So I'm working on a top secret (at the moment) project, and I need to figure out an LED circuit that will make an LED blink off for a half second or so every 5 or so seconds. I've found flashing circuits, and I've found flashing circuits that increase the off time, make the LED flash at a set amount of time, but I haven't found the opposite, and I'm not good enough at this stuff to figure it out. HELP!!!
Is this for an automotive circuit? If so, just check out alarm LEDs - it's what they do.
Google up 555 timer circuits.
Not my area of expertise, but I just grabbed an Android phone app on a friend's recommendation called ElectroDroid which has calculators to help with both LED circuits and 555 circuits (among a bunch of other stuff). Haven't really played with it, but if it works as well as it looks, and you have an android phone, it might give you all you need...
Dr. Hess wrote: Google up 555 timer circuits.
+1, add a binary counter to extend the interval range for off/on. If you try to go too long with a 555 and a filter network it will get wonky on you.
Read this:
http://www.reuk.co.uk/Repeat-Timer-Circuit.htm
555
If you're using a circuit that can increase the off time, just reverse the LED and connect to the LED to the other polarity (ie: have the chip source voltage instead of sink it, or vice-versa).
But,
++1 on 555.
+++1 on 555
Make has a lot about 555 timers on their website.
I pretty much want to simulate blinking eyes, with the LED being on when when the eyes would be open. I've read up a bit on 555 timers, but most of the circuits I found were doing the opposite of what I want, and I don't really understand what all the components are doing well enough to change that. That being said, I think I found a diagram that will do what I want it to.
even if it doesn't make perfect sense right now, use the 555. anything else will just be a bigger headache in the end. 555 is the tool you need for this job!
If you already have a flashing circuit figured out that will turn the LED on for 1/2 second, then off for 5 seconds, just use that circuit to run a single pole double throw (SPDT) relay. Then, power the LED from the normally closed contact of the relay - it will reverse the logic of the flashing circuit, so the LED is on for 5 seconds and then off for 1/2 second.
Alternately, you can get programmable timing relays from Allen-Bradley or other companies that will do what you want to do, but you'll have to spend 40 or 50 bucks (some examples are Allen-Bradley 700-FE, 700-FS, 700-HNC or 700-HR.) Also, these programmable relays generally run on 120vac or 24vdc, so if you're using 12vdc like in a car they probably aren't what you want.
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