1 Attachment(s)
Audible continuity tester
I wrote before about squeezing the last electron out of batteries with voltage too low to power some equipment...
https://www.homemadetools.net/forum/...041#post160654
Sadly, my supply of geriatric, not dead but tottering, batteries is not yet exhausted. While looking for other electronic items, I stumbled across a miniature 3 volt buzzer. It gave me an idea to build an audible continuity tester. Now I've built such beasts before...
https://www.homemadetools.net/forum/...807#post100081
but such sophistication is not always required or desirable. I'd hate to accidentally poke the that one into a powered circuit and blow it.
How about a dead simple battery and a buzzer ? Touch the leads to something conductive and it makes a noise; you don't have to be watching it to see if you have a circuit, you hear it*. Get it across a powered connection and you blow maybe $1 worth of parts. Well not really a whole buck. Every part in this device was found lying around the house in various boxes of parts and wires - even the empty pill container that houses it. Total time to construct was 27 minutes (yes, I timed it), and that involved soldering and using the hot air gun to shrink some shrink tube.
Nitpickers may notice I'm using 4 AA batteries, ie 6 nominal volts, to power a 3 volt buzzer. Remember, all these batteries are sub-power, the open-circuit voltage of the four pack is about 4.7 volts. Beyond that, the buzzers are very tolerant of input power and, if it's a bit loud, I'm an old man with poor hearing and tinnitus. :-)
Attachment 36138
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* If you're checking continuity inside a live box, this property could well save your life. DAMHIKT.
