JakeElwood

Sounds good, I'll give it a try. Once the pulse width is right, the only other change I'll have to make is to put two LEDs in series (and change the resistor as needed).

Knock it off. I'm going from a $50 kids' starter kit to reading this stuff, it takes time. It looks like the 4HC14 has six identical oscillators (schmitt triggers) any one of which can be wired like in your schematic. It's still not clear how these pins relate to the pins on a 555 (threshold, trigger, reset etc.) but I guess it doesn't matter as long as it works. I've thought about using flashing LEDs but I don't think that will give the right pulse waveform. Making strobes seems to be the default for many blinker circuits - making a light blink briefly OFF instead of ON seems less common. Still pretty simple though, I'll get it. Thanks again.

Thanks - I'll give it a try. I'm sure I can find the pinouts for the 4HC14 - I just don't know how to read the schematic yet (which side of the triangle figure corresponds to which pin). Input, output, power and ground make sense from the figure but then there's triggers, thresholds, reset etc. I assume that varying the pulse width is just a matter of changing out resistors and capacitors. As far as the LED pair goes my power supply is 9V with a voltage regulator that brings it to 4.5V so I'd need to mess with that to get 6V. Time for more reading, more theory. Anyway thanks again!

and which pins on the 74HC14 are you using in that diagram? maybe this thread is relevant? http://www.electro-tech-online.com/electronic-projects-design-ideas-reviews/33216-how-do-i-connect-74hc14.html

Hero - Right, that was your circuit I built. I meant 120 bpm, which would be 0.5 Hz, my mistake. It looks like it was working correctly, even with the 220 resistor. I was changing out all the components to experiment, I hope I didn't damage the 556. I was also careful to match the 556 pin numbers with the 555 pin numbers in your schematic. This is to make a blinker, not a fader, right? The end result should have the LED pair blinking on and off with a square pulse, about 95% on and 5% off (or less), at 1-3 second intervals (variable intervals is the next project). I can run six independent oscillators on a 74HC14 chip? Is there a buying guide for ICs and PICs? There seem to be several that I could use and I'm not clear on which I should get. I'm planning on getting a few extra 555 or 556 chips since they seem pretty useful.

I tried the circuit and it gave a fade-in pulse at about 120 Hz, but I was using a 220 cap instead of the 330 in your diagram so maybe that was part of the problem. No worries, I have about four other schematics I've found online that I can try so I'm sure I can sort it out (except for the random blink intervals but that can wait).

The next step is to get the blinks to occur at random or semi-random intervals, but first things first.

Thanks Hero999, I appreciate it! One circuit for each pair of eyes should do it.

This guy did it with even fewer components - if the on and off parts of the cycle were reversed it would be perfect: http://www.cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html

Ken - Thanks for the express PCB link, I'll see what I can draw up. Gogo - I have all those parts plus the battery clip and breadboard so I'm good to go, except that I have almost no clue as to how those parts would go together. I do know that a pair of LEDs can be wired in series with the appropriate resistor, transistors can be used as switches, and capacitors will affect the timing. Looks like it's time for some experimentation, but I'm told that I can fry transistors (and LEDs) if I hook them up wrong. Good thing they're cheap.

Well you've talked me out of the house current idea since the brightness at 5v is fine for this job. I have a simple circuit (from a starter kit) using a 556 chip that blinks an LED and the timing can be tweaked by changing a capacitor. Now I need to blink 2 LEDs at once (wire in parallel each with its own resistor?), get it to blink off instead of on (transistor NOT gate?), and then get several pairs going at different rates. Will each pair require its own chip? I'll post a schematic if I can find a nice online utility for drawing one up. Jon

Great, thanks for the link! It would be my first soldering project but at $5 I think I can chance it. My application is unusual since my "pulse" time is actually the longest part of the cycle. With this board the maximum pulse is 5 seconds and the minimum pause is 2.5 seconds, which is too long for a blink, so I'll probably be replacing a pot or two. The other option is to use the unit as-is and add a component to reverse the pulses and pauses, if such a component exists.

I guess the control circuit could be at 5V or whatever PICs run with, and a relay on that circuit would control the house current? The goal would be to have one controller (or several if necessary) creating the individual blinking patterns on a separate circuit with house current (either attached lamps or separate outlets for each flasher circuit). Or the whole thing could be 115V but that might make it tricker to work with and test. I've heard of high-intensity LEDs and they might be enough, but I'd like the option of flashing something brighter if the LEDs (hacked Christmas light chains etc.) don't do the trick.

Thanks - I see a few flashers out there but not quite what I'm looking for. I need a flasher that will work with 115 volts, not just a couple of LEDs on a PCB. I assume there's some component that will allow these flasher circuits to do this so it's just a matter of research.

Hi, I have a small Halloween project. The final goal is to have several pairs of LEDs (cut from a Christmas light chain) and have each pair wired to its own flasher circuit. The intervals wouldn't have to be random, but the timing of each flashing pair should be different. A simple timer should do the trick. One pair might have 1.5 seconds on, 200ms off, and the other pairs would have slightly different timing. You then hide the pairs of LEDs in the bushes and voila, blinking eyes. I'm only familiar with basic electronic components so until I get beyond the "beginner electronics hobbyist" phase a lot of the terminology is going over my head. Can I fake this by wiring fluorescent starters into each circuit or using those flasher buttons that you put in a light socket? Thanks, Jon