For my first post to the forums I have a design of mine to present. The basic premise is that the piezo element is situated under the skin of a drum (bass drum for example) and that when struck, the resulting voltage switches the FET and thus the LED array (also located inside the drum) on for as long as the piezo element is recieving enough of a pressure wave (drum still making sound).
The circuit diagram I have attached has been put together from my limited high school electronics knowledge, an online LED calculator and a piezo switch circuit I found at http://www.discovercircuits.com/DJ-Circuits/piezoswitch2.htm
The value of the cap has been changed to reduce the LED 'on' time from about 0.5s to 0.05s
A few questions however:
Due to the relative speed at which drums can be played, I want a fast decay. is the capacitor the only thing constraining this?
I read that the sensitivity of the piezo can be adjusted with a variable resistor in parallel with the element, hence the 1M variable in the circuit, is this correct or is there a better way? also, wont the variable resistor also effect the timing of the LED 'on' period?
Is the output of the Piezo likely to be big enough to exceed the 20V rating of the FET?
I am planning to use a 6V wall wart transformer, is this likely to give me shockingly bad DC that will adversley affect the circuit?
Anything glaringly obvious I have missed?
Cheers.
Marcus Sargent
Invercargill, New Zealand.
The circuit diagram I have attached has been put together from my limited high school electronics knowledge, an online LED calculator and a piezo switch circuit I found at http://www.discovercircuits.com/DJ-Circuits/piezoswitch2.htm
The value of the cap has been changed to reduce the LED 'on' time from about 0.5s to 0.05s
A few questions however:
Due to the relative speed at which drums can be played, I want a fast decay. is the capacitor the only thing constraining this?
I read that the sensitivity of the piezo can be adjusted with a variable resistor in parallel with the element, hence the 1M variable in the circuit, is this correct or is there a better way? also, wont the variable resistor also effect the timing of the LED 'on' period?
Is the output of the Piezo likely to be big enough to exceed the 20V rating of the FET?
I am planning to use a 6V wall wart transformer, is this likely to give me shockingly bad DC that will adversley affect the circuit?
Anything glaringly obvious I have missed?
Cheers.
Marcus Sargent
Invercargill, New Zealand.
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