Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

S.O.S. - piezo/transistor switch question

Status
Not open for further replies.

Random

New Member
Hey ETO, I have kind of an urgent question. I'm trying to finish a drum controller for a drum simulation video game, and I'm stuck on the very last part - interfacing the piezo sensors on the drum pads with the buttons on the PlayStation controller, which are supposed to be triggered (simulate a button press) when the pad is hit. The buttons on the PlayStation controller are negative logic, so I'm basically trying to short a contact to GND based on the spike of the piezo. I was told (several times) that this should be easy to implement with just one transistor, but my circuit isn't behaving correctly at all for some reason. I'm having trouble finding any information that'd help me understand what the piezo is outputting, and how I should tie it into the transistor in order for it to behave how I need it to, so I thought I'd ask you all for a direct solution. (Please! pleasepleaseplease)

Right now I'm using a 2N3904. I have the center part of the piezo going to the transistor's base, the outer ring going to GND (on the PlayStation controller), the emitter going to GND, and the collector going to the button's input on the PS controller board. It gave me sporadic responses when I had the piezo running directly to the transistor/board via hookup wire, but when I interface it with the 3.5mm mono extension cord that the drum pads use, it gives me random/frequent triggers when it's not plugged into the pad, and no response at all when the pad's plugged in. I only need a simple solution to this, simply grounding the PS button when the piezo is struck - I believe the game itself recognizes how long a strike should take, and adjusts itself accordingly, so I don't have to extend the spike from the piezo.

Here's a [crude] picture:
**broken link removed**


Part of the problem, I believe, is that I don't know where the two contacts on the piezo should be connected to, if there's an external power source in the circuit. Could someone clarify this for me, please? Also, if there's anything that I'm interpreting incorrectly in this process, please let me know. Thank you!
 
A piezo is very high impedance so it should connect to your circuit with shielded audio cable.
The input of your transistor doesn't have a resistor to ground to turn it off and doesn't have a series base resistor to increase the input impedance.
Maybe a darlington transistor should be used since it has a very high input impedance. Add a resistor at its input to ground to turn it off and a series base resistor.

Google has many links to circuits for piezo drum pad circuits, most use very high input impedance opamps with FET inputs.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top