CL lighting circuit

[cteno4]

So I'm starting to think about CL lighting now that my first Tomix power pack is coming.

 

What does Tomix use in their lighting kits? Is it a rectifier and resistor to allow both directions? Do they do any additional stuff for the pwm for the LEDs?

 

A cap after the rectifier should charge and keep the led lit between pwm pulses, correct?

 

Jeff

Edited January 4, 2016 by cteno4

[inobu]

"A cap after the rectifier should charge and keep the led lit between pwm pulses, correct?"

 

I think this is simulated with the Ardinuo led programming kits. The programs runs so fast the the LED seems to be solid yet we know that we entered off cycles in the program. Its not until we enter delays that we are able to see the transitions.

 

I think adding the cap may fill in the off cycles but I don' think the eye can detect it anyway.

 

Inobu

[kvp]

Actually both works. One relies on the high frequency flashing of the led with a slow fade, the other method uses a cap to really store enough energy to keep the led lit between pulses. The latter is actually better. Btw. a single diode and cap pair works nicely for directional lights.

[cteno4]

thanks, just wanted to make sure. will go for a larger cap to try to get rail hickups as well!

 

the tomix lighting units just have the rectifier, correct, no cap.

 

time to experiment some when the new tomix controller comes in!

 

jeff

[mrp]

Tomix lighting boards use a full-wave bridge rectifier (2 x SMD dual-diode chips), a 1uF ceramic cap (across the bridge output) and a 1K current limiting resistor in line with the LED.

[katoftw]

wiring diagram?

[mrp]

wiring diagram?

 

 

[cteno4]

thanks mrp, all makes sense. guess the 1uF is just enough to get to the next pulse. ill be beefing it up with a tantalum to get over dirty spots.

 

im just going to use a little MB6S smd bridge rectifier to play with.

 

jeff

[inobu]

Bread board it and add a monetary switch to test and emulate pickup action.

 

Inobu

[cteno4]

Inobu is actually a little Sprite that sits on my shoulder... (But I have a more yoga like picture of him in my head)

 

Exactly what I will do! Tomix throttle will be here in a week or so! Will probably do some with pots to be able to tune the lights until I settle on where I want the stand resistor level to be.

 

I wish bandai was still selling the pickup trucks, would love to light more shorties. Oh well I have a few dozen of the trucks... I could make pickups for the kato trucks but that gets into a much fiddly project!

 

Jeff

[HantuBlauLOL]

I think the resistor should be before the cap.. Also I don't think 1uf would be enough.

[cteno4]

I think 1uF is what Tomix uses and may be just enough to keep the led from cycling. I plan to go up to 100uF to try to get rid of dirty track dims.

 

I think the resistor is after the cap to allow the cap to get full current to charge better, but I'm working on 40 year old electronics class memory...

 

Jeff

[kvp]

Yes, the cap must charge quickly but discharge slowly, so bridge, cap in parallel, resistor and diode in series.

 

ps: Plase take into consideration the number of cars in the set as the first charging can cause quite a lot of inrush current if the overall capacity is too high.