Cheap DMM.

Thread Starter

zophas

Joined Jul 16, 2021
157
I bought a real cheap DMM and was surprised that it already had a 9v battery installed but disappointed that it does not have a continuity setting. I think it's the kind of meter they give away at some hardware stores in the States. My more expensive meter will not test a LED but this cheapo at least lights one up very dimly. Which is basically the reason I bought it but also just as a back up.
 

Tonyr1084

Joined Sep 24, 2015
6,608
If it checks resistance then it can be used to check continuity. Just touch the leads together and see what the reading is. It may be 0.07Ω. So when you check a wire for continuity, a short wire will read approximately the same thing. Longer wires will read higher resistance. You can calculate that by going to a wire chart to see what the ohmage per foot is, then multiply the distance (in feet) times whatever the chart is telling you, then add your 0.07Ω to that. If you use a wire that has 1 ohm per 100 feet and check for continuity, then 1.07 would indicate a "Continuity". If you have a pair of wires 100 feet long, same type wire, size and all, and short the two ends together, you will read 2.07Ω. Of course these numbers I just made up - you need to know what the resistance of your test leads are and what the ohmage per foot of the wire you are checking. Like I said, very short runs you probably don't have to worry about calculating the resistance. But you CAN check continuity with an ohm meter. As for checking LED's - I just grab an old coin cell. Strong enough to light one up but not so strong as to burn it out. In fact, I've powered an LED from an old coin cell for weeks before it finally grew too dim to detect with any kind of ambient light.
 

Thread Starter

zophas

Joined Jul 16, 2021
157
Yes, I should have specified "audible continuity checker" in my opening post. It sort of becomes second nature to listen for a beep when tracing on a PCB. But at least I still have my other meter for that. Thanks.
 

SamR

Joined Mar 19, 2019
3,834
Well for us deaf folks, the beep is useless! So we depend on the ohmmeter. The beep is often inaudible in industrial settings due to noise as well.
 

Ian Rogers

Joined Dec 12, 2012
966
I have a decent one... BUT!! when checking continuity and you think you found a fault!!! Only to find out the damn things gone to sleep... Ohms is better..
 

ErnieM

Joined Apr 24, 2011
8,216
One of my favorite features on my Fluke hand held meters is the diode test. It pumps out a few volts at not insignificant current such that it can safely light a LED by itself.
 
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