| 摘要 |
This disclosure relates to electronic switches in which touch elements, separate from each other, must be touched to actuate the electronic switch to operate a load. In a first embodiment, the electronic switch energizes a load when the operator brings his finger near or touches a first touch element, and the electronic circuit deenergizes the load when the operator's finger is removed from the first touch element. A second touch element latches the electronic switch on when the operator touches or brings his finger close to the second touch element. Unlatching is then accomplished by momentarily touching the first touch element. In a second embodiment, the circuit is of the "AND" type and the operator must touch two touch elements continuously to maintain the electronic switch on and the load energized. In a third embodiment, two touch elements must be touched simultaneously to initially energize the load and thereafter the operator need only maintain his touch on or near one of the touch elements to maintain the load energized. In all the embodiments, the electronic switch is of the solid state type and is packaged in a small size electronic module capable of being mounted within the handle or casing of tools or appliances such as a portable electric drill, a router, or a grinder. In each embodiment, two SCR's each controlled by its respective touch element, cooperate to trigger a triac on for full wave conduction, or for half wave conduction, if desired.
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