Switching circuit for connecting an AC source to a load

Claim 1

An alternating current switch circuit, comprising a bilateral switch having a control terminal and output terminals, variable impedance means for producing a variable impedance, coupling means coupling said variable impedance means from one of the output terminals to the control terminal for applying the voltage of one of the output terminals to the control terminal so as to turn on the switch when the impedance of the impedance means is lower than a given value, input means coupled to the variable impedance means for varying the impedance to a given value to turn on the switch, voltage sensing means for sensing voltages, bilateral switching means for exhibiting a high impedance when turned off and a low impedance when turned on, said bilateral switching means connecting said impedance means to the other terminal and being connected to said voltage sensing means while said voltage sensing means is connected across the output terminals so that when the sensing means senses a value higher than a given value, said sensing means turns on said bilateral switching means and disables said bilateral switch, said bilateral switching means including parallel current paths, and complementarily poled transistors each in one of said paths, said transistors having bases connected to said sensing means, each of said paths including a diode in series with the transistor of said path and poled with the transistor of said path, said coupling means including a pair of inverse parallel diodes connecting said impedance means to said control terminal.