Minimal light intensity light control switch circuit

Published:2011/5/23 20:47:00 Author:John | Keyword: light control switch | From:SeekIC

In the situation with minimal light intensity, it is not appropriate to use photosensitive photodiode resistor or general photodiode. It is advised to use dedicated photodiode BPX63 with minimal cut-off current. In the circuit, the light irradiates on diode D1 continuously. If switches S1 and S2 both close, the photocurrent results in short circuit. At this time, FET T1 and T2 and the resistors R1 and R2 constitute the source emitter follower. When the switch S2 closes, the output of operational amplifier is connected to the input of the anti-body of same phase through the field-effect transistor. If the switches S1 and S2 both open, the strong negative feedback circuit cuts off. But the operating point of field-effect transistor T2 changes.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Amplifier_Circuit/Minimal_light_intensity_light_control_switch_circuit.html

Print this Page | Comments | Reading(3)