Beginner here, seeking advice on understanding the very different schematics I'm finding about wiring a piezo as a vibration sensor.
In the Arduino program, there's a 'Knock' program (Examples 06->Sensors) that instructs wiring the positive terminal of the piezo to A0 and the negative through a 1M Ohm resistor to ground, like in the Tutorial book. That's in series, yes?
But other projects instruct wiring the resistor in between both leads of the piezo (in parallel, yes?), like at this site
While others suggest adding diodes as well (and 470k Ohm resistor instead?):
I think I understand that last schematic, but I don't know how to gauge its value compared to the other designs, and I'm left with these questions:
- Is it better here to use the 1M Ohm resistor in series (to ground) or parallel, and why?
- What's the function of the diodes, and why use both Zener and Shottky?
- Are the diodes an improvement here or unnecessary? All 3 or just 2?
In case it helps, here's the big picture: I'm aiming to make a target sensor that can tell when hit by a nerf dart, and using the approach discussed in this Forum thread:
All this is new to me, but I think I can work out the code if I have a sensible wiring plan. Does that last one look good? Something else?