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Continuity Tester for Codger...

Jobewan

Mar 26, 2018
1
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Mar 26, 2018
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Hey All,

As I get older my high end hearing is leaving me. One of the more annoying places this is an issue is when troubleshooting continuity on a circuit. I used to rely on hearing the beep from my meter, but I can no longer hear it. I have purchased a few devices, namely a couple of bench top DMMs, as well as a couple of different handheld DMMs, to see if maybe one of them would have a better buzzer element. - no luck. I guess I could hack my older Fluke 45 bench top meter and take the output out to some LED device I could throw together, or to a small amp that would lower the pitch and increase the volume. But before I did all of that I was wondering if anyone out here has an answer. This has to be a problem that a lot of us codgers have experienced. My hearing loss is age related. I don't want to wear hearing aids, although I may get there regardless.

Anyway - let me know if you have any ideas? Love to hear from anyone else who has had this issue and dealt with it somehow.

Thanks in Advance

Joe
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
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If I were in that situation I'd probably make a simple circuit that illuminated a bright LED when there was continuity (or near continuity).
 

kellys_eye

Jun 25, 2010
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I'd also go with the LED device - potentially something that produced a 'sliding scale' (column of lights perhaps?). Using different colours in the column would be easily observed even at the periphery of vision.
 

WHONOES

May 20, 2017
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If you just want to register continuity below a certain value it should be fairly straight forward using a battery, a cheap comparator and a bright LED.
 

Braeden Hamson

Feb 18, 2016
240
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Feb 18, 2016
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240
You could even open up your meter and replace the buzzer with an LED. Drill a hole in the case and put the LED in there. Good luck finding out the voltage of the buzzer with your DMM in pieces :D
 

FuZZ1L0G1C

Mar 25, 2014
366
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Mar 25, 2014
Messages
366
If you don't wish to do surgery on your DMM's, maybe as already suggested above, use an electret mike?
I first considered an inductive pickup, but as most DMM's use Piezo transducers, threw that idea out.
Running with the electret idea, here are some graphics examples.
The basic idea is to amplify, square off (clip at VCC), rectify, and use resulting pulsed DC to drive an SCR etc.
Added the Bandpass amplifier (wrongly labelled it 'notch' in sketch) as an optional extra in case ambient noises cause false triggering.
Top oscillogram shows (A) noise picked up by E-mic; (B) Bandpass amplified and squared; (C) Rectified to DC - - -
Second graphic shows layout idea(s).
Third is the Bandpass designed here for 1.2KHz but can be modded for other BP center f.
 

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  • twin-t_feedback_bandpass_amplifier.gif
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Braeden Hamson

Feb 18, 2016
240
Joined
Feb 18, 2016
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240
If you don't wish to do surgery on your DMM's, maybe as already suggested above

Maybe I'm a little over zealous about chopping things to bits. I once bought a brand new joystick and never plugged it in, just chopped it up and modded it.
 
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