Prolonged peizo and taskled

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darkavenger

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Apr 6, 2013
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I have an odd issue. I've used my prolonged peizo switch with two taskled boards successfully. I hooked up my new bflex board, however I couldn't control the circuit with the switch. I tested both independently of each other, both seem to be functioning. I have confirmed with taskled, there have been no hardware or software changes since my last bflex, which worked without issue. Does anybody have any thoughts on the subject? Perhaps I'm testing them incorrectly?

The taskled board responds to simply shorting the control circuit.

The peizo will create voltage and current, and for a few seconds when held since it is prolonged.
 
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darkavenger

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I don't have either of those boards anymore. I wish I could try it. The first died when a light flooded, and the second was broken when it fell off my workbench and I didn't take notice til it was too late >_<

I just don't understand why the piezo would suddenly stop working. It has sat on a workbench for a month, nothing has changed. Then again, the board responds correctly to being shorted. So what gives?

Edit: Testing indicates that when the piezo(isolated) is pressed, it produces about 3-4mA, diminishing to about 1mA after a few seconds if held. When connected to the circuit, even if the circuit is disconnected from the power supply, the switch produces nothing. Could the circuit or the piezo somehow by shorting?
 
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betti154

betti154

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I've never seen this before. My guess is the board is damaged in some way, but that is a guess. Not much to go wrong with a piezo.
 
DIWdiver

DIWdiver

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A piezo element is not a current source. A better analogy is a capacitor that you can dump charge into by bending it.

The consequence of that difference is that if you try to measure current, your measurement technique will have a huge impact on the result. You are better off measuring voltage.

But if you are talking about the prolonged piezo switch, that's a different animal. It has some circuitry in it to change the piezo element's behavior into something more like a switch. It should be treated like a switch, in that it either has continuity, or not. In truth it has either a very high resistance (>100,000 ohms, possibly much more) or fairly low resistance (< 10 ohms, possibly much less).
 
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Deeperdiverdude

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Oct 22, 2011
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Hi
I recently modded a custom diver head with a taskled driver and schurter prolonged piezo switch.
I found that the emi from the taskled inductor was interfering with the piezo swich.
Changed it for a momentary version and it worked fine. Unfortunately you loose the option of short and long pressed to control the driver.
I passed on my findings to George st taskled at the time.
For what its worth the switch was only about 10mm from the driver in my build
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