What's the best way to test mA on LEDs

What\'s the best way to test mA on LEDs

I've been doing LED flashlight conversions for a little while now but am having trouble figuring out how to read the mA of my LED lights. I made several AA maglights into LED lights by trimming the LED leads and replacing the stock bulb with it. I use three 1.5 volt N cells and a small spring at the end for power. Could someone please describe the proper way to set the meter and place the leads to read the mA going to the LED? Also I would like to check the voltage left in the light now and then but not sure how. Any help appreciated. Thanks.

Re: What\'s the best way to test mA on LEDs

Brad,
I've found that putting the meter leads in series with the load is easiest at the tail end of the flashlight. Just unscrew the cap, put one lead on the battery end, the other lead on the edge of the flashlight body. Having alligator clips help. For a meter I sometimes use a cheapo small VOM with a 150 milliamp scale. For greater accuracy or range almost any cheap DVM (digital volt meter) will do- most even have a fairly high current range. These meters now cost under $20, and sometimes less than $10. While they are not laboratory grade instruments, they are fine for hobby projects like this, and cost a fraction of what a name brand instrument would cost. The only thing I would like to stress about using any meter is be careful about using it in current mode- if you blow the internal fuse it is a hassle to change it. Once you've gotten the meter, you will probably need some specialized probes to hold the leads onto the work. I just do simple stuff so I simply soldered a small alligator clip onto one of the leads and use the other one's pointed probe. Fancy little grapplers are available that make holding onto tiny components easier so check them out at almost any electronics supply house.
Chet

Re: What\'s the best way to test mA on LEDs

Thanks for the help Chet. I will give that a try.

Re: What\'s the best way to test mA on LEDs

by the way Sears has a rugged digital meter (in a red soft 'case') for about $35 -- ahh love that Chinese slave labor...

Re: What\'s the best way to test mA on LEDs

I soldered the alligator clip to the positive lead. Works great. Thanks Chet.