There are times when you unexpectedly need to check some sort of electronic element for integrity, wire or email. check the engine for breakdown in car check the fuse in the so-called traveling conditions, but you don’t have a multimeter at hand, and you won’t carry it with you everywhere, it’s not big ... The small compact tester Antoshka will help out (that's why one electrician called it in the good old Soviet times), which can be collected in a few minutes from a lighter with a flashlight and carried with you, takes up little space, and it's not a pity to lose. I would add a buzzer to it, but there was no suitable one for such a voltage ... Can someone tell me what to make a buzzer from? All the same, it is easier to react to sound than to light indication.
I wanted to make an old multimeter, but bulky because of the wires it turns out.
Made the easiest and fastest option, sealed the joints and shrink.
He put on a terminal block to prevent accidentally shorting wires in his pocket (which came to hand).
Good luck!