Model Railway Switches - New Railway Modellers

I know what you're thinking switches are easy, but point motor switches are not like normal switches. A point motor requires only a short burst of electricity. Hornby use what is called a passing contact switch. This means it only supplies a short burst of electricity to make the points change. The problem with Hornby switches is their cost (£5 RRP). This means they cost more than the point motor (£3.85 RRP) and together with the cost of Hornby standard points (£6.50 RRP) the cost of each motorised set of points is a whopping £15.35 RRP. That's £30+ for a set of change over points and £60+ for the return.

I strongly recommend that you use toggle switches (on-(off)-on) or two push switches which are available form any good electronics firm or New Modellers Shop. These switches return to the centre when pressed so that you only supply that short burst of power, that the point motors need. Point motors can burn out if you don't use a short burst of power. A Capacitor Discharge Unit will help protect your point motors.

I would also recommend toggle switches for the signals (on-on) as well as any lights or isolating sections you have (on-off) as Hornby alternatives are also £5. A standard toggle switch should be about 20p.

There are advantages of using Hornby's system. All three types of switch, interlock to make an attractive and functional switch board and because they are large, you get the feel you are in control of a real railway. Unlike the toggle switch, the Hornby switch shows the position of the points either open or closed. The toggle switch returns to the centre when it is pressed and thus does not show the position of the points. If you haven't got a good memory then you will have to use the Hornby point switch. The Hornby switches are also spring loaded in one direction. If cost is not a problem I would go for the Hornby switches (point switches especially due to showing the points position) especially if the layout is to be used by children.

Point motors need to be wired independently to its switch. It is only the centre wire (in my case black) of both the point motor and switch which are wired to the low voltage power output and can share a wire with other points. See the circuit diagrams below. On the left you can see three point motors connected to three toggle switches. On the right you can see three point motors connected to six push button switches (one for open, one for close on each point).

SPDT (on-on toggle switch) And Push To Make Point Switching (Idea from Mr Bulmer)

This method of switching point gets around the problem of not knowing the position of the points. By using an on-on switch to change the direction of the point motor, and a "push to make switch" to activate the movement. (See circuit diagram below)

The on-on switch directs the power to either side of the point motor. If this was connected to the power supply the point motor would burn out as it would get a constant flow of power. By putting a "push to make switch" between the on-on switch and the power transformer, you can trigger a short burst of power to change the point.

So to change the point you position the on-on switch, and then push the "push to make switch" to trigger the burst. The position of the on-on switch illustrates the position of the point. It would be a good idea if you position them on a control board with a diagram of the layout so you know what the switch position means.

Problems: The position of the on-on switch, does not tell you if the point has actually changed. The only way to show the position of the points remotely, is to fix a switch to the point which changes a light on the control board. If you do this you might as well use the toggle switches (on-(off)-on) or two push switches.

Warning point motors can burn out if you don't use a short burst of power. A Capacitor Discharge Unit will help protect your point motors

Advantages: Less wiring than using lights to illustrate the position of the points and its cheaper.

Instead of using a push to make switch, this method uses two diodes and a capacitor to fire a short bursts of power to throw the point switch. (see circuit diagram below)

When the switch is thrown, the current flows through the point motor until the capacitor is fully charged and then it stops. When you then through the switch in the opposite direction the capacitor discharges through the other side of the point motor making it move in the opposite direction from before until the capacitor is fully discharged. Both times the switch is thrown the point motor only gets a very small burst of power.

Problems: Only the added time in wiring which makes this more complex. I have only run this on a test rig using 12v DC and it works but with little power. I think you need the 16-24v which was suggested.

Advantages: Only need one switch. Basically it works like Hornby and Peco point switches except it requires DC to work. You should not require a Capacitor Discharge Unit as the capacitor does this job.

Mimic Board Another method of changing the points is using a mimic board. This article was written by Mr Breakwell

"If your after cheep way of wiring point motors, terminate the two wires from your motor directly on your control panel with self taping screws. Terminate the power wire (from the controller) the same way in the upper centre of the panel. You will need to extend the power wire with a trailing wire. This should be a strong flexible multi core wire (the type used in cars) Fix one end with a spade fitting to fit under the screw to contact the power wire and the other end can be cut off clean leaving the wire insulated."

"To operate the point touch the trailing wire on self taping screw you'll find you have to hold the trailing wire vertical because of the insulation (do not keep it in contact, just one touch should do) I have made a diagram to assist my explanation."

Click here to enlarge image

"There are two problems.

1. You may have to reverse the wires from the points to activate them on the correct track.
2. You can't identify from the control panel, which track was selected last ? This can be solved using a Peco Accessory Switch (PL-13) which is mounted on the point to change an led on the control panel to indicate the position of the point (green for straight and red for bend). This could also change a signal at the same time.

3. Warning point motors can burn out if you don't use a short burst of power. A Capacitor Discharge Unit will help protect your point motors

Advantages: Very Cheap!!

Electronic component retailers are an endless source of cheap electronic components that will allow you to do almost anything to you layout. You can find a selection of the components I have used at this site new modellers shop

Model Railway Electrics - Switches