Design and implementation of remote switching circuit utilizing I.R laser

Abstract

The aim of this work is to design and implement a circuit that can be switched by infrared laser (IR) source. The function of IR laser is to carry the binary coded control signal to a receiver location at which the received signal can detected and processed. To achieve this goal a transmitter and receiver circuits have been designed and implemented. At the transmitter circuit, IR laser diode with output power of 10 mW and wavelength of 808nm has been modulated using binary code. A binary code uses two possible states, 0 or 1 to transmit an optical signal. Thus transmitted optical message using a binary code would consist of bits sequence of 0's and 1's s .Specifically 0s would be transmitted when the light source was turned off. The 1s would be transmitted when the light source was turned on. At the receiver circuit the original signal has been detected by photodetector, converted to voltage and amplified. Then this signal was applied to the clock input of asynchronous counter, that counts from 0 up to 255(00000000-11111111).The counter outputs were connected to EPROM inputs. The EPROM was programmed to operate such light emitting diode(LED) of the eight LEDs connected to its output terminals ,when a particular counts were received .According to this work, the designed and implemented circuit has been operated efficiently and a good performance was obtained, and the shapes resulted from experimental work are clear and have a good resolution .The key parameters of operation of these loads are the pulse width and pattern of the written program in the E-prom., so in this fashion each one of the eight LEDs has been operated for a predetermined length of time according to the received counts.