Introduction: Upgrading Old Multimeter With Buzzer

I have been using this multimeter since I know about electronics. I think that it is manifactured in 1974 so I am 1 year older than my multimeter. It is a durable tool and i decided to upgrade it with buzer circuit.

Step 1: Step: 1 I Found Buzzer Circuit on Net and Used It.

Part list for buzzer:
1. buzzer
2. led diode
3. transistor BC547B
4. resistor 220 ohm
5. resistor 330 ohm
6. resistor 1M ohm
7. switch
8. 3v battery, I used multimeter battery.

Step 2: Step 2: Dismount and Clean Inside

I dismounted it and cleaned all the contacts.

Step 3: Step 3: Placing New Circuit Inside

After cleaning I drilled holes for connectors for probes. Because there wasn't enough space for connectors I moved the fuse into fuse holder and use empty space for battery, where I put buzzer too.

Step 4: Step 4: Replacing Probe Connector

Old probe connector was broken and I replaced it.

Step 5: Step 4: Testing the Multimeter

Final tests.

And we are good to go.

Step 6:

Comments

author
pfred2 (author)2015-05-25

What makes the buzzer sound?

author
LordWader (author)pfred22015-05-26

The grey buzzer that you can see on picture on step 3, if that is your question. Or oscillation from the transistor when you connect the probes, as it is explained on schematics on step 1.

author
pfred2 (author)LordWader2015-05-26

By, "what makes the buzzer sound", I was trying to ask what condition caused the buzzer to sound? It is something that you may think you've explained, but you did not. You still really have not clearly either. Although right now I am assuming you mean when the probes have continuity to each other. Because, "connect the probes", usually means hook the probes up to equipment. As in plug the probes in.

author
LordWader (author)pfred22015-05-27

Ok maybe our misunderstanding is that English is not my native language. Buzzer circuit is continuity tester, and when you short circuit probes or test continuity on PCB, buzzer makes sound and diode lights up.

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