Zero trigger integrated circuit temperature control circuit 2

It is a current zero trigger circuit using KJ008 or KC08 integrated circuit
to achieve automatic temperature control.
    In the figure, the synchronization voltage is taken from the second electrode of the triac V. When the load current is zero, V is off. In this circuit
, when the furnace temperature is lower than the set value, as long as the potential of pin 2 is lower than the potential of pin 4, a pulse can be output when the load current crosses zero
, triggering the bidirectional thyristor to turn on; otherwise, the bidirectional thyristor will turn off. , thereby achieving the purpose of AC voltage regulation.