MATH’S NOTES

Simple Homebrew Test Equipment Revisited

Last June, we presented a simple homebrew field-strength meter to encourage novice experimenter to try to build something. The response was overwhelming. We followed this up with some simple test equipment that the same group could attempt. Again, the response was high so, since there is some sort of interest in doing something “hands on” (thank God!), here we go again.

Most DVMs (digital voltmeters) do a good job measuring resistance but sometimes values lower than 10 ohms cause all sorts of problems with soldered connections, contact closure resistance, length is a very low resistance meter with a full scale range of 0-10 ohms. It works in conjunction with your DVM and will actually measure resistance values from 0-10 ohms with a resolution approaching 0.001 ohms, depending on the DVM you have. Obviously, you will need to calibrate this so it is a good idea to have a precision 1- or 10-ohm resistor on hand.