[sdiy] NEWBIE REQUEST; PIEZOS

[Toby Paddock]

NIKOLAS,
I've been doing some of that lately too. Fun stuff.
I used 1/4" mono jacks and plugged them into my radio shack mixer 
mic inputs set to -20dB. They are very sensitive. Insanely sensitive. 
I'm hoping that I don't blow the mixer input. It also worked using the 
line input to make it less sensitive.

For the mono jacks, the metal base disk went to the sleeve for ground 
and the top thin metal contact went to tip. For stereo, both base disks 
to sleeve, one top contact to ring, the other to tip. Mmmmm... stereo. 
I'm having good luck with 2 mics on one metal thing for stereo.

I will probably add back to back diodes across it to limit the voltage to 
0.7V for protection. If I held the piezo around the edge and thumped 
it with a pen, I got something like 30V.

I think you should be able to add a capacitor across it to lower the 
voltage. My (questionable) theory is that they are a charge source 
and capacitor. Adding capacitance will lower the voltage and not 
change the frequency response (much). Also should make it less 
sensitive to loading by the resistance of the mixer input. 
Haven't tried it yet.

Good luck and I'd like to hear how things work out.

 - -- -  Toby Paddock

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From: 	PATTERSON[SMTP:sanpatts at ozemail.com.au]
Sent: 	Saturday, June 02, 2001 3:39 AM
To: 	synth-diy at node12b53.a2000.nl
Subject: 	[sdiy] NEWBIE REQUEST; PIEZOS

Hey all,

My first post to this list!

To cut to the chase, I am looking to 'mic' up some metal, and associated
materials. I have some Piezo Electric Transducers, and some 1/4" jacks, mono
and stereo.

I can solder alright, and that is no trouble.

My question is; is it okay to wire the Piezos to the jack, and patch that
into my mixer, amp, speakers? Or, do I need a circuit, power (psu) or
something else? Can you please offer your suggestions, circuits, or
what-not?

Further, what is the ring/tip/sleeve configuration on a standard 1/4" jack?

Any, and all help would be great!

Thanks heaps,

NIKOLAS