Synchronized Flashing of LEDs

Dallee has a flasher circuit.    This may work for what you need.

Do you want them to blink together or alternately?  In any case, there are tons of flasher circuits to do either way.

Thanks @VHubbard.

Hmmm, good question @gunrunnerjohn.  I had envisioned them blinking at the same time, but alternating is certainly something I'm going to think about.  I'm putting them into the tail lanterns of a 6517 caboose.  I could see that alternate blinking might be something approaching my version of realism on my railroad.  I was also going to put them into the taillights of the 68 executive inspection car, and for that they would be definitely flashing together.

I would think you should not use the built in flashing LEDs but change to LEDs wired from a single flashing circuit.

A small built up timer circuit with a 555 timer chip will work.  Google this and there are many schematics for this.

@texgeekboy posted:

My question is, how do I make 2 red flashing LEDs flash synchronously?

For a simple circuit on DC, use 1 blinking LED in series with a non-blinking LED, with the appropriate resistor.

Thanks @Dtrainmaster.  Your suggestion was the easiest for me to try, so I did.  Unfortunately I could not get the non-blinking LED to blink, it was constant while the blinking one did blink.  Well, it was basically constant, I could see it dim just a little bit when the blinking one blinked.

I also confirmed that the LEDs I got in the package have enough slop in timing so as to be clearly not synchronized when I connected two together.

I'm still waiting for parts for this project so I'll probably refer to the other posts for other ideas in the near future.

Thanks again.

@texgeekboy posted:

...

I also confirmed that the LEDs I got in the package have enough slop in timing so as to be clearly not synchronized when I connected two together.

What are the blinking LEDs you have?  What are its power requirements? Do you already have a power source or circuit that presumably is driven by track AC?

Another approach is to use 1 blinking LED and split the light output into 2 points of light using acrylic fiber or plastic rod. Some blinking LEDs are so darn bright that you need to tone down the brightness so plenty to spare and share.

@stan2004,

I connect the track power to rectifiers from Evans, which I then connect to edgelec 12v blinking red LEDs.  These work well with a single blinking LED.

I'm modifying a 6517 caboose, and it does have a plastic rod to take the light from the original incandescent bulb to the little nibs that go through a hole in the side of the car to the exterior lanterns.  I was thinking I could get the red blinking light to use that rod after I take most of the plastic frame out, remove the incandescent, and then put in the overhead warm white LED strip, along with GRJs LED lighting regulator to eliminate flicker.

@texgeekboy posted:

...

I connect the track power to rectifiers from Evans, which I then connect to edgelec 12v blinking red LEDs.  These work well with a single blinking LED.

...

So you have something like the following?

And this works (LED blinks as expected)?   It's just that the so-called rectifier says it is meant to drive a 3V LED whereas your blinking LED expects 12V.  But if so, then so be it.

@texgeekboy posted:

Thanks @Dtrainmaster.  Your suggestion was the easiest for me to try, so I did.  Unfortunately I could not get the non-blinking LED to blink, it was constant while the blinking one did blink.  Well, it was basically constant, I could see it dim just a little bit when the blinking one blinked....

To be clear, please confirm the non-blinking LED was placed in series (vs. in parallel) with the blinking LED?

BTW, does anyone know what an "18V resistor" is per the Evans description of their rectifier.

@texgeekboy posted:

...  I was thinking I could get the red blinking light to use that rod after I take most of the plastic frame out, remove the incandescent, and then put in the overhead warm white LED strip, along with GRJs LED lighting regulator to eliminate flicker.

Do you mean to hook up the above 12V blinking LED to GRJ's lighting regulator module?  In basic terms his module is in effect a constant brightness controller.  I think what you will find, and GRJ will chime in for sure, is when the red LED blinks ON, the white LED strip will dim...in effect keeping the overall brightness constant.  OTOH if I mis-read your post and you are using GRJ's module to strictly drive the LED strip...and separately powering the blinking LED (e.g., with the Evans rectifier)...then ignore my ramblings.

@stan2004,

I have exactly those 2 products and the LEDs blink quite nicely.  I have a blinker installed on my 41 switcher and a CP Fire Fighter car.  As long as I don't think it'll kill me or cost me a lot of money, I connect stuff and worry about the ramifications later.

I did connect the lights in series.  I had done that on a previous project mistakenly and had to take it out and redo it in parallel.

Sorry, the lighting regulator will be for the LED light strip in the ceiling only, I will have a separate circuit for the blinking LED.  I hope to be able to position the single blinking LED in front of the rod to light up both sides.  It'll be a couple of weeks before I can get to that project though.

Here's a simple 555 circuit to blink either one LED or alternatively blink two LED's.

