Quiet a Piezo Transducer

No, it didn't. I just held a few resistors in there with alligator clips. The one that gave the desired amplitude was then soldered in :-)

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Regards, Joerg

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Seems like an awfully tedious way to go about it, trying all those resistors one by one till you find the one that's just right.

Much easier to sweep the preset pot through its range for the sweet spot, measure it and pull one single restistor from the parts drawers.

Ya, well, it's just a piezo :-)

Seriously, I think I picked a 10k and that muffled it too much, then a

4.7k or so and it was just fine. It was more or less the same effort as pounding in a nail ...

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I guess being lazy makes me do things the most efficient way I can think of.

No, I was the lazy one here. Resistors where right there in front of me. A potmeter would have meant a trip to the lab :-)

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Try using a stack of them. That makes THEM "in series" mechanically. Stand off the edges a few thou, and couple the centers with a small drop of epoxy. Or just buy a stack. Fire all those, or wire them so they all fire, and modulate, baby! Find the resonance points and stay away from them, or risk coupling destruction. Fun to play with home made versions.

Real stacks are super cool. You can squeeze a 4 inch tall, 64 element stack on its ends,, and it will pipe out HV on the leads.

Of course this stack takes up to 800 Volts to fire it full amplitude.

That stack could move a lathe head with such speed and precision that it could cut a square pin from a round nib on the end of the lathe. At several hundred RPMs. It was able to move that head, after a 1.3x lever ratio, a full millimeter.

The drive supply (mine) was 20 to 20k Hz. There are two 2kVA transformers in the base of the machine. The heatsink upstairs on the amplifier is nearly 2 feet long. It is tubular and air blows through the inside of it across several bunches of splayed tines inside the tube. The other side has over 20 monster devices attached to it. 1200V IGBTs and the like. Zero distortion. Drives the Piezo stack with 800 volt swings. That was a fun design.

My resistors are in component drawers all sorted so I know where to find any particular value.

Being lazy I prefer not to have piles of resistors laying about that I have to sort into values and return to their drawers..

"Sort into values"? I *never* return parts to storage. Once they've left the packaging they get pitched. Even the most expensive parts are a *lot* cheaper than my time debugging bad or wrong parts, down the road. Well, maybe not some Xilinx parts, but I don't take them out of their packaging anyway.

So do I. But I have something else that's rather practical: In a drawer there are few standard values, a couple of diodes, and so on. Plus the big resistor drawer rack was right in front of me, the more fancy parts like pots and transistors in the lab storage area.

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