Jbb posted:...
- Instead of using the bridge rectifier, should I get a cheap DC transformer, especially if I plan to use some LED lights down the road?
- I think for each block I need one DPDT relay, a bridge rectifier or a DC transformer, a capacitor, and some resistors if that method is preferred - can I get some part numbers from someone's preferred supply house?
As I mentioned in above post, if you go with an isolated 12V DC supply as what gets switched across the outer-rails, then you don't need a bridge rectifier for each relay. You would still need/want a capacitor for each relay for anti-chatter chosen as GRJ describes.
Like you say, you can find "cheap" DC transformers. For example for about $3-4 on eBay (free shipping) you can get a regulated 12V DC, 2 Amp wall-wart style transformer. Here's a recycled photo from another thread showing a 1 Amp wall-wart and use of an adapter jack (about 50 cents on eBay) so you don't have to mess with cutting the plug and splicing wires. There are zillions of 12V DPDT or SPDT relays as you have discovered but for the application at hand let's say each requires 50 milliAmps of coil current. Let's say you go with LED signals that draw, say, 10 milliAmps of current and are powered by the 12V DC relay supply. Then a 2 Amp (2000 milliAmp) supply can power over 30 relay + signal LEDs. And of course you can get 3 Amp, 4 Amp, etc. regulated 12V DC supplies for just a few dollars more.
