What Size Resisitors do I need for LED's- Update April 22, 2017

Did you read the instructions that come with the FL-2?  Unless Model Power bought some special LED's, they're standard 20ma LED's, the instructions in the FL-2 document should be sufficient.

Thank you John. I had a feeling I would get a response from you

I did read the instructions, just wanted to confirm before I take them apart.

Bob

From the instruction PDF...

The LED Limiting Resistor Values in Ohms limits the current to about 12 ma. So it's depending on the voltage...use Volts/12 ma = resistance

For example if you power with 12 volts AC or DC (observe polarity), then 12 V divided by 12ma = 1000 ohms or 1K ohm resistor and rate the resistor at 1/2 watt.

This is the instruction PDF

Thank you Chuck.

Oh...too late. GRJ helped you. I was having an issue trying to copy the list of suggested values and paste it in a post. That is why I posted how to derive them. How did you copy off the PDF file and post here while maintaining the structure of the table John?

Chuck, I use a screen capture program called Snag-It.  I just snap the picture of a piece of the PDF, and then copy it directly into the post.  Works great and is very quick.  You can do the same with most any screen capture application.  Note that the picture of the table is a graphic, that came right off my screen.

The more the merrier . I'll post some photos when they are installed.
GRG- I like the screen capture program, very easy and better than using print screen.

Bob

If you want a free capture tool, try Capture Screenshot lite, looks like it should do the job.

gunrunnerjohn posted:

Chuck, I use a screen capture program called Snag-It.  I just snap the picture of a piece of the PDF, and then copy it directly into the post.  Works great and is very quick.  You can do the same with most any screen capture application.  Note that the picture of the table is a graphic, that came right off my screen.

Oh...dumb me. I have one called "snipping tool" that was buried on the tool bar.

Here's what it did...

How about that?

Thanks so much John!

I set up and wired the relay and flasher board for the signals. I added the resistor as recommended by GRG and CJACK (Thanks guys). I am getting a double flash on the LED's and am now wondering it a diode will solve the problem.

Again- help from the experts is much appreciated.

Bob

Bob

If the relay isn't bouncing, it's something about that flasher circuit.  Since I have no idea how that's designed, I can't really offer any more insight.

Well, the way I read the instructions, they tell you to put a single resistor in the COM lead and tie the other side of the LEDs directly to the L and R terminals.

It looks like you have done it differently, you have 2 resistors, but I can't see for sure all the detail due to the tie wrap holding all the wires together. I'd review your wiring, do it in accordance with the instructions and see what happens. I'd also verify the polarity of the LED connections, strange things can happen in common return circuits if they are mis-wired.

 What are you using as a power supply?

gunrunnerjohn posted:

If the relay isn't bouncing, it's something about that flasher circuit.  Since I have no idea how that's designed, I can't really offer any more insight.

Thanks for the reply John. No the relay is fine. I will play around with it some more. Not the end of the world if I leave it the way it is. I may check with Circu-tron also.

Bob

What's curious is it seems there are instances when BOTH leds are on at the same time - at about 12 sec and 22 sec into this slow motion version of your video.  As GRJ suggests this seems like something in the flasher circuit.  Did you answer the question about what exact power source you're using?

Also, did you end up going with 1000 ohm resistors?  I was trying to confirm the color bands on your resistors but can't quite make them out.

stan2004 posted:

Also, did you end up going with 1000 ohm resistors?  I was trying to confirm the color bands on your resistors but can't quite make them out.

Stan- yes they are 1K ohm 1/2 watt resistors. I am using 12VAC from the accessory terminals on a CW-80 to test.  On the layout I have a KW. In slow-mo I see both of them lighting up. Good catch, I didn't notice that.

Bob

It even appears there are intervals when both LEDs are OFF.  And intervals when one or the other LED is at some fraction of full brightness.  As described by their own literature the digital timing circuit should alternate with one and only one LED on at any given time...and when an LED is "ON" it should be full ON. 

While it would take a few minutes to troubleshoot using a scope, I figure you don't have one.  So I suggest you ask the manufacturer and maybe provide a link to the video.  This is a very curious behavior for a relatively simple circuit.  I understand just letting it be, but if you choose to dig deeper please let us know any discoveries. 

stan2004 posted:

It even appears there are intervals when both LEDs are OFF.  And intervals when one or the other LED is at some fraction of full brightness.  As described by their own literature the digital timing circuit should alternate with one and only one LED on at any given time...and when an LED is "ON" it should be full ON. 

While it would take a few minutes to troubleshoot using a scope, I figure you don't have one.  So I suggest you ask the manufacturer and maybe provide a link to the video.  This is a very curious behavior for a relatively simple circuit.  I understand just letting it be, but if you choose to dig deeper please let us know any discoveries. 

I contacted Circutron this morning and I have them stumped too. They suggested powering the board with DC instead of AC so I am going to try that and see how it goes. I am going to get the other cross buck set up also to see if it is a load (or lack of) issue.

Thanks

Open note to GunRunnerJohn and Stan2004-

I figured out the problem. THE LED'S IN THE CROSSBUCKS FLASH BY THEMSELVES

I ran 12VDC directly to the signals and the LEDs were blinking away happy as could be. Guess I need some new one's now. I will let the service tech from Circutron off the hook now too.

Just to verify my test, I hooked up a couple of LED's that I know do not blink to the board and relay and they work perfectly.

Thanks again for your help.

Bob

Obviously, you have the flashing LED's, where what you need are the plain LED's.

gunrunnerjohn posted:

Obviously, you have the flashing LED's, where what you need are the plain LED's.

Would be nice if Model Power had better specs for their products. I did remove a small flasher (I thought) module- must have been an alternating relay,  from the bottom of the sign posts when I took them apart. Chalk this up to experience. If everything worked the first time we set it up we would have our layouts done in 5 minutes.

Guess I have some lights for fire trucks and radio towers now too!

Thanks again. Bob

Picked up an assortment of LED's this week. I swapped out the flashers for constant on LED's. Works MUCH better now. Next step to finally get them installed on the layout.

Bob

Looks good, I think you have it.