| 摘要 |
PURPOSE:To limit electric power to a constant value without any influence of ambient temperature by detecting the rate of the supply electric power to system and limiting the electric power with regard to time. CONSTITUTION:For example, specific electric power is supplied to a load resistance 11 from a transmformer 7 through a rectifying circuit 10. A voltage proportional to the product of a current flowing and a voltage applied to said load resistance 11 is compared with a reference voltage 12 by a detecting circuit 14 to detect whether electric power more than preset electric power is supplied or not. Its output signal is inputted to a timer circuit 17 and a set and reset circuit 16 through an averaging circuit 15 and a set signal is outputted by the set and reset circuit 16 to the timer circuit 17 when the supply electric power exceeds the set electric power to perform counting operation. Then when the electric power is supplied for longer than a set time, the timer circuit 17 outputs a signal to a stop signal generating circuit 2 to protect the electric power. |
