Question: Testing wallwart voltage.

[muehring56]

How do you test an adaptor with a dmm to make sure it is putting out the right voltage?

[petemoore]

Here's how
 Set the DMM to 20vDC range, taste a fresh battery and apply the leads to the battery, when you see something around 9V you're meter can most probably be safely said to be measuring DCv with 'relative accuracy.
 now put the DMM leads on the PS's output - and + , it should read your DC voltage. Hooking the PS to a circuit will load it and cause the voltage potential to drop a little. Remeasure to find out how much.

[Paul Perry (Frostwave)]

It is almost worth making a chunk of test harness for testing warts, a socket and plug arranged so that it is easy to get at the voltages while the wart is connected to the device in question, and also arranged so that it is easy to measure the current drawn. Yeah I can hold the leads onto one battery snap and a battery while the other 1/2 is plugged in (to measure current) but, it is impossible to do this with a wart plug.
(if anyone DOES make a test rig, please put up a pic so peopel can tell what I am trying to say )

[JHS]

With a good DMM, that's accurate enough. The 0.1% or 0.2-error don't bother me much.

JHS

[gtech]

Some serious reading...

http://www.qsl.net/ke3fl/htm/WALLWART.HTM