piezo transducer for EDrum

[kanni1303]

I am planned to build a project from the following link:
https://edrum.info fromt his link I made my PCB circuit.. with a slight changes I made the circuit to work fine with naked crytal(without any cover or others).. and I made a cover to my piezo crystal as attcahed in the photo, this was with a wooden piece cutted into round and piezo covered with a rubber(since I am going to hit the crystal with hand I chosed rubber that will make less pain to my fingers) but now the problem was I am not able to get signals from the crystal what I made with even a gain of 11 I fixed for the amplifier...
I can't suspect the crystal since the same setup was working fine with SPD-20 module( I bought from Roland) with my fingers...
I am not able to get any signal fromt the amplifier when I use it in my EDRUM project but the same crystal setup working fine with Roland SPD-20 module... what i lack from Roland module... should I increase the gain higher than this or something else I should make... I can't change the setup of crystal because it fits perfectly for my project and since it is working with accurate sensitive with Roland SPD-20 module...
Kindly poitn me where was the problem... All suggestions are welcomed in any degree...

 

[D.A.(Tony)Stewart]

Try a gain of 100. Any buffered CMOS gate with 1M feedback and cap to 10k series to inverting gate should work with AC coupled out.

Even an electret mic would work.

 

[kanni1303]

Is it acceptable that a gain can be raised to 100...???
can you pls elaborate about electret mic....???

 

[kanni1303]

I tested with even gain of 1000, where I am missing I don't know, should I look at the ADC part instead of looking at amplifier part... since the circuit works fine for others...???
What was the logic used in SPD-20 to boost the signal to that much level... the same drum pad was working fine the spd-20 board with sensitive... but when I hit too much hard also it is not capable to detect the signal....??? Pls help in getting this work with Piezo crystals....

- - - Updated - - -

The circuit diagram is **broken link removed**
and the Roland SPD-20 board is using some other technique to boost the signal....

I am getting a full range change of 0.500 mV to 0.530 mV change if I set a gain of 200 that is the difference is 0.030mV whicch is too low for my PIC ADC resolution...

Kindly do needfull

 

[D.A.(Tony)Stewart]

What levels do you get out of rectifier channel Vdc, with no sound and full sound? If not 0, 1V respectively , then we can go from there.

 

[kanni1303]

workign with 5V Vdc input for MC, 8V Vdc for OP-Amp... I need to check in the amplifier part alone... atleast if I get 1V diference then it will be fine... since I need to take three levels of input from piezo(light, medium and hard hit) shall I increase the voltage to op amp from 8V to 15V and try will that have an effect...???

If I hit on the piezo directly I am getting the signal difference upto 1V with gain of 10 but with the cover that what I made was not able to get even when the gain was 1000... But the same setup was working fine with that module... I am totally confused and stuck where and what I miss....