Dear sir, I am not an electronics expert or even a hobbyist, I've been a professional musician for over 50 yrs. I built this unit with the intent to use it professionally but I need to get it to register the hits more accurately. I have been struggling with this for a long time. I can put circuits together but I don't have a scope or any test equipment. I would be externally grateful if someone could put up a diagram or add to the schematic above so that even a dummy could build it. I have several mcp6004s if they would work. Thank you.I think the piezo signal voltage will be so high that it destroys the input of the opamp. Use clamping diodes.
The opamp gain is 11 times which is much too high.
The diode forward voltage throws away a lot of the signal envelope, use an active peak detector (with the diode inside the negative feedback loop) instead.
Thank you all for replying, I'm using 20 mm piezos going into a teensy 3.6 board which has the DA converters and sends velocity sensitive signals to the software. It works with pull down resisters and clamping diodes but when I put a diode in series,(either before or after the op amp) it kills the velocity sensitivity. It works as is, the only problem comes when I play fast or drum roll, It doesn't register every hit. For example if I play bobady, bobady, bobady, bomp, it will skip the second hit of each bobady phrase as if it's still reading the first hit. There are 21 pads so the circuit in post #7 would cost over $50 just for the MCP602s,I see on the datasheet that the Cmos MCP602x rail-to-rail opamps have built-in voltage clamping diodes on their inputs, then the diodes I added are not needed.
I put the rectifying diode inside the negative feedback loop to cancel its forward voltage and my negative feedback causes the opamp to produce a linear representation of the signal envelope and its amplitude, not just simple full blast squarewave pulses from the comparator outputs shown on the Piezo Trigger circuit.
I don't know if you are confusing me with someone else or what but I never said anything about recording and playing back or anything else that's in your first paragraph. All I'm trying to do is make the piezo peak signal read more accurately.At first you said that the envelope of the signal is important, like the piezo is a microphone or vibration sensor then you want to record and playback those sounds.
But now you say the signals are digital and you are trying the comparators circuit in post #7, with the 0.6V rectifier threshold to overcome and higher levels are always at full blast like guns, not drums.
You do not understand that a comparator simply switches its output on and off and is not linear to variable levels. You also do not understand that a rectifier diode does nothing until the voltage becomes 0.6V or more and you do not understand that when I put the diode inside the negative feedback loop of an opamp then that problem is cancelled.
Isn't $50 almost nothing compared to buying 21 drum pads?
Then you want the rectifier diode inside the opamp negative feedback loop like I showed. Then the amplitude of each peak will be exactly what is played. The circuit in post #7 switches its output to maximum (less the 0.6V diode voltage) or nothing which is not accurate.All I'm trying to do is make the piezo peak signal read more accurately.
So you're saying I should try the circuit in post #5 ? if so which op amp? what resistors? All schottky diodes? You're right about all the things I don't understand, as I said in post #4. I have no background in electronics. This is the first and only circuit I ever tried to build. I don't have an assortment of components, I have a few things left over from my failed attempts but I have to order most of these. So if you think the circuit in post #5 would work could you please fill in the component values?Then you want the rectifier diode inside the opamp negative feedback loop like I showed. Then the amplitude of each peak will be exactly what is played. The circuit in post #7 switches its output to maximum (less the 0.6V diode voltage) or nothing which is not accurate.
View attachment 174503 View attachment 174504I do not know what the piezo signal must do. You said the function is to send "velocity sensitive signals to the software". Your schematic shows a "percussive envelope" and you say you want the peaks to be accurate.
1) How can a drum beat have "velocity"? When you hit softly then the output amplitude is low and when you hit hard the output amplitude is high. Then the envelope is important since it will have low, high or in between amplitudes and a simple diode in series will throw away the first 0.6V of the amplitude so a precision rectifier circuit I showed is needed.
2) What is the maximum amplitude so that the amount of opamp gain will be known? Resistor values determine the amount of gain.
3) Do you hit a piezo sensor or do you hit whatever the piezo sensor is mounted on?
4) Does the piezo and its mounting resonate for each hit like real drum membrane and must the resonance need to be eliminated so one hit does not make many outputs?
5) Do you simply want to "trigger" the software to do something for each drum hit?
|Thread starter||Similar threads||Forum||Replies||Date|
|K||PGA SD ADC and FFT resonant frequency of the measured signal by piezo sensor||Sensor Design & Implementation||0|
|F||Best approach to amplify piezo (self-generated) A/C signal at the 1mVAC level||General Electronics Chat||12|
|L||How to use an Analog Front End with Piezo for Ultrasound Signal Processing||General Electronics Chat||2|
|S||convert piezo signal to midi||Analog & Mixed-Signal Design||12|
|I||Piezo signal amplification circuit question||Analog & Mixed-Signal Design||2|
|PGA SD ADC and FFT resonant frequency of the measured signal by piezo sensor|
|Best approach to amplify piezo (self-generated) A/C signal at the 1mVAC level|
|How to use an Analog Front End with Piezo for Ultrasound Signal Processing|
|convert piezo signal to midi|
|Piezo signal amplification circuit question|
by Robert Keim