Project 026 - DMM Continuity Tester
DISCLAIMER: This design is experimental, so if you decide to build one yourself then you are on your own, I can't be held responsible for any problems/issues/damage/injury that may occur if you decide to follow this build and make one yourself.
DMM Continuity Tester V1.0
Watching YouTube videos where Multimeter reviewers reach the stage where they test the continuity beep mode of the meter by 'clicking' the probes together as fast as they can to see if they can beat the 'beep' into submission.....I thought "there must be a better way than that".
So, I immediately thought of producing a small circuit to short the probes together (p-type FET) and release in quick succession and on top of that provide a display where the timing can be adjusted. All thats required from that point is the reviewers ear to listen for the beep repeat falling apart.
I also wanted to produce a circuit that would be my first KiCad 6.0 Pcb after jumping ship from Altium CicuitStudio. Out of all this came the DMM Continuity Tester V1.0.
An Arduino Pro Mini (5V) provides the processor, switch interface and LCD drive.
A laser cut front panel finishes it off, and all that's required other than a few cables and standoffs is a 9V battery.
I have made it all open source on a strictly non-commercial basis. So here's the Code, PCB gerbers etc, BOM and Front Panel file here: FILES.
Or, in regards to the code, if you are having trouble installing/compiling the libraries etc then here's the hex file here: HEX, Avrdudess can be used to upload it to the Pro-Mini using your own programmer of choice.
EEVblog Forum thread: https://www.eevblog.com/forum/projects/dmm-continuity-tester-v1-0-better-than-clicking-probes-together!/
The design could go a lot further I guess:
- Add a microphone to measure response time.
- Increase the speed so the likes of the BM786 can be measured (Use 16bit PWM or perhaps an STM32).
- Add some arbitary type modes, i.e. mimic running along 10pins of a connector.
- Add more output FETs with various different resistances to mimic crap probes etc.
- Anything else!
