That's a great idea

That's a great idea. Do you have details on how you put it together?

details

At my blog I've more pictures.

I've used 0,1mm magnetic wire, drilled a hole from the foot to the head. Flaggy is glued to PC board tie. There I've installed three (!!!) brass angles and a 1,5 kOhm resistor. This way I can place him at any track, even H0n3 track.

Wolfgang

Mad props to ya!  That is

Mad props to ya!  That is awesome, quite the departure from little folded bits of paper most of us use.

Josh

idea

I've got the idea from Laurie at the Hon3 list.

The hardest part was soldering the two wires to the SMD LED. The first one left my tweezers and I found it when I finished the flagman. But I had some experience. For my steam engine type ELNA I've used about 20 LEDs. For six lamps!!!

Wolfgang

+ +

Nice work.. Now the next step is to animate him so he waves his arm.

Marc Fournier, Quebec

Heat wire

Perhaps using some heat wire, or a bi-metal strip, with track current through it for the heat source.  The metal bows or straightens at different temperatures.

You would also need an interrupter circuit.

A bimetal spring would move one way when electicity was applied, but if it doesn't turn off the arm only moves one way, never returns to position.  Therefore you need to turn on power to get the arm to move one way, then turn off power for the arm to return to original position, then turn power back on, etc to get him to wave the lantern.

interupter

Sorry, I only wrote half of my thinking.  As the metal heats and moves, it breaks the circuit, and so cools.  Then it moves back and then re-makes the circuit.  The old-fashioned automotive flashers worked on this principle.  That's why, when you plug in trailer lights, the flash rate was so much faster:  bigger load, more current, more heat faster. 

I've used heat wire in large applications to move shutters or dampers.  And I've seen small wire available, I just haven't used it.  Maybe an old thermostat with the coiled bi-metal strip could be the source of parts.  You shouldn't need much length, because you only need to move a small distance.

I just remembered (or I think I remember:  it's tough when you're over 60) that there was an MR or RMC article 10-20 years ago about heat wire for operating crossing gates.  Anyone recall?

Flagman w/ light

Wolfgang,

A oh so cool detail!  Thanks for sharing!

Rick

Heat Wire

Yes, there was an article using shape memory wire; nitinol of flexinol, etc. in MR for sure.  About 10 years ago sounds right.

I have read that it only performs well and reliably over time if it is driven with a PWM circuit rather than just applying power.

DCC or AC?

I can see this guy working fine under DC power... how about AC/DCC track power? Do they make a rectifier that small?

Don't need a rectifier

Jeff,

You don't need a rectifier for DCC.  The LED will just be on for the half cycle where the current's flowing in the correct direction, and be off the other half.  If you're able to detect it, it will just look like a realistic flicker. 

Under DC, depending on the track polarity, it may be off, period.  There's where you'd need two LEDs wired back to back, so one is lit or the other, depending on polarity.

DC

For DC you need more than a resistor like I used. Some device which will give you the current the LED needs. Such a device would need perhaps two transistors and.... Quite a small PC board. And this will be another challenge to get this at the PC board tie.

That's another plus with DCC, this guy will always have a lit lantern.

Wolfgang

How To

I've made another flagman, this time with quite a few pictures. Here's my How To.

Wolfgang

Poor man's flagmen

In the meantime, if you need flagmen within the next 15 minutes, there is this source:

http://www.railsonwheels.com/ors/flagmen.shtml

Great How To

Thanks I enjoyed the how to.  Now lets figure out how to have him wave his arm...

 That steam loco is something

That steam loco is something else. I remember enough German to catch maybe 1 word in 100, but the pictures tell the story. Yet another amazing piece of work, doesn't surprise me it comes from the hand of Wolfgang after seeing some of his other work.

As for LEDs and DCC, the really should have either another LED or a regualr diode wired anti-parallel to protect them from the full voltage in reverse. A regular rectifier diode can have ratings of 50, 100, 200, 400, or more PIV - peak inverse voltage. An LED, not so much. A common workaround for track power indicators is the use of a bicolor LED, which has the bonus ability to show if address 00 is dialed up and zero stretching is happeing. Not real practical for something this small when you want a red light, not an orange one. A surface mount regular diode across the gap cut in the PC board tie would handle it.

--Randy