So you momentarily (as in quickly) just press the button and it works as advertised? Meaning you do not need to hold the button for the duration? I asked that earlier. I also asked if momentarily pressing a button resulted in terminating to ground or better put does one side of the button go to ground? I also asked that? If you have even a basic DMM (multi-meter) you can check and see if one side of each button terminal is ground, terminal to terminal should read a few milli-ohm. Also measure across each pair of button terminals for a voltage when the terminals are open.

If all it takes is a momentary tap on a button then this likely can be made to work very simply if the buttons all have one side common to ground.

Ron

 

You can change what the button does using a cfg file that's stored in the same folder that the samples are stored in, but the default action is you momentarily press the button and the sample plays all the way through. You don't need to hold the button and the sample will pay all the way through. If you hit the button while the sample is playing it will cause the sample to restart. Again, you can change this setting in the cfg file, but these are the default actions and this is exactly what I want to happen when I strike the trigger pad.

The buttons each have 2 wires. One wire goes to ground, the other wire goes to the corresponding port to trigger the sample.

If I could figure out a way to reliably trigger the buttons by striking a pad mounted above them I'd be golden, however I've tried many ways and can't make it happen which is why I'm back to trying to make the piezo's work.

Piezo's I think are a better solution for a trigger system that will be struck with a drumstick anyway.

I'll check the peizo's on a multi-meter when I go back to the office tomorrow.

 

OK, I think there are a few simple options. They will involve just a simple single transistor. I'll toss something out a little later. The transistor will be a 2N3904 general purpose NPN transistor but any basic NPN switching transistor will work. We may add a common diode like a 1N914 or similar, pretty generic stuff.

Thinking further maybe a MOSFET like a 2N7000 would be a much better choice over a 2N3904. Yeah, it would be. About a buck if that.

Ron

 

Sounds good to me! Would love to get this thing working. Looking forward to hearing more about this idea.

 

This is the revised drawing using 555's. Cost in parts about $ 2.00 / section. As shown all sections would most likely trigger on power up but easily fixed common to all.
How large would striking pads be ?
Sensitivity of piezo is improved if modified like a seismometer, mounted just by outer rim with a weight about the size of a LR41 button cell cemented to center of white aria. That is what I used for tests except that it is mounted on plastic disc with an alligator clip for attachment to target.

 

You may refer to the thread below:
Piezo Trigger Switch
https://forum.allaboutcircuits.com/threads/piezo-trigger-switch.98418/

 

My first choice would be using a one shot as Bernard has posted. However keeping in mind that you are not quite and electronics type here is something you can try:



While I have some piezo sensors lying here I don't have a 2N7000 MOSFET to actually try it. My piezo with a good tap give me about a 10 volt peak to peak. The D1 diode should clip the neg peaks and what remains hopefully will trigger the 2N7000 MOSFET. Again this is untried but it is simple.

Ron

 

I'm going to bring this schematic to a buddy at work who might be able to help translate it into something I can understand and build. I'm sure it's a straightforward circuit, but I wouldn't know where to start and I don't want to ask you to spend your time explaining schematics to a beginner.

 

If the MP3 will trigger from a series if 20 u sec. pulses then the MPSA14 or @Reloadron's circuit should work. If the MP3 SW inputs have bounce protection then there might be problems with short pulses ? If a piezo is rectified then a resistor across the piezo is recommended to discharge its capacity, 100k - 1M.

 

My first choice would be using a one shot as Bernard has posted. However keeping in mind that you are not quite and electronics type here is something you can try:

View attachment 217482

Reload Ron, this diagram is labeled with 'button terminal' but you're referring the leads from the peizo, right?

 

Yes, I reflect two button terminals and have the MOSFET source (-) and drain (+) across the button. When the MOSFET gates On with a signal from the piezo it should simulate a button closure.

Ron

 

Good deal, thanks man. Headed to my local electronics shop tomorrow to see if they can help me give it a shot.

 

Here is another piezo trigger concept that I cooked up a long time ago.

This can be made very sensitive, and always triggers on the first leading edge of the signal.
This was to be sure that the response time is consistent, regardless of the polarity of the trigger pulse.

 

The piezoelectric transducer that I have on hand produces about 5-10V, 50-100μs pulses on tapping.
You don't need any amplification, just inversion using any NPN transistor such as 2N3904.

Connect transducer between base and emitter of NPN transistor.
Connect collector of transistor to switch input.
Connect emitter to circuit GND.

The polarity of the transducer is important. You need positive signal to the base. Try reversing the connections if it doesn't work.

 

The piezoelectric transducer that I have on hand produces about 5-10V, 50-100μs pulses on tapping.
You don't need any amplification, just inversion using any NPN transistor such as 2N3904.

Connect transducer between base and emitter of NPN transistor.
Connect collector of transistor to switch input.
Connect emitter to circuit GND.

The polarity of the transducer is important. You need positive signal to the base. Try reversing the connections if it doesn't work.

The impedance is very high, not going to get much current to flow to drive the transistor's base.

 

The impedance is very high, not going to get much current to flow to drive the transistor's base.

No problem. Then use the circuit posted by @Reloadron in post #27.
I have tested this with 2N3904 and the post #27 circuit with 2N7000 and they both work. It works just as well without R1.