RC Servo Control

Maybe a Tortoise switch machine motor?

http://www.azatrax.com/working-crossing-gates.html

I don't always give a GA for an internet search.

But, sometimes.....................

The 'bang-bang' speed of the servo is 0.1 s/60 degrees, so you'll never get slow movement unless you use a mechanical damper (e.g. a dashpot) or some kind of proportional control. I don't know if a ready-made solution is available, but the cheapest way to go would be to use a progammable device (e.g. a PIC microcontroller, or maybe an Arduino or Raspberry Pi) to drive it. Not trivial, unless you're already familiar with such things.

I have found only one supplier, Tony Williams in the UK, who has solved this problem. His crossing controller operates the servos nice and slow. I can't tell how he does it by looking at his PC board, and he's not telling, either. Somehow he fits control for two servos, lights, the bell, and two sensors on a playing card sized board. I'm working with him on one for US trains, but am curious as to how it's done.

Have you considered a miniature DC gear motor and some type of lash-up with levers and such?

Yes, lyn, I have built a few crossings,with motors and gears like you mentioned. They are all too complicated, require a permanent train setup, table, etc. I'm trying to build simple, cheap, crossings for folks that put their trains up when not in use. It was all I had as a kid, trains in a box. There seems to be a lack of these for modelers, I'm trying to fill a gap in the hobby.

Try this:

www.instructables.com/id/Simple-and-dirty-Pulse-Width-Modulation

Treaney, I agree PWM is probably the way to go, but I can't see where to connect the third connector on a servo to the schematic from instructables.

That is because PWM is being used in a slightly different way, to drive a brushed DC motor at varying speeds. For that purpose the important feature is the ratio between on and off and the frequency is relatively unimportant. A servo, on the other hand, requires a steady pulsed input, typically every 20msec. The pulse width, in the range 1-2msec, determines the position of the servo arm.
Have you thought of using a standard RC Tx an Rx as a controller?

al@modelrailwaylayoutsplans.com

Try here as this is a model train forum. They are very helpful and I have no doubt someone will provide you the right answer and lead.

Just an idea, but if you learned PIC programming, or even one of those with a simple BASIC interpreter inside, you could program the whole thing very easily.....some of the chips even have PWM outputs already built in an also controlled by the Chip. I use them for small projects for some years now.....

The chips start at around $2. All documentation is free to download, all the software needed is free to download.

Basically you need the chip, a PC with a USB connection for programming, a few tiny motors and a few transistors and other cheap components....

All in all a simply project. Final cost could be well under $20 (carefully done, maybe under $10), plus your own work.....

An Arduino for example is much too much for such a project.....best of luck, start here:-

rev-ed