Design and construction of a laser switch based electrical control circuit

摘要

To facilitate people with disabilities and those who are old, a novel laser switch based electrical control circuit is proposed. The circuit operates on 230V, 50Hz A.C. and can be operated at large distances of up to 10m. The laser switch is realized by using a diode laser that emits radiations in the visible region of light and a phototransistor as a detector. The electrical control is achieved by using a power EMOSFET to perform switching “on” and “off” operations. To prevent accidental switching operations a minimum contact time of 2.79 seconds is ensured using an incident time analyzer. The electronic circuit is tested for different laser wavelengths with a constant power output of 1mW. The device is also tested for different light ambiences. Test results show that lasers of wavelengths ranging from 652nm to 750 nm can be used for the desired switch operations.