Switching circuit for connecting an AC source to a load
US4258276A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 23, 1978 |
| Grant date | Mar 24, 1981 |
| Priority date | — |
| Expiry date | Jun 23, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/136
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
In the disclosed circuit, a bilateral breakdown switch such as a triac includes two terminals for connecting an AC source to a load. A variable input arrangement, such as one which includes an LED and a photoresistor, operates a control electrode on the switch to turn the switch on and off in response to an input signal. The switch is disabled when the momentary AC voltage exceeds a predetermined value. This is done by a sensor that senses voltage and a bilateral switching arrangement that responds to the sensor and turns off the switch in response to a voltage higher than a predetermined value. According to one embodiment, the bilateral switching arrangement is composed of two complementarily poled transistors connected in parallel with respective bases connected to the sensor. Series diodes provide unidirectionality for the transistors. Back-to-back parallel diodes connected to the control electrode compensate for the voltage drop caused by the series diodes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.