Switching circuit for ohmic or inductive load - has diac between triac and rectifier bridge controlled by diode with switch

摘要

The switching circuit for an ohmic or inductive load (2) includes a triac (1) in series with the load, and connected to a diac (3) supplying firing pulses. The diac is controlled by a parallel capacitor (4) and a variable resistance (5) connecting it to a rectifying bridge with four diodes (6 to 9). In parallel with the diac and the capacitor is a diode (16) with a switch in series which can be used to disconnect it. In an alternative circuit, the diode is between the diac and the resistance, and the switch in parallel with the diode.