Need Help with a Slightly Different LED Flasher Circuit - Novice Here!

Thread Starter


Joined Nov 14, 2019
Shish! Man, I REALLY appreciate ALL of everyone's input. I NEVER would've thought this simple little blinky LED scene would turn out to be such a complicated problem to solve!

I've been thinking a little more about it, and I think I'd rather try to go with components that I wouldn't have to program, trying to keep components as simple as possible.

I've bought some small perfboards, still haven't pulled the trigger on which 555 to buy. Same with the MOSFET. I really need to populate a list of components, so I don't buy a bunch of parts I don't need!

Again, thanks to EVERYONE for all your help so far, I've clearly come to the right place for this!


Joined Aug 7, 2008
I tried to send a PM ,private message, to you just to see if it still works.
I would stay with C version of 555, like 7555 or TLC555CP. Output is rail to rail .

Thread Starter


Joined Nov 14, 2019
Hey folks, been awhile!

So, I'm slightly altering the plan, here.

I'd like to do this with "Flashing" LEDs, now, rather than having to deal with the TLC555CN and all that.

I'd like to backlight the triangular LEDs with some small SMD flashing LEDs, and I actually managed to get this working, sort of.

I used a small coin cell battery holder, and a 3V lithium cell, along with two "pre-wired" flashing LEDs from, but it didn't work for long. It could be the switch I used, I'm not sure.

The switch was just a loose component I already had, and it has 4 pins, and it's a small 3 position slide switch. I had it set up so that in the center position, everything was off, and left was the Green LED and right was the Red LED. Unfortunately, the more I turned it on and off, the longer it would take for the LEDs to reach full brightness, until it quit working altogether.

The thing is, I'd really rather it work so that there's maybe a separate power switch, which will turn on the Flashing Green LED, then I can use ANOTHER switch to "interrupt" (turn OFF) the Flashing Green and turn ON the Flashing Red LED. It doesn't matter to me whether this switch is Momentary, or a slide switch/DIP switch, whatever, as long as it's small enough to fit in the box.

Then when I flip the "interrupt" switch back, the Red LED should turn OFF, and the Green should resume its flashing.

Is this possible?

I tried this today, but don't believe I have the right switches to do it. The best I could get was for one of the LEDs to turn on with the "main power" switch, then when I press the "interrupt" switch, the other LED would come on as well, resulting in BOTH LEDs flashing at the same time. Close, but no cigar. I really need that first LED to STOP flashing when I press/activate the second switch.

Any help is GREATLY appreciated! Thanks everyone!


Joined Apr 11, 2010
I know you wanted to do this with 80s technology and are unfamiliar with coding. But someone here mentioned they could supply the code. And when re-reading this thread, I’ll go one step further. I’ll supply a pre-programmed ATTiny in an 8 pin chip (same size as a 555) and all you have to do is solder the switches and LEDs to a PCB.

Thread Starter


Joined Nov 14, 2019
That's a most generous offer!

The thing is, I've recently realized that flashing LEDs were actually around in the early 80s, for model train enthusiasts, so, I figure that's likely what the practical effects/prop dudes went with.

I'm not knowledgeable enough to draw my own schematic for the circuit, but I ordered a couple more different kinds of slide switches, and hopefully I'll figure this out.

Here's a video from a couple months back, when I had it working with the three position switch, before it died on me.


Joined Aug 12, 2014
Power SW NO, control SW SPDT, common to power SW out.
In case anyone needs help visualizing this, I think this image captures what you were describing. In this arrangement, since the SPDT switch guarantees that only one LED is ever active at a time, they can definitely share just one resistor (and of course it could be in the negative side or between the two switches - it doesn't have to be where it's shown in the image below.)

Thread Starter


Joined Nov 14, 2019
Lord have mercy, I FINALLY got it!

So sorry for my ignorance, folks, and thank you all SO much for your help. Using a 3V coin cell.

I'd STILL like to eventually figure out how to do this with the TLC555, I wish I could adjust the rate of each LED's flashing, but for now I'm happy with this.

Oh, and here it is using 3mm LEDs, but they flash WAY too slow. These are apparently 2Hz, and the folks I bought them from don't have anything in between 2Hz and 6Hz, which is a bummer. I'm thinking something like 2.6-3Hz would be ideal.