How to add a buzzer to a digital multi meter

Thread Starter

LAOADAM

Joined Nov 21, 2018
273
I have a master-craft multi meter 052-0055-6, that don't have a buzzer, but there is a 'beep' printed on the main PCB board. is that possible to add a buzzer in it?
 

Tonyr1084

Joined Sep 24, 2015
5,039
I would suspect the PCB was designed to be used in several different configurations. It's likely the "BEEP" is intended for a higher end meter. However, simply adding some circuitry to your current meter could very well change how it reads voltages, resistances and amperages.

If you want a simple continuity tester you can build a simple test rig using a coin cell battery and an LED. No resistor needed. AND you can use OLD coin cells, as I've done some testing on how long they last with an LED connected directly to the battery. Old used batteries can last for weeks at continuous operation. So using them to indicate continuity would work quite well. As long as you don't introduce an extra voltage to the tester or to the circuit you're testing out.

If you use this tester on a battery you'll blow out the LED in short order. IF you test a very highly sensitive circuit with this tester you can blow out your circuit. If you want an audible tester you can configure an optical isolator (Opto-isolator) you can use the output to trigger a BJT that triggers either a relay that drives a buzzer OR if the buzzer current doesn't exceed the BJT's rating you can drive it directly from the transistor.

I have a bunch of brand new 1632 coin batteries that have expired (can't do the job they were intended for). They drive a superbright LED with no problem at all. I just may build one of these testers myself. Thanks for the idea.
 

jpanhalt

Joined Jan 18, 2008
10,219
What other test equipment do you have? Put an oscilloscope/multimeter from the beep to its other terminal or ground and see whether there is any signal there.

Presumably, if the device is not ancient, it has an MCU. If I were making that device in at least 2 versions by the 1000's, I would be sure the program for the MCU was blocked from the beep function to prevent people from doing exactly what you seem to contemplate doing. That is why I would check for any signal first.
 

MisterBill2

Joined Jan 23, 2018
6,997
If there is a beep continuity tester function and you hear nothing then perhaps the sounder has failed, or the connection to it has failed or been removed. Some folks dislike that beep whenever they turn the switch. So the beeper may just have been disabled. I would not attempt to add a beeper to a working digital meter because of the very high probability of destroying it.
 

MaxHeadRoom

Joined Jul 18, 2013
21,402
I would agree with @Tonyr1084 that the unit has a option for a different model.
The meter itself does not have the beep feature as it comes.
Master Craft is mainly Chinese origin now, but for the price of the meter I would have expected it.
A few more $$'s and you could have a Fluke.
Max.
 

MisterBill2

Joined Jan 23, 2018
6,997
If there is only a beep printed on the circuit board but not a beep position on the mode selector switch, then probably a continuity beeper mode is not available. At one time some meters had a beep when a reading stabilized function, it might work for that if you added a beeper to the terminals. But most likely the function is not available in the meter software for that model.
 

MaxHeadRoom

Joined Jul 18, 2013
21,402
For the price of that meter I would have expected the usual buzzer/diode check scale.
My Fluke will buzz continuously up to a certain low ohmage, the intermittent up to another resistance point then nothing after that.
Max.
 

Tonyr1084

Joined Sep 24, 2015
5,039
In the many years I've inspected PCB's, populated and bare boards, I've seen plenty of times whole sections of the board NOT populated because a feature was not ordered by a customer. IF the customer should decide they wanted that option they didn't have to build a whole new board; all they had to do was add the extra components. PCB - 1 rev A might be only 4 of 7 inputs whereas PCB - 2 rev A might be for 6 inputs. It's still the same board, just a different BOM (Bill Of Materials).
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
273
Thanks for all replies.
I'll try some thing later on.
The 'BEEP' besides two empty PCB terminal holes should be left for higher lever product like Tony side. I like the coin batteries idea very much.
 
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