This Vibrating Continuity Tester Is Quietly Useful

Continuity testing is one of the most valuable functions on the modern multimeter. It will help you investigate wiring problems in your car, tell you if you’re holding a nullmodem serial cable or the regular kind, and even reveal when you’ve accidentally shorted the data lines right to the power supply. However, all that beeping can get annoying, so [bitelxux] built a vibrating version instead.

The build was borne out of necessity; [bitelxux]’s meter lacked a buzzer, and it grew frustrating to always look at the display. In order to allow late night hacking sessions to go on undisturbed, an unobtrusive vibrating tester was desired, as opposed to the usual audible type. Two whiteboard markers donated their shells to the hack, fitted with small nails to act as probes. Inside, a pager vibration motor is connected, vibrating when continuity is found. The circuit runs from a 1.5V AA battery which neatly fits inside the marker shell.

It’s a basic build, but gets the job done with a minimum of fuss using parts that most makers probably have lying around. Of course, you can always go a slightly more complicated route and throw an Attiny at the problem.

21 thoughts on “This Vibrating Continuity Tester Is Quietly Useful

  1. This is a great idea! I have severe hearing loss, and that led to losing the ability to hear higher frequencies. I thought my trusty audible continuity meter had broken, in fact. Haptic feedback would be a great thing!

    1. This, yes!
      A good cotinuity tester should use a very small voltage, so that electronic components, even Schottky diodes, are not turned on, so in the order of less than 100mV. And of course, push a very small current.

    2. Yeah, I was hoping to see a conventional continuity test circuit that triggered a separate circuit with the motor. But it’s just a battery and motor directly in series with whatever you’re testing. Fine if you’re working on a motorcycle from the seventies I guess, but use it on anything solid-state and you’re probably going to screw it up by placing rapidly-changing inductive loads right in line with transistors and such. Could definitely use a bit more sophistication.

  2. Nice idea, well done for being first here, variations also worth considering, such as different types of feedback for:-
    a. Voltage free continuity range, strong vibration vs scale of pulsing approx related to resistance/impedance – along lines of comment by BrotherSaidPooh
    b. AC volts detected; random vibration akin to arcing sense more pronounced indicating more dangerous volts
    c. DC volts detected; vibrate in pwm mode at say 1 Hz to within selected range ie. Low volts short vibe per sec to high volts long vibe per sec etc
    d. Braille option where fingers rest and some short pins pop up in 1, 2, 5 step range
    More variants possible and still with useful utility such as two vibrators at opposite ends, programmable to suit user. These days voice activation/menu select easy (for limited number of words) or even pitch, ie low Hmm means let me know continuity only vs high pitch Hmm ! to indicated let me know volts etc…

  3. hmm i think it would work for most things, but all of the current and voltage of the motor is going arround through the measured object. but if there is lets say a diode in the way or a small resistor it would still rumble…

    does anyone know what voltage a normal multimeter is using and what resistence is still accepted as continuity?

    i would thing something below 0.3V and below 10Ohm would maybe be a good area – but that would require a sperate detection circiut that drives the motor…

    cool idea anyway!

  4. Terrible idea. How many times have you felt your phone vibrate in your pocket only to find that it hadn’t? Touch is one of the easiest misled senses. Light or sound are much less prone to ‘imagined’ stimulus.

    1. In this instance, the vibrator would be held firmly in your hand (as opposed to loose in your pocket) and you’d be actively waiting for haptic feedback. I’d expect far fewer ‘imagined’ readings, especially as you’d expect them to continue while you hold the probe in position.

    2. ??

      You’re holding the leads in your hands, and you’re literally feeling for the vibration. Maybe if you just rode 250 miles on a Vespa scooter at highway speeds…

      No-look and no-hands lab tools are awesome. When I get a neural AR implant, the first thing I’m gonna do is hack on a VGA cable so I can hook it up to my oscilloscope so that I don’t have to look up/down/up/down/up/down when probing stuff.

    1. Where do you think he got the motor from?
      Of course this means he won’t be having any more late night hacking sessions at least until she gets a replacement. Or until she figures out what happened to her old one in which case he will be having nothing but hacking sessions to fill his late night hours.

  5. The humble continuity tester is an underappreciated tool for sure. I always look for audible continuity on every meter I buy; and no, all that beeping does not get annoying, if you’re the one doing the testing.

    So this is a pretty useful idea! Running the pager vibrator current through the tested circuit is ok for basic and “durable” circuitry, like wire-tracing, automotive, etc, but I would prefer a buffer circuit so that the current is minimised. I would also add a bright red LED near the tip as well.

    The pager-vibrator has one disadvantage compared to a beeper: it doesn’t respond as fast. With a beeper, you can hear subtleties like intermittents and poor or failing contact.

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