Hi!
I would like to build a small blinking circuit with 2 leds as eyes, I thought about using a 555 with ON time around 6 seconds and off time around 0.2 seconds (not fade) I also thought about using a 20uf capacitor for C1.
Could anyone tell me what values I should use for R1 & R2 (or C1)
Another Thought ....
Would it be easy to insert a LDR somewhere so that it would only work at night?
Thanks for any help you can give
Regards,
Heedthebaw

 

Lots of 555 info and timing calculators here:

http://home.cogeco.ca/~rpaisley4/LM555.html

Ken

 

You want more? Have some

http://pcbheaven.com/handbook/calculus/index.php?calc=555monostable
http://pcbheaven.com/handbook/calculus/index.php?calc=555astable

 

See the attached; that ought to do it for you.

 

Thanks for the quick replies!
I'll check out the links and thanks SgtWookie for the values, It's exactly what I want.

Regards,
Heedthebaw

 

I have a similar function for Halloween, but I have built a bunch of the circuits with a duty cycle of 30 to 50% and a wide variation of frequencies, all designed to chain off each other so I can use one battery per bush. I deliberately mixed a pile of resistors so they would be semi random. I put them in my bushes around the house, the effect is their full of glowing red eyes. I just love scaring little kids, but I give out good candy.

 

Hi Bill, I want to do something similar, I have a few Gargoyles around the garden and I would like to add the red eyes to them, blinking every so often. As you said, I could put a couple in the bushes for added effect. These would be permanent, so I want to use 12v transformer. I want the yobs to feel that they are being watched and maybe move down the road a bit. (every little bit helps).
I don't know much about electronics, but I can pick up bits and pieces from the links kammenos & KMoffett gave me.
Thanks for replying to my post,
Regards,
Heedthebaw

 

I think a fake camera might give them more to pause. Like I said, I aim for mostly off, then fill em up so their are many eyes all over. You might have trouble cutting the bushes back if their filled with wires (think Christmas tree).

 

An ordinary 555 draws current even when it is not doing anything. The battery will be drained.

You need a more modern circuit.

 

Hi Guys, thanks to everyone who replied, my "eyes" are up and running inside my gargoyle, and looks good. I'm going to put another pair in another gargoyle, but roughly double the ON time and half the OFF time. I'll just change R1 & R2 to suit.
Regards,
Heedthebaw

 

The software I used to calculate your R1/R2/C1 values can be downloaded here:
http://www.schematica.com/555_Timer_design/555_Timer_PRO.htm
You can use it indefinitely in the "lite" or "pro demo" mode for no cost.