Dimmer, light sensitive, How to do?

Thread Starter

Arne Franklin

Joined Jan 31, 2005
I want to bulid a dimmer that controls the 230 volts outdoor lights so when it is bright light outside, the outdoor ligts are bright and when it is dark outside, the outdoor lights are dimmed. The dimmer should not react too fast, so the lamps are twinkling when cars are passing withthe lamps on.

Anyone hwo know about digrams for such a unit?


Joined Jan 24, 2005
this may sound a lil wierd but y do u want the lights bright in the daylight? did u mean it the other way around? ill c if i can find a schematic for 1...l8er



Joined Jan 22, 2004

i guess you already have seen the schem for a light dimmer that's using an LDR to control the light. the light goes into on state when its dark and goes off when its bright. in that circuit there's a voltage divider circuit. it has a resistor in series with the LDR and the base of a driver transistor is connected to the junction of this two resistance.

just interchange the position of the resistor and the LDR. the result, when theres light outside the lamp turns on and when its dark it turns off. :)


Joined Jan 22, 2004
hi arne

there are lots in the net, there are those operated in AC/DC variations, AC operated with the use of triacs or triacs driven by diacs. just do a google search for AC Lamp Dimmer. what you will find are dark sensors, the light will turn on when its dark and turn off when theres light. :) what you want is jsut the reverse, hence my suggestion. :)