| 摘要 |
PURPOSE:To control power supply securely regardless of the kind of a load by supplying a firing signal which continues for a firing time to a triac as a switching element. CONSTITUTION:Phase angle data corresponding to power control over the load 11 is computed by a CPU25 and the numeral corresponding to the data is set in a constant register 23. Then, the set numeral is preset in a down counter 24 initially. Namely, an FF19 is reset in the initialization state and a clock pulse from an NAND circuit 20 is led out to bring the down counter 24 under down count control. When the counted value of this counter 24 reaches ''0'', the FF19 is set to supply a base bias to a transistor 26, which turns on to supply the firing signal to the triac 14 by a signal from a photocoupler 15, thereby applying AC power having a selected phase angle to the load 11. |
