How to

As the train approaches a set of points I want it to be able set the points in a particular direction. Now I have seen it on an old Lionel tinplate layout. The Yanks were certainly into gizmos for their model trains a long time ago. Never seen anything similar for any or our major manufacturers though.

My thoughts are a switch operated by the train. As it needs to be once only and fairly quick it needs to be simple, but not easily interfered with.

so far I have considered:

1. micro switch in track activated by a cam piece on the train
2. two contacts shorted by a plate under the train
3. as 2 but one contact only return being in track
4. magnet on train activates small switch. Below train or just to the side with magnet inside train.

I am leaning towards a magnet in the side of the train. This has the benefit that magnets on different sides of the train had different effects on the points direction.


Any solutions tried and tested?

Thanks in advance.

David

Reed switches operated by magnets on the tram/loco would probably do it.

Hi David,

I think you have already talked about using all 3 rails for passing information using short isolated sections. Marklin 3 rail (studs) have a sophisticated system, it may be that Marklin users have solved the problem.

Basically all you need is a way to detect the tram, and in my opinion it is better to do it electrically than with, say, reed switches, which can be tricky to adjust.

MERG circuits use op-amps a lot. My MERG superbloc controllers use them, four in one LM324 chip, for two detected sections per controller. You have built a circuit with a 555: op-amps are much easier to understand and set up. How about a little detector circuit with an op-amp to switch the points and possibly a 555 to latch them?

It depends how you change the points: Solenoids, tortoise/cobalt or some other way.

Hi David, 
Have a look at Heathcote's IRDOT system. They have one to operate solenoid switch motors.
Nigel 

IRDOT-P automatic point control