Simple dummy load for testing?

Started by zpyder, June 11, 2007, 02:16:43 PM

Previous topic - Next topic

zpyder

Hey everybody...

I've got a mixer that runs off of a 12VDC wall wart that will not power up.  I would like to test the wall wart before opening the mixer... with a volt meter I can register ~ 12.6VDC, but I'm wondering if perhaps it's not giving out enough amperage...?  What is the simplest way to test this?  I was figuring I could create a simple circuit that presented a dummy load to the supply, and then measure the DC across the circuit.  But I'm not sure if this would work or how exactly to do it.

Any help would be sweet

thanks
zpyder
www.mattrabe.com/ultraterrestrial Ultraterrestrial - Just doing our little part to make new rock go where it should have gone in the late-90's, instead of the bullshit you hear on the radio today.

Tubebass

You just need a resistor. Use the formula R=E/I, where R is your resistor in ohms, E is the rated voltage of your wall wart, and I is the rated current of your wall wart in amperes. So if it is a 500 ma wall wart, a 25 ohm resistor should load it to its capacity. Your resistor will need to dissipate 12 volts x rated current, so for a 500 ma wart, your resistor will dissipate 6 watts. It would be best to use at least a 10 watt resistor in this case. Hope this helps.
More dynamics????? I'm playing as loud as I can!

km-r

ergh... 12v lightbulb and connect a ampere-meter in series...
Look at it this way- everyone rags on air guitar here because everyone can play guitar.  If we were on a lawn mower forum, air guitar would be okay and they would ridicule air mowing.

zpyder

yikes... with my wart rated at 3.6 amps I'd need a 44+ watt resistor...

ill try the lightbulb method
www.mattrabe.com/ultraterrestrial Ultraterrestrial - Just doing our little part to make new rock go where it should have gone in the late-90's, instead of the bullshit you hear on the radio today.