Perfect Electronics has recently introduced an educational kit, a cordless, mains operated intercom. It has the following features: * One set of intercom consists of two units. * Each unit operates on mains, AC 230 volts. * Phase lock loop [PLL] technique is used in this intercom. * Carrier frequency used is 140 kHZ and audio signal is FM-modulated. * There is no static noise in the receiver when there is no signal. * The range is 300-500 metres along the main line. The company manufacturestechnology transfer, which includes circuit diagram, details of PCB and films of PCB.
