Replies to This Discussion

Permalink Reply by Dianne Woods on July 4, 2010 at 12:32pm

MadGomer, I am sorry I can't help you, but I am sure someone will come to your rescue soon. Welcome.

Permalink Reply by petey twofinger on July 5, 2010 at 12:11pm

should be fine , you only want the disk , not the other parts .

you COULD do a "test" , you know , hook it up to an amp , tap on it , that would require effort so nevermind .

Permalink Reply by petey twofinger on July 5, 2010 at 12:13pm

i have never noticed a piezo with 3 ponts .

do you have a continuity tester ?

oop s that goes back to effort .

i waste time here .

Permalink Reply by MadGomer on July 5, 2010 at 3:40pm

Yeah I know, I'm pathetic. Haven't built my amp yet, so can't fiddle with that (but it gives me an excuse to go round up those parts - yes!) Will give the continuity tester a try, but not exactly sure what I'm looking for at this point. Will probably just swing by RS again & buy a different piezo that doesn't have the board in it - I can always use the other one on the next build after I figure it out. If I can find my camera I'll post a picture of the disk showing the three connections.

Permalink Reply by Don Thompson on July 5, 2010 at 11:11pm

Ignore the circuit part. Solder the red wire to the tip of the jack. Black to the shaft tab.
Don

Permalink Reply by MichaelS Country Boy Guitars on July 6, 2010 at 12:47am

You just need the one wire that comes from the center of the piezo and one that comes off the edge metal area. do away with the little circuit board, save it for decoration.

Permalink Reply by Fitzhugh on July 6, 2010 at 9:20am

I just pried the buzzer out of a smoke alarm and found three contacts on the piezo. When tap testing it with each combination I get two distinct sounds, one fuller and lower and one much more on the treble end. I think it was made to make two different noises, so is really two peizos combined. Tell me if this sounds wrong to anyone. The alarm made both chirp noises when the battery was low and, of course, the horrid ear splitting alarm noise. I wonder if I can (easily) ad a knob to mix between the two as a pseudo tone knob?

Perhaps your piezo is like this. I'll post photos in a little while.

Permalink Reply by petey twofinger on July 6, 2010 at 9:30am

i googled dual tone piezo , saw one that said "constant and beeping tones" , i guess i would do a test , maybe you could use a switch or even get lucky with your pot idea .

you may get best results doing it in parallel .

youd have to monkey around .

never saw one with 3 wires though .

Permalink Reply by MadGomer on July 6, 2010 at 12:32pm

Here's a fuzzy photo to take a look at. The lead coming off the metal goes to black, the lead on the large white area is going to the M terminal on the board, and the lead from the smaller white area goes to the "F" terminal.

petey twofinger said:

i googled dual tone piezo , saw one that said "constant and beeping tones" , i guess i would do a test , maybe you could use a switch or even get lucky with your pot idea .


you may get best results doing it in parallel .

youd have to monkey around .

never saw one with 3 wires though .

Permalink Reply by petey twofinger on July 6, 2010 at 9:43pm

sure , that lil section would seem to have a lesser or at least different freq response .

mess around with it and let us know what gives .

maybe i will run into one of those someday .

Permalink Reply by Mark on July 6, 2010 at 10:49pm

I think I might have figured out what you've got. The piezos with two sections (and three leads) seem to be designed for use in buzzers which work on the basis of what is known as "self drive oscillation mode". See the following diagram from the Velleman website:

I think what happens is that one part of the disc (presumably the bigger section) works as a speaker while the other section works as a pickup. All you then need is a simple bit of electronics to create a feedback loop with some amplification in it and the unit will generate a tone.

The alternative way to make a piezo buzzer is with the plain two-lead piezos we are more familiar with, where you just use the unit in a similar way to a speaker.

Permalink Reply by Fitzhugh on July 6, 2010 at 11:02pm

The photo almost matches what I have, differing only in inconsequential details, while the diagram certainly does. Seems like you (and I) have a self-driving piezo, and the feedback mechanism sure makes sense.

This was my first time amping my first cbg so when I tripped over the wire and pulled loose one soldered connection I had to just ignore it and play and play and never got around to re-soldering the wire. It was the small section. I do think combining the two might be worth it since the tones were different. I'll try tomorrow.


thanks for posting the explanation.

• ‹ Previous
• 1
• 2
• Next ›
• Page