LED-ifying old directional lighting units

[railsquid]

So, I finally got round to doing unspeakable things with a soldering iron and various bits of electrickery to an ancient Tomix Seibu 5000-kei Red Arrow , namely replacing the olde-style bulb (left) with something more modern (right):

 

 

In "daylight" the difference is not so apparent on camera, especially in a still shot  - when voltage changes the brightness change in the filament bulb is very obvious - but to the naked eye the LED version looks much more "train-like".

 

[kvp]

Nice work! And it seems you choosed a cold white led. Adding a buffer cap is more important here as leds tend flicker more easily on contact loss.

[railsquid]

Aha, interesting point, thanks. Any recommendation for type/specification, and maybe a simple circuit diagram? I have literally no idea what to look for.

[kvp]

Generally you could add a small smd capacitor parallel to your led setup (resistor/led pair). The voltage of the cap should be at least 1.5x of the maximal track voltage on your layout, but i would go 2x, so around 25V. Capacitance should be imho as large as you could find in these rice length, blocky smd capacitors that would fit easily. This (along with the already present diode on the track supply) upgrades your circuit to fully Tomix CL compatible.

 

ps: the full circuit is: pickups - series diode - parallel cap - series resistor - led

[railsquid]

Thanks, I'll see what I can find.

[cteno4]

Squid,

 

Smd Tantalum caps can get you a lot of bang in small spaces if there is room in there on be board or you could wire them with short leads.

 

http://www.ebay.com/itm/5pcs-7343-SMD-Tantalum-Capacitor-25V-100UF-Type-D-Accuracy-20-/191190174303?hash=item2c83d28a5f:g:EuYAAOSw-jhT--56

 

Jeff