Hornby Points motors

[mobi323]

I have recently began to wire up a Hornby points motor. I have a SPDT switch with a momentary on function which springs back to the central off position when released.

 

I have attempted to wire the motor from the 15vdc aux power supply from my Hornby Select controller. This has been a dismal failure as every time I throw the switch in either direction the motor works but it gives a momentary short and the controller changes to the default setting of "3". (It is not a track fault as the result is the same when the motor is removed from the points and it is operating while not connected to the points).

 

I even tried powering the points from the track supply. This appeared not to work so I didn't muck around much trying different wiring combinations in case I did some permanent damage.

 

I have a spare Hornby transformer (It came with a Royal Scot set). I had a look at the output voltage and it is 16 vac. The specs for the points motor says either 12vdc or 15/16 vac. So I gave it a try. It works perfectly.

 

The Select controller's output voltages are :- Aux - 15vdc and track power is 17-18vac