SHOWALL FUN PRANKS HIGH VOLTAGE LAZARUS-64 PHOTOGRAPHY SPY GADGETS VIDEO GAME
Figure 8 - My solderless breadboard is now spying on me!
Figure 8 - My solderless breadboard is now spying on me!

Besides having the polarity of your electret microphone reversed, there is not much else that can go wrong with this simple circuit besides a wiring error. If you hear your relay clicking in response from the sounds but your camera fails to respond, then you can try using a larger capacitor for C1 in order to lengthen the pulse time from the 74121 on-shot. A simple way to figure out the approximate time needed to have your camera respond is to manually drive the relays by shorting the base of the transistor to VCC to activate the relays. Most cameras should be fine with a 1 second switching, but you may have to experiment with your camera.



Figure 9 - The completed sound activation system on small circuit board
Figure 9 - The completed sound activation system on small circuit board

There are so few components and wires in this simple circuit, that it only takes a few minutes to move from the solderless breadboard onto a bit of perforated board as shown in Figure 9. The components are placed through the holes in the perf board and then a circuit board is formed on the underside using wires and solder. You could certainly include the relay driver board and the sound activation board on the same circuit board, but having the ability to mix and match various projects is nice as well.

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