Microcontroller chips do wonderful things, but they can be a support hassle. Unlike most consumer electronics replaced or retired after a few years, model train electronics can be used for a lifetime. Good luck obtaining a replacement programmed microcontroller like a PIC from even 5 years ago – especially if Microchip stopped making them or if the programming tools ran under, say, DOS connected to the Centronics parallel port or some other no longer supported environment. OTOH, the 555 is over 40 years old and you can still buy them at Radio Shack!
Originally Posted by rrman:
Besides I enjoy designing with discrete parts. I know there are ready to go flasher boards out there for alot of money that has a few parts on them that will do the slow on off and detection, but whats the fun of that?
Indeed.
5 cent transistors in a paired emitter-follower configuration with a single R-C time constant can achieve a suitable effect. One after the master 555, another after the inverting buffer slave 555.
For some reason the ramping effect does not show up that well in this video but I think you can see the difference when the cap is removed.
