chris a posted:...
I have been using the capacitors on the coil contacts, basically my DC + is set at 10 Volts at the PW lionel DC transformer, then the capacitor brings it up to 12 VDC +/-.... I am not familiar with adding a "resistor" to this filter. I wouldn't mind hearing the how & why so I can add this to the mix. I have an ample supply of resistor's capacitors etc.
The resistor limits the current surge into the capacitor at the coil when a wheel axle initially straddles the outer-rails. That is, an uncharged capacitor behaves like a short-circuit when a voltage is suddenly applied to it. This surge can cause arcing and, over time, pitting of the rail. Depends on many factors like the power supply, the capacitor size, etc. and you may never see it. But why not pony up a 1-cent resistor. Something like 22 Ohms 1/4 Watt. Go below 10 Ohms or so and you lose the effect, go above 47 Ohms or so and you might starve the coil of voltage.
I don't know your coil current but to achieve any useful chatter suppression the capacitor value will need to be in the 100's of uF. So this will be a polarized electrolytic type rated at, say, 25V or more.
chris a posted:...
GRJ, sorry for getting way off topic on your thread - RR Track Signal Control Board..
Well, GRJ's board will need to handle this application though presumably without relays. A method to "daisy-chain" block signals is a must-have feature. Additionally, I'd think an LED flicker suppression method (like the capacitor across the coil) is another must-have feature. So I think we have his attention!
As for those additional LEDs. Assuming they are also common-anode with built-in resistors, then it seems you'd just hook up a 2nd, 3rd, etc. LED in parallel to turn on at the same time as any of the primary RYG LEDs. Of course this limits you to the 3 existing states and there's nothing new...not very interesting.
I am ignorant as to prototypical signal behavior for your additional LEDs, but let's imagine a new "state" where you want an LED to indicate that a signal two blocks ahead is either Yellow or Red. This logical "OR" can be implemented with 2 penny diodes. The logical "AND" function is a bit more complicated to implement. It's these more complex signal behaviors where I think GRJ's control board will make its mark.