This is same circuit as above with the addition of a photo resistor to trigger the flip flop instead of a push button. The bias resistor in series with photo resistor was chosen so that sufficient voltage is present at the base of the 2N3904 to supply current to the circuit in ambient lighting conditions. The circuit should toggle when the photo resistor is hit by a flashlight beam or other fast changing light source. Slow changes in light intensity will have no effect unless the light gets too bright to maintain sufficient bias for the 2N3904.
From : http://ourworld.compuserve.com/homepages/Bill_Bowden/
Automatic light switch
Light activated switch
Light Relay Switch
Lighting Senser
Light Relay Switch By BC547 & BC337
Vehicle Interior Lighting With Switch-Off Delay
AC lights dimmer with triac
12V 10A Dark Activated Switch by LM324
Automatic Lamp Control with Light Sensitive Switch
Simple Light Actuated Relay by Phototransistor
This entry was posted on Thursday, April 26th, 2007 at 6:39 am and is filed under Electronic Control, Lighting.
