Alternating ditch lights off of one decoder output?

Here's a question that I have just started pondering.

Can I run alternating ditch lights off of one decoder lighting output?

I only have one unused light output on a ESU lokpilot 5 micro decoder, so I was wondering if anyone has a suggestion on how to do that?

I am working in N scale, so the solution has to be small.

Is it as simple as wiring one of the LEDs backwards?

I think that depending on the voltage ramp, they could both be on or off at the same time? Does anyonme know what the ESU ditch light voltage profile looks like?

The LEDs I have turn on at 3V, so I think both lights will be off when the output is between 0-3V. This isn't quite the ditch light behavior is usually see

I guess I could hook up a set of LEDs to the one output and see what happens.

Are there any other techniques?

Jim

 

No, you will need two function outputs for alternating ditch lights. The blue wire (common) is generally positive, and the decoder cannot swap polarity like that. (although I like your idea) If you were to have reversing polarity, all your other headlights would flash as well, since everything else is connected to the common lead too.

The most common way to make flashing ditch lights is to share the blue wire, and then each LED is connected on the negative side to a function output. From there, you program those two function outputs to be Ditch Light 1 and 2.

Having both LEDs wired 'back to back' would create a problem when you needed both to be constant brightness. Normally, the ditch lights flash at crossings, but you would need a way to have both on at the same time as well.

 

I see now the one diode backward idea doesn't work unless the function output goes above the voltage of the blue wire.

Having them both on at the same time is not a concern.

Well, how about both of the LEDs are fed by the same function output, but one goes through an inverter IC? That would split the decoder output into two signals that are the complement of each other.

I would just have to find a small inverter IC that can handle the input, which may go to ~10.5 V. The ESU Lokpilot 5 manual says function outputs go to track voltage minus 1.5 V.

Anyone have an opinion on this? Ever try this? I think this has potential.

Jim

 

Just wire one to the reverse light output, then keep throwing it in reverse.

They make special tiny widgets for that now, if you want to take the easy way out.

 

If you know of a "special tiny widget" small enough to fit in an N scale engine, I would like to hear about it, please.

 

You're trying to get me in trouble. We aren't supposed to mention producers of Train Electronics (or anything else) that don't advertise here.

Nevertheless, I just did.

 

There are only four outputs on the Lokpilot (or Loksound) 5 micro that can run an LED. The forward light, reverse light, AUX1, and AUX2. I think you are thinking of the regular version, which does have AUX1-8 available as a powered output, along with front and rear light.

I plan on lighting the headlight (always on), the gyralight/top beacon, the red lights on the front to come on in reverse, and the ditch lights to alternate. That's five, assuming alternating ditch lights need two outputs instead on one.

Your mention of AUX3/4 got me thinking. AUX3 and AUX4 pads are on the back of the die. Soldering wires to them is not really a problem. They would need external transistors to be able to drive LEDs, but I could do that. I'll have to see if AUX3/4 can be set with lighting functions just like AUX1/2.

 

Heh. And the misunderstanding continues...

What I meant by "the regular version" was the non-micro ESU v5, which has the 10 power outputs.

Thanks for the info! You have solved my problems.

Jim