Check out this thread. . .

Here is a recent thread talking about FRED. . .

https://forum.mrhmag.com/post/adding-a-f-r-e-d-to-a-railcar-12185762

Take care, 

check out the last 3 pages of

check out the last 3 pages of the link brothaslide posted above and page 9 is the link to what we came up with. I ordered parts to assemble one to see if I could make a portable unit with a coin battery power supply and the order will arrive sometime next week.

Dan

FRED

Thanks for the answers.
Ill take a look on the pages.

Regards
Hans Ole

FRED circuit

Here is a really simple FRED based on the now discontinued LM3909 flasher IC.  The circuit needs only one other component to work, an electrolytic capacitor that functions as the timing device.  Powered by a 1.5 V battery, just add a small red LED and it will flash for about a year on an average AAA cell battery.

Even though there are very few components in the circuit it still measures about 1/2" X 1/2" X 3/8" so it is too large to hide under a rail car.  It would have to be mounted inside a boxcar or hidden in a load.

I found a source for the LM3909 that is not too outrageously priced but these chips are harder to find and some on eBay are ridiculous.  I ordered a bulk amount to get a break on the price and make it worthwhile to ship overseas.

 Useful in any case where a flashing LED is desired.

Nice circuit Blue great to

Nice circuit Blue great to see you got one working. Since you like to experiment now you need to get away from the larger Caps and try using A {5V 25W 220uf micro chip capacitor} they are about 3/32" wide by 1/4" long and 1/16" thick they also come as small as half that size but I'm not sure they would work being you need electrolytic Caps.

Dan

Capacitors

Dan,

Yes, I finally got my shipment of IC's and it wasn't long before I had lights flashing.  The circuit is flashing away beside me right now.

I have experimented with the non-electrolytic caps I have on hand.  They cause the LED to light all the time but with a muted glow rather than full illumination.  Oddly enough, the circuit doesn't seem to care if the electrolytic cap is wired with correct polarity, which is what first made me think a ceramic or monolithic cap might work.  I need to find a smaller electrolytic cap.  It's that bulky 220uF electrolytic that makes for the large footprint.

Did you ever get the FRED circuit you ordered?  Are we going to hear more about that from you soon?

I just haven't had the spair

I just haven't had the spair time lately to order the parts let alone build the circuit.  I've been starting a bussiness with 2 friends and ever since the 8th of Janurary I have been working 22 hr days and been lucky to even get to sleep 4 hrs at a time. Also until tonight I've only had about a total of 1 hour since Jan 8th to even look at MRH or the forums.

Things are winding down and we are getting everything under control now so maybe in the next few weeks I'll be back on track so to speak and can get back to model Railroading and actually have spair time again.

I'm looking through my Electronic schimatics and papers that I have collected over the past 50 years and there is a tiny circuit that uses all micro chip componets to make a mini voltage interupt timer that will work like the Little flasher. I just need to find the paper it's drawn on.

Dan

FRED video

Ok, I have wanted to try out the video embedding so here goes.  Nothing exciting just a flashing light and some titles.

Hope this works.

Looks like it works better than mine!

 I tried to build a FRED unit a few years ago, and it was a spectacular failure. All it was made of was 1 stock flashing LED, 1 resistor for the LED, 1 9V. battery clip and battery, and 1 switch. It worked good, but then I tried to solder the switch in, and I tried it out, and wouldn't you know it?, the LED fried (both hypothetically, and really. It started to melt right before my eyes. ) That's how bad I am with electronics.

Then again, I was using the worst soldering iron ever (a Cold Heat iron I got on sale at some department store that specialises in clothing) Mabe I ought to try it again, with my regular, plug-in-to-the-wall soldering iron.

It works well...

CSX,

Yes it does work well, the only hurdle I still have to overcome is how to build a FRED package that is small enough to conceal under any piece of rolling stock and can be easily placed on any piece of rolling stock.

We thought we had the answer in a tiny circuit designed for Z-scale but it required a minimum of 5 volts and extra circuitry to use DCC track power, so it was back to the drawing board.

I don't know what to tell you about the cold heat soldering iron...?  Sounds like a bit of an oxymoron to me.

I mainly use a Weller adjustable soldering station now, but have a 35W pistol grip pencil iron that has served me well too.

The nice thing about the circuit I used, based on the LM3909 flasher IC, is the fact that it will operate on a 1.5 volt battery.

Was it excess heat from soldering that fried your LED or was there something wrong in your circuit after soldering that allowed the full 9 volts to flow through the LED?

Anytime you need help with things electrical or electronic just ask.  There are regulars here with some knowledge and training behind them and MRH's Charlie Comstock is very savvy with electronics, among other things.

Here's my few experiances with a Cold Heat soldering Iron

One thing I can say about the Cold Heat irons is that it works for about the first 15-45 secconds of use, then the batteries are so badly drained, that you could place the work in the palm of your hands, and not worry about hot "napalm" solder sticking to you.

With the circut you are working on, it sounds like you want everything under the car it is mounted on. I have a sugestion, which is what I was going to do with my "failed" attempt for a FRED. How about mounting the electronics inside of the carbody, and then cutting a hole in the underframe for the switch? Then, it's a simple matter of running the light for the FRED out to the coupler area (or anywhere you want it mounted) and then turning it on.

As for the LED melting, I have no clue. I tested it by leaving out the switch, and it worked fine, but then I sildered the switch in, and the LED melted. No rhyme or reason that I could find.

Mabe I'll try to swing by Radio Shack, and try it all over again. ( mabe it will work)

FRED circuit

The real challenge in the quest for a FRED is that it has to be easily moved from car to car, just like the prototype.

It's not too realistic to have to run the same car or cars at the ends of our trains because they are the ones with FRED's installed.  What is desired by those doing realistic OP's is a FRED that can be quickly added to whichever car happens to be at the end of the train.

Having the idea was easy.  Making it a reality will take some more thought.

As for switching, If the FRED circuit and power source were inside a box car or the car load I think I would use a latching reed switch that could be operated with a magnet without opening anything up.  With everything being under the car, the switch needs to be small.  I might still use a reed switch but still thinking about that.

If it were G-scale it would be pretty easy to do I think...but since the fellow who asked for it models HO...not quite as easy.