Adjustable Flashing/Blinking LED Using 555

Evan Design has what you are looking for. Look at the options for what you want the led's to do, choose your power ac/dc, or both, track power or battery. Inexpensive and it comes prewired wired in a harness and easily tucked into a car. I did alternating flashing lights on the rear of my caboose, looks sharp. I tried looking for a video but can't find one at the moment.

@Dan Kenny,

Yes, found them.  I'll be ordering them.  For all the others, thank you very much, but I'm a big believer in 'buy, don't build'.

@gunrunnerjohn posted:

Here's a simple 555 circuit to blink either one LED or alternatively blink two LED's.

Adjustable Flashing/Blinking LED Using 555

John did you look at the schematic ?   Guy has 5 pins on one side of the chip.   Here is the actual pinout.    j

@JohnActon posted:

John did you look at the schematic ?   Guy has 5 pins on one side of the chip.   Here is the actual pinout.    j

The pin numbers are correct, it's common for schematic representations of parts not to have the pin layouts exactly like the physical part.  When I call up a 555 chip in DipTrace schematic capture, I get this:

Clearly, that's not how the pins are arranged on the chip.  A vast majority of the IC's are this way in schematic capture applications.

The part I wondered about on the dual flasher is the polarity of the LED's.  How can LED2 be correct, the cathode is clearly facing the most positive part of the circuit.   I suspect that part should be reversed for proper operation.

@gunrunnerjohn posted:

The pin numbers are correct, it's common for schematic representations of parts not to have the pin layouts exactly like the physical part.  When I call up a 555 chip in DipTrace schematic capture, I get this:

Clearly, that's not how the pins are arranged on the chip.  A vast majority of the IC's are this way in schematic capture applications.

The part I wondered about on the dual flasher is the polarity of the LED's.  How can LED2 be correct, the cathode is clearly facing the most positive part of the circuit.   I suspect that part should be reversed for proper operation.

I am just wondering if anyone built this circuit to see if it works, I've built a couple that were posted on line only to find they don't work.

Ray

@Rayin"S",

I'm not sure what you're looking for, but this product from Evans Designs is exactly what I wanted when I started this thread.  If you choose the 7/19 volt AC/DC option, you'll get something that you can directly connect to track power.  I got mine yesterday, they work well, and I'm very happy.  I had some communications for Evans about asynchronous flashing as well, and their offering wasn't exactly what I wanted.  However, they did entertain the idea of modifications to their product to suit my needs (it was a simpler design actually).

@texgeekboy posted:

@Rayin"S",

I'm not sure what you're looking for, but this product from Evans Designs is exactly what I wanted when I started this thread.  If you choose the 7/19 volt AC/DC option, you'll get something that you can directly connect to track power.  I got mine yesterday, they work well, and I'm very happy.  I had some communications for Evans about asynchronous flashing as well, and their offering wasn't exactly what I wanted.  However, they did entertain the idea of modifications to their product to suit my needs (it was a simpler design actually).

I am looking for the alternating flashing LED circuit, I would like to be able to adjust the flash rate for different applications. The circuit I quoted above is for an alternating flashing LEDs. The adjustable flash rate is important for me, I have purchased many items from Evans and am happy with what I have but, now seeking something a little different.

Ray

@Rayin"S" posted:

I am just wondering if anyone built this circuit to see if it works, I've built a couple that were posted on line only to find they don't work.

Ray

Well, I can answer my question, I built this circuit using components close to the recommended specs. This was put together on a powered breadboard, I did reverse the one LED as John recommended and it works. I ordered parts to build several of these, thank you for posting this circuit.

Ray

Glad it worked, I knew that LED had to be wrong, but it was close.

I always look for your input on electrical matters.

Ray

@gunrunnerjohn posted:

Glad it worked, I knew that LED had to be wrong, but it was close.

You can get 5 alternating flasher module kits for $8.85 shipped from China (eBay item number:165117958891)

But you would need to adjust values of resistors and/or capacitors to change the rate.

For those who don't want to take the time to assemble a board, for $8.99 plus $2 shipping from California you can get 2 adjustable rate alternating flasher units (eBay item number:392900420800)

Bob

I finally finished my 6517 caboose with the synchronized flashing red lights.  I have a short video at the end for proof!  The hardest part was masking the flash from showing inside the caboose.  I took out the big clear plastic lens, put in thin sheets of plastic for the windows, added some overhead LEDs, and then put in some little people.

I used the Evans design flashing lights, but a word of caution.  They shrink wrap the connection, but the wires are not securely in that wrap (the wrap has to big enough to cover the electronics, and the wire is much smaller).  I've had wires come loose in 3 units.  I did mention it to Evans, and they did replace it even though I said it was my fault.  When the last one happened, I started adding shrink tubing to the wire connections to make them more secure.  It makes the whole thing more rigid, but it hasn't come apart.