It became so popular that the ATtiny85 even got packaged into USB dongle formfactors, like the DigiSpark boards. Well, you might not know this, but your Android smartphones can also work with USB ...

Although [David Johnson-Davies] has a couple of multimeters lying around, he still felt the urge to build a stand-alone continuity tester and has posted details for a super-simple ATtiny85 based ...