(AT)Tiny Continuity Tester

A well-equipped electronics laboratory will feature a wide array of test equipment. But the end of the day — whether you're a novice or expert — a lot of electronics work is a matter of poking contacts to see if they directly connect with each other. This sort of continuity tester functionality is built into nearly any multimeter, but if you’d like something even more convenient for this job, the Tiny Continuity Tester, as explained by David Johnson-Davies on Technoblogy, looks like an excellent solution.

The device features a flying lead that can be poked onto a circuit or plugged into a breadboard, along with a PCB body that holds the battery, an ATtiny202 microcontroller, a piezo buzzer, and the probe itself, a dressmaking pin with the point slightly blunted. There’s also an indicator LED for good measure. The simple circuit and components are formed into a nice pointy package, making it easy to maneuver around for measurements, and it passes less than .1mA through the circuit under test to avoid affecting sensitive components.

Johnson-Davies' purpose-built device has no on/off switch, but instead goes to sleep when idle 60 seconds. With a standby power consumption of less than .04µA, its CR1025 coin cell battery should last for several years.

While the example tester runs on an ATtiny202 in an SOIC form factor, the program/PCB setup should work with any eight-pin chip in the ATtiny 0- or 1-series. The continuity tester is an upgrade to Johnson-Davies' 2017 project here, and the pointy PCB probe design is also reminiscent of his LED tester that we featured previously.