I'd like as an end state of my project for sound to activate a relay and then either
- a) the relay to stay on for a limited amount of time (~15 seconds) or
- b) ideally - the relay to be triggered off with another sound
I understand that either of these can be achieved with a 555 timer chip, I am loathe to use option a) because I hear that they can be fairly inaccurate when it comes to lower time limits (e.g. 15 seconds)
Here is what I have currently
Microphone can be found here https://www.sparkfun.com/products/9964
The LED flickers pleasantly in time to music. This seems problematic for a bistable switch - because I can imagine that the sound activation (ideally a shout, or a knock) will have to many pauses and lilts for it to trigger the bistable switch only once - I think this is a phenomena called bounce.
Is this circuit dangerous? How could it be improved? How do I fulfil option a) or b)? Why if I put a capcitator (I've tried a range of capacitances and ceramic and electrolytic types) before the LED and after the resistor the LED will no longer turn on.