Do you cruise the flea-markets looking for abandoned oscilloscopes to rescue? This signal generator key ring may make it easier to test the functionality of a scope when it doesn’t have any probes fitted.
Many oscilloscopes have the ubiquitous reference square wave generator hardware built in and simply connecting the probe to the test point and the earth connection allows you to test the scope functionality. Of course this is dependant on the scope having probes fitted which might not be the case with second hand units or ones found in the dumpster!
When you need to know a scope is functional before investing in some probes for it, this key ring has a really clever pin and PCB pad system that emulates a BNC connector, meaning it can be directly connected to a probe socket. It generates a sine wave via a Colpitts Resonant Oscillator, a type of oscillator that generates it’s feedback via a capacitance divider circuit and in itself is a fun oscillator to study.
Available in 10, 20 or 50 MHz varieties the Oscilloscope Tester Key ring can be powered from a CR2032 battery or via a USB powerbank.