Man. So. Today, this happened. I was watching a new video from Adrian Black and his EEVBlog multimeter failed:
I have been saving my pennies and planning to buy an EEVBlog 121GW Multimeter because a lot of the makers around the interwebs have one as a nod to Dave Jones over on the EEVBlog, but that’s just so embarrassing that it’s failing. Of all the equipment you have you need to trust your test equipment the most and this is… well, just sad I guess.
Today we teardown a homemade continuity tester which I put together for use before I had a multimeter, so that was in the early days of my new lab, circa August 2021.
While I was preparing the links for this blog post I discovered that the plastic case I used for the continuity tester was the HB5610 Black Hand-held Electronic Enclosure from Jaycar. I purchased one of these for AU$9.95 back in August 2021, which was around the time that I made this continuity tester.
I subsequently purchased a ten pack of similar plastic cases from AliExpress for AU$64.55 (inc shipping) in March 2022. I went to find the AliExpress listing so I could link you to it, but it’s an old listing and has been taken down. I did search for an equivalent product but didn’t find what I was looking for. The dimensions are roughly 70mm x 135mm x 24mm and there is a facility for 2x AA batteries built in.
What I say in the video about active vs passive piezoelectric buzzers is correct. The active buzzer will do the buzzing for you, all you need to do is supply some power. The passive buzzer will need an input signal in addition to power, so some sort of oscillator if you want to generate a tone.
I knocked up a schematic for this continuity tester, something like this:
I’m gonna try getting some PCBs made for this circuit from PCBWay, because I’m still trying to learn everything I can about that process!
Here is a table of products I use which may appear in my video with affiliate links to vendors if you would like to buy. The link given here won’t necessarily have the best price so please do shop around to see if you can find a better deal. If you have thoughts or questions please feel free to let me know. Let’s go shopping!
When I was a kid I had a clumsy analog multimeter, and I would have been awed to have something like this. Now you can buy them for $5, so I got a whole bunch of them…
So I got myself a new toy from AliExpress: ANENG AN-999S Desktop Voice Multimeter Professional Digital Bluetooth 19999 Counts True RMS Auto Range DC/AC Meter (I got the ‘AN999S 4’ option with batteries and extras). It’s just a bench multimeter, but it has some cool features which make it a welcome addition to my workstation, which is that it has a built-in clock and thermomiter, and if you press the button on the COM lead it will speak the reading for you, which is pretty cool, and I guess means you don’t have to look away from the circuit to get your reading. Look forward to playing with this one, definitely a happy customer so far.