piezo microphone

[ninna]

hello!

i am trying to make acoustic instruments by using piezo pic-ups. I am very new to all of this, and I am wondering if anybody know; how will I get the best sound from my homemade microphone? I want to plug it to my mac, but I see somebody saying something about mic/line level input(?).

what is the difference between a preamplifier and an amplifier? do I need both? which is the best buy7or is it better to build it?

I have lots of questions... but I am very eager to learn more about this, (the electrics of sound and so on..)

please, can anybody help me??

thank you!!

[res07njc]

Piezos are transducers, meaning they convert mechanical energy (waves) into electrical energy. They are very easy to impliment, but there are some specifics to address at the 'line level' area.

They have a lot of impedance (z), so you will want to couple this to a preamp circuit that matches (or accepts) this high impedance. The Jfet works well in this area, and may be all that is needed if the piezo has high enough output on it's own. Experimenting will tell you the answer.

Google 'piezo preamp' for a schemtic of this type of circuit, with a jfet used in the 'follower' type of arragement. The follower will accept the high z, and output a new z that's more appropriate for the next piece of equipment (like the 'line in' of a computer, or a power amplifier if your wish is to make sound through a speaker.

9V battery power (along with the circuit) is all that is needed, and very 'doable' at the novice level. I would concentrate less on how or why anything works at this stage, and more on 'what' works. Shouldn't be too hard to DIY. Google.. take notes.. enjoy..

The jfet preamp should be mounted as close to the piezo as possible (or vice versa) btw..

If it's a guitar, this piezo preamp needs to be in the guitar... or drum.. double bass, or whatever it is that you are messing with..

[ninna]

Thank you thank you!!!

[d a o]

Maybe you can use this link
Noise free, balanced piezo microphone - Christian Liljedahl
Noise free, balanced piezo microphone

[scott wurcer]

There are several guitar sites that use a very simple (and cheap) J201 FET pre-amp, a good music store might stock the high value resistors they use in tone stacks.

[dheming]

For something a little different check out the CM-01B contact mic. It uses piezo film (PVDF) and has a preamplifier/buffer circuit built into the housing. It only needs 5VDC then you are good to go.