Dark room hand touch control circuit

Published:2011/5/17 2:36:00 Author:Nicole | Keyword: dark room, hand touch | From:SeekIC

Two helical or mesh electrodes with 1.58mm spacing are fixed in the bulb table or any other convenient places in dark room, when the hand touches the electrode one time, the 180W bulb turns on, if the hand touches it again, the bulb will turn off. The AC power is changed into DC power by rectifier diode GE504A, it is fed to Q1, Q2. When the hand touches mesh electrode, the Q1 base circuit is turned on, then Q1 is conduction, Q2 turns off, in the positive half cycle of AC power, SCR turns on, 180W bulb is lightened, L1 6W small bulb is lightened too, L1 illuminates Q1, it keeps Q1 conductive, Q2 is turned off, although the hand has been left the electrode, the bulb is still shining. If your hand touches mesh electrode again, then Q1 base turns on, the carrier which is produced by L1 shining on Q1 will be released from R6, R7, then Q1 is cut off, Q2 is turned on, SCR is not turned on, 180W and 6W bulbs are all died out.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Control_Circuit/Dark_room_hand_touch_control_circuit.html

Print this Page | Comments | Reading(3)