Hello!
What would be the simplest solution to ruggedize the input pin of a microcontroller against damage with repeated voltages up to 150V AC?
The 150V AC carry allmost no current, they are the output of a piezo element.
This is the best i could come up with, it works. But id like to ask, if there is a simpler way to do this.
Current limit resistors on the input/output side to protect in case of a short circuit.
Diodes to protect against reverse voltage/feeding and rectification.
Then there is C1 and R1, they form a envelope detector for some smoothing, without them i had a bit of a problem with multiple triggering since i do not want to use software debounce on that single pin, and R1 serves as a pull down for the gate.
D2 is a zener to limit the voltage on the gate.
Then there are D3 and R4 wich are used for a internal, low voltage trigger input wich needs to be inverted.
I would like to have the option to connect either an external voltage source as a trigger, the piezo element or a simple switch.