Help for electronics dummies in making your own unit

I have tried to make a unit using the suggested 10k potentiometer and also the suggested Radio Shack multimeter.

Here’s my problem. I can’t get the multimeter to read any reduction in voltage when I run the circuit through the potentiometer. When I select the lowest amperage setting, I get no reading.

There are three lugs on the potentiometer, I used the outer-most two and wired it in series.

Can anybody help?



There’s a difference between Voltage and Amperage. You won’t see the change in Voltage (especially when wired in series), so set the meter to the lowest amperage setting, e.g. 2ma.

Yes, there are three lugs on the potentiometer. You would normally connect one wire to the center and the other to one of the other lugs (one would increase resistance as you turn the dial clockwise, the other lug would decrease the resistance as you turn the dial clockwise). You can check this with the Ohm section of your meter. Normally for this application, you’ll want to use the lug that decreases resistance as you turn the dial clockwise (less resistance will rusult in more amperage). Attaching the wires to the 2 outermost lugs will not work.

Thanks NoHair! That helps a lot.

It also appears (after having read the instructions for the meter) that the section of the meter that measures miliamps is fused and that the fuse is quite sensitive. I think this unit came with a blown fuse.

I will rewire and return the meter to Radio Shack for one that works.

Thanks again,


You always have to be careful when wiring a meter in series and setting it to the amps section. It is very easy to overload it and ruin the entire meter (for example, having it in the amp section and touching the two poles of a battery will most likely destroy the meter). There are probably words to this effect in the manual for the meter.

nohair would you build me a machine ??? Whatever you think your time is worth. I have no knowledge of electronics. if you dont want to I understand

I do not have the time to build additional units.

Little knowledge of electronics is needed. The device is extremely simple and requires mechanical aptitude in putting parts into a project box. The parts form one simple circuit and battery polarity is about all you could get wrong. Leave out the meter and practice with the variable resistors. Any electrical information is available at