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I am trying to build a relatively 'simple' circuit with a piezo sensor that turns on an LED for ~10-20 seconds after it has been tapped.

In the off-state the circuit should use zero current to preserve battery life. I would also like to avoid any ICs. Just some simple capacitors/resistors/mosfets etc.

I have tried a few different latch circuits - which seem to work fine with a normal button but I am not able to get them to work with the piezo sensor.

What would be the best approach to this?

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  • \$\begingroup\$ Best is probably an MCU implementing a timer; some (MSP430 for example) can sleep at under 1 uA. Best within your constraints will take some design care to match that power consumption... \$\endgroup\$ – user_1818839 Nov 21 '20 at 16:45
  • \$\begingroup\$ Zero current doesn't exist so be realistic. \$\endgroup\$ – Andy aka Nov 21 '20 at 17:37
  • \$\begingroup\$ Please provide technical information for your piezo sensor. There may be an easy way to do this. \$\endgroup\$ – Dwayne Reid Nov 22 '20 at 1:04
  • \$\begingroup\$ It's a 20 mm piezo disc. amazon.com/15-Pieces-20mm-Piezo-Elements/dp/B00A9AMHTI \$\endgroup\$ – muckyu Nov 22 '20 at 12:24

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