The Micronta probe, disassembled

Back in the 1970s, I owned a Micronta (an old Radio Shack brand) logic probe. It's a small device that lets you see if a wire in a digital circuit is carrying a 1 or a 0 (represented by 5 volts or 0 volts).

When my logic probe hit 30 years old, it must've decided, as so many people do, that life was all downhill from here. It stopped working. Inspired by the do-it-yourself philosophy, I wanted to build my own replacement rather than buy one.

A fellow named Luhan Monat had designed a Super Probe, based on a PIC microcontroller, and posted the schematic and code online. Not only is it a logic probe, but it's a frequency generator, capacitance and inductance meter, voltmeter, signal generator (pulse width modulation, square wave, UART, infra-red, video, and MIDI signals), and more! Luhan: you rock!

My Super Probe circuit board

I built a probe to his schematic. I reused the power cord, probe pin and ground jack from the old Micronta case. The end result was too big to go back into the Micronta case, so I decided to build a new one.

The wooden case

I bought a block of bocote wood - an exotic wood available at places like Woodcraft and Rockler. I cut the block to size, used a router to round the edges, then cut the block open with a band saw. I hollowed out the inside on a router table and cut the window with a jigsaw. A red filter from scientificsonline.com covers the window.

The Super Probe in action