Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

led dimmer circuit by using photocell...help me

Status
Not open for further replies.

tmmizwan

New Member
I have a circuit which can make led dimming by using 555 ic. In this circuit potentiometer is used to control the dimming. But I want to make led bulb dim depend on ambient brightness. So how can I connect the photo sensor like LDR to this circuit in order to make the led dim based on surrounding brightness.. Here I attached my circuit. anyone who know about it, please help me......
 

Attachments

  • ne555-pwm-led-dimmer-circuit.gif
    ne555-pwm-led-dimmer-circuit.gif
    4.7 KB · Views: 1,152
simply replace the pot with an LDR .. you shall have to recalculate the values of the resister - capacitor network ..
 
You could do it like this real easy just try to match your ldr's
 

Attachments

  • ldr.PNG
    ldr.PNG
    4.2 KB · Views: 1,262
thanks to amitak and be08e.

i have tried this circuit by using ldr. the problem is the led on with high brightness even in presence of high brightness of ambient light. when in the dark the led is blinking. I want the led off in the presence of enough ambient light. and will bright gradually when the ambient brightness is gradually become dark..

the second question is.. can i replace the led with small bulb.
 
to invert the led golw style skip the npn transistor and connect led's from vcc to the output of 555 (calculate the sink current that the 555 should take and verify that it is within limits)
to use the bulb too you need to calculate the current needed by the bulb, a bulb working on dc can be directly connected if the current needed is wothin limits
for an ac bulb or a bulb with higher current i suggest an opto coupler
the input bias of the opto coupler can be sink or source to get the on/off condition of led required
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top