chris a posted:...Seems like connecting the Lionel 0100 DC Neg. to the AC Common would be the easiest solution ? If that's so, would it be wise to tie some 220uf or 470uf caps across the contacts for the coils of the relays ? And are there any other I's and T's I should address before I go any further.... And lastly, I suppose I should plan on raising the 10VDC to 12VDC, or will I see an increase if I tie the capacitor across the coils anyway.
I have a bunch of 1N4003's and 1N4004's, alot of 470uf capacitors, and also a bunch of full wave bridge rectifiers that I have accumulated over the years getting ready for where I have finally gotten to....So if there's another way that you strongly recommend, I can solder, and put stuff together, but I also like to keep it as simple as reasonably possible.
Yes. For the purposes of isolated-rail triggering, the negative (DC- as labeled in the drawing) of the isolated DC supply tied to AC Common is easiest.
Yes. Since it sounds like you have a boat-load of 470uF (preferably rated 25V or more) capacitors, I'd put one across each relay coil. This demotes relay chatter particularly when a train enters or exits a block section; that is, at those instances you have only 1 or a few axles closing the relay circuit and any intermittent contact due to dirty wheels, slightly bent track, whatever can cause annoying green-red (on entry) or red-yellow (on exit) flicker on the signal head.
I don't know if this would be classified as an i or t (to dot or cross 
) but when using a relatively large capacitor like this in isolated-rail triggering, it is prudent to place a small resistor (10 or 22 ohm are common values, 1/4 Watt) with each capacitor. You only need 1 per relay and it can be placed in either location shown in the diagram; depending on how your barrier strips are configured one or the other location might be easier. The resistor limits the amount of current rushing into the capacitor when the train first enters a block section. Without a resistor there can be many Amps of so-called inrush current which can cause brief sparking on the wheel-to-track gap. The sparking can cause pitting or "pock-marks" on the contact surfaces which over time degrades clean electrical contact.
Yes. You might need to bump up the DC bus voltage to 11 or 12 or so. You only get that voltage "bump" with AC-to-DC conversion. With a DC bus, the capacitor and relay coil only receives the magnitude of the DC voltage. While most 12V DC relays will trip reliably with 10V you'll get more robust operation at 12V. I'm guessing you won't even notice the slight increase in brightness on your control panel LEDs or signal heads.
BTW, what relay are you using?
