UAA 170 economiser

It is well-known that, for mm1mum gen- eration of interference pulses, triacs should be triggered near the zero-crossing point of the mains waveform. There are a number of zero-voltage switch ICs in existence, but unfortunately these are expensive and often difficult to obtain. As these ICs need a number of external components in order to function, a discrete component version of the circuit need not take up much more space, and is certainly cheaper.