-23-2011, 12:40 PM

I found a very nice 13.8vdc regulated 10A avionics bench supply there for $125. You dont need to spend that much but this was a $400 plus piece of gear new.

Av8torTom · #5 02-23-2011, 12:49 PM

Check around your house. If you're like me you have a drawer full of AC adapters that were used to charge or power an electronic gizmo you once had. Look on the back and see that it's putting out 12 volts DC (or close to it) and somewhere between 5-10 amps.

RV10Rob · #6 02-23-2011, 01:09 PM

I've used this one, with good results.
http://www.amazon.com/gp/product/B0002BA57A

mattsmith · #7 02-23-2011, 01:14 PM

To test servos and lights I just used a 9 volt battery, wont last long and of course this will only work for the small stuff.

rapid_ascent · #8 02-23-2011, 02:08 PM

There are a lot of different bench power supplies that will do the job or even a car battery as suggested. One word of caution though is normally you wouldn't want to do your initial testing with a supply that can provide a large amount of current. A supply with current limiting is suggested. A car battery for example can provide a huge amount of current and by the time you figure out that you have something wired wrong it may be too late. A bench supply with adjustable current limiting would be the best, and you should set it as low as possible. A smaller supply with a low current output may be OK too. If you have a more basic larger supply then I would suggest you put a quickblow fuse in-line. If you did your wiring perfectly then it won't matter, but if you didn't you could be very sorry if you don't limit the current.

I bring up a lot of new circuits as part of my work and I always try to turn the current limit down as far as possible when I start. I have seen a technician miss wire a piece of equipment, put is head in the unit, and turn it on. Well let's just say he won't be doing that again. Melted wire, nasty smoke, scared the ... out of him.

Anyway its always a good idea to limit the downside.

1911pilot · #9 02-23-2011, 02:15 PM

I use these at work for a few different things. http://www.mcmelectronics.com/produc...-8110-/72-8110

They come set at 13.8VDC but they are adjustable. Very stable and for what they are very cheap.

FYI, a 12VDC unregulated power supply (cheap wall warts) can easily put out well over 16 volts depending on the wall outlet voltage. Meter it sometime, it can be very surprising.

roee · #10 02-23-2011, 04:44 PM

A very inexpensive solution is to use an ATX power supply (standard power supply used inside desktop computers). Low end ones can be had for under $20. Or for free if you happen to have an old junk computer laying around.

These power supplies have a big wire harness with a number of different voltages, so be sure to tap into the correct wires (+12V, ground). The connector pinouts are standard, and can be found easily with a Google search. And double check with a multimeter before you hook anything up!

Current ratings upwards of 10 A @ +12 V are not uncommon, but they do vary between different products (the current rating is NOT standardized!), so be sure to check that the supply you get will meet your needs. Note that the current ratings are specified individually for each of the output voltages, so be sure to check the current rating specifically for the +12 V output.