Sound Control Unit
Sound Control Unit, A1-1200.75, £23.90 This board was designed to show an interesting way of operating our Relay board. The unit is primed by pressing the white switch and when you clap your hands in front of the microphone a 4.5V step change in the output voltage occurs. This voltage is big enough to operate our Relay board. The three AA cells (supplied) are contained in a holder underneath the board.

With the Relay board it is easy to show a small current controlling a large current. Note that the large current can be AC or DC. The photograph below shows the relay controlling a 2A lamp.

A Bonus
If you remove the microphone and replace it with an IR sensor(provided) then the board can be operated using our IR light gate source or a TV remote. Switch your IR source repeatedly on and off when investigating the range of the source - don't just switch it on and then move back and forward.

Note that the long lead of the IR receiver must be towards the bottom of the board.