The camera I’m using for this example is a Samsung NX1000 Smart Camera. The camera is activated when the external trigger contacts are shorted to ground; so the circuit we’re making shorts a signal to ground whenever there is a “loud” noise.
•SimpleCircuit Microphone Board
•SimpleCircuit N-Channel MOSFET
All Simple Circuits can be found on our Kickstarter Page
Step 1: The Schematics
The first schematic is the Microphone circuit (Single Supply).
Connect the output of the microphone to the voltage comparator circuit (Second Schematic)
Connect the output of the Comparator to the N-CH MOSFET
Connect the Drain of the N-CH MOSFET to the camera trigger
The third Schematic is the entire design redrawn with Simple Circuits!
5V for VCC works well. You could go as high as 12V or as low as 3.3V if you need to.
DON'T FORGET GROUND!
Step 2: Time to Test
Position the microphone so it’s near the sound source. Adjust the turn pot on the comparator at the same time you’re producing the trigger noise to set your threshold value. Connect your camera when your happy with the sound sensitivity. (*Remember: The LED should be normally OFF during silence and momentarily ON when the sound threshold is breached.) If you want to make slight adjustments to the time delay (i.e how long the circuit waits after the trigger noise) try moving the microphone further back. You will be surprised at your results (we were). If you want longer delays, you can insert the frequency generator SimpleCircuit between the comparator and MOSFET. If someone needs help with this please post a comment below and we’ll help you get set up.