Short Circuits and Continuity: Building an Easy Continuity Tester

RE: Short Circuits and Continuity: Building an Easy Continuity Tester

shabaz — Tue, 24 Mar 2026 12:29:39 GMT

I'm strongly considering doing a version 2 of this project. It works well so far, but I was wondering if I ought to have added a couple of TVS diodes at pin 1 and pin 5 of the quad op-amp. Also, I was thinking of a larger PCB, with mounted right-angle banana sockets, to eliminate annoying need for off-board wiring. Any suggestions for a low-cost plastic enclosure would be appreciated. I'd also move to AA cells (the AAA last forever but may as well make use of a larger size enclosure).

Also, it would be nice to have an adjustable frequency tone, and maybe even amplitude.. could use an audio amp and a larger speaker. This would make it better for people who cannot hear certain tones easily.

Another important requirement is an LED indication (sometimes audio cannot be heard in a noisy environment) - don't know how to best design that, maybe just driven from the same monostable, or a separate monostable with a longer period?

I want to keep it non-microcontroller based.

Any suggestions/ideas welcome!.

EDIT: Might also be worth swapping out power switch to a rotary knob, with settings: Off-LED-LEDplusLowVolume-LEDplusHighVolume perhaps..

RE: Short Circuits and Continuity: Building an Easy Continuity Tester

Jan Cumps — Thu, 27 Feb 2025 23:43:33 GMT

EEVBlog just released a related video today:

[View:https://youtu.be/9lC-k5yU9W4:640:360]

Discusses latch times and hysteresis ranges

RE: Short Circuits and Continuity: Building an Easy Continuity Tester

genebren — Thu, 27 Feb 2025 20:00:07 GMT

I noticed your comment about the "tight squeeze", and I wondered it something like this would help with the assembly?

They are 4mm Banana jacks. I used these on [mention:9268afb21bfb410f8d8af2c4a191ed3a:f7d226abd59f475c9d224a79e3f0ec07] You might be able to use a solder lug around the threaded part to attach to the PCB. They are a little beefy for this application, but they just might take up less sapce.

RE: Short Circuits and Continuity: Building an Easy Continuity Tester

DAB — Thu, 27 Feb 2025 19:45:31 GMT

Very nice post.

I still remember the very simple continuity testers that came out and soon proved to be not very useful.

RE: Short Circuits and Continuity: Building an Easy Continuity Tester

genebren — Wed, 26 Feb 2025 23:18:23 GMT

Very cool [mention:b0bc65b9ecdc4307bd967592f00e340a:e9ed411860ed4f2ba0265705b8793d05] ! Thanks for sharing your results. It seems like the 3 to 18 ohms range is perfect for the application.