light sensing blinking LED's

Thread Starter

godfather55v

Joined Jul 26, 2016
3
i'm trying to build a circuit that when it sense's light it will blink a pair of LED's alternately. I wouldn't have thought this to be a very hard project, but i've killed a couple days on it already. I'm building my little sister-in-law a jewelry box that when it opens it will play a song and blink the led's. If possible i'd like to have them shut off after a period of time. I don't have room for an arduino, so i was thinking there should be a way to do this w/ a 555 timer and ldr sensor. The ldr will detect when the lid opens and then start the blinking lights.

Any help will be greatly appreciated!
 

#12

Joined Nov 30, 2010
18,217
First the LDR circuit, then a 556 chip. One timer to blink and the other to tell it when to shut off...or you can just insist the box be closed to avoid wasting the battery.

Leseee...a feedback loop from the second timer to latch out the LDR circuit so it can't be activated until dark has happened, and light has happened again. Yeah, I can see how you complicated yourself into a corner. I did one like this about 30 years ago.
http://forum.allaboutcircuits.com/blog/night-detector.658/

See how messy it gets when you want to do that shut-off logic?
It was the right circuit for a commercial job, but a music box? I don't think so.

Better to just shut off after x number of seconds and do the logic with the lid switch.
 

hp1729

Joined Nov 23, 2015
2,304
i'm trying to build a circuit that when it sense's light it will blink a pair of LED's alternately. I wouldn't have thought this to be a very hard project, but i've killed a couple days on it already. I'm building my little sister-in-law a jewelry box that when it opens it will play a song and blink the led's. If possible i'd like to have them shut off after a period of time. I don't have room for an arduino, so i was thinking there should be a way to do this w/ a 555 timer and ldr sensor. The ldr will detect when the lid opens and then start the blinking lights.

Any help will be greatly appreciated!
You want the LEDs to blink for 10 seconds? LM555 set for 10 seconds and self blinking LEDs. They come in all colors, just about. Some blink at about 80 times per minute, some flicker randomly, some flicker in different colors. Source I use is Electronic Goldmine.
 
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