초록 ▼

A one shot firing circuit for electrically powered tools is described which includes a manually operable normally open trigger switch connected electrically in series with a solenoid coil and an AC power source for controlling the supply of electrical power to both the firing circuit and the solenoi

A one shot firing circuit for electrically powered tools is described which includes a manually operable normally open trigger switch connected electrically in series with a solenoid coil and an AC power source for controlling the supply of electrical power to both the firing circuit and the solenoid, such that when the trigger switch is open, the path of current flow to the solenoid coil is physically interrupted. The firing circuit also includes an SCR connected electrically in series with the trigger switch, the solenoid coil and the AC power source, for controlling the flow of current through the solenoid coil after the trigger switch has been closed. The firing circuit further includes a timing circuit connected to the gate of the SCR which is operable in response to the closing of the trigger switch to provide a predeterminable delay after the trigger switch is closed before enabling the SCR to conduct and permit a unidirectional current impulse to flow through the solenoid coil of sufficient magnitude to energize the solenoid. The timing circuit also operates to disable further unidirectional current impulses through the solenoid coil once the solenoid has been energized until a predeterminable delay after the trigger switch has opened.

대표청구항 ▼

A one shot firing circuit for a portable electrical power tool having an inductive load adapted to be connected electrically in series with a source of alternating current electrical power, comprising: manually operable normally open switch means, connected electrically in series with said inductive

A one shot firing circuit for a portable electrical power tool having an inductive load adapted to be connected electrically in series with a source of alternating current electrical power, comprising: manually operable normally open switch means, connected electrically in series with said inductive load and said source of alternating current electrical power, for controlling the supply of electrical power to both said firing circuit and said inductive load, such that when said normally open switch means is open the path of current flow to said inductive load is interrupted; controlled conduction means, connected electrically in series with said normally open switch means, said inductive load and said source of alternating current electrical power, for controlling the flow of current through said inductive load after said normally open switch means is closed; and timing circuit means, connected to said controlled conduction means and responsive to the closing of said normally open switch means, for providing a predeterminable delay after said normally open switch means is closed before enabling said controlled conduction means to conduct and permit a unidirectional current impulse to flow through said inductive load sufficient to energize said inductive load.