This mini-VOX - voice operated relay - is based on a circuit published in Silicon Chip, 9/1994, p31. We have improved it by putting an on-board Koa potentiometer in order to adjust the sensitivity. The idea behing a VOX is that instead of the user pressing a switch to activate a relay, the sound of the users voice itself activates the relay. This gives hands-free control over devices like tape recorders.ASSEMBLY Check of the Components against the Listing. Follow the overlay. Note that the microphone should be located on two wires (not supplied) some distance away (like 1ft to 2 ft) from the PCB. It should not be mounted on the PCB otherwise vibration from the relay could trigger it continuously. Note one component is located under the IC so the IC socket has to be used.