Audio Activated Switch
This device allows audio to activate an electronic switch. The circuit is essentially a one channel color organ (for those that remember what those are), but with a small twist. This unit has three channels that turn on whenever the preset volume level or greater is achieved. The volume level can be adjusted by you.
The three channels can each sink (switch on) up to 1 amp each at up to 50VDC. What the circuit essentially does is connect the negative lead of your device to ground whenever it is activated and breaks that connection whenever it is not activated. Each channel could be used for devices that require different voltage levels, for example, one channel could be used for a 5VDC light, another for a 12VDC motor, and the third for a 24VDC solenoid valve. You could also use this a seemingly random on off switch.
The unit has four terminals on the board that provide access to the plugged in power supply voltage, (whatever that is, 9VDC or 12VDC) depending on what you have powering the board. Each terminal can supply up to 300mA of current and can be ganged for devices needing more current (though you can't exceed what your supply is capable of). It also has four terminals of 5VDC to power devices and has the same 300mA limit for each terminal. Again, you can't exceed what the supply is capable of delivering. You can also power devices off of supplies that aren't powering the board, just your device.
This could be used to operate the solenoid on a "Cat in the Box" prop or for running the lights and motors in synch with sound for an electrocution chair prop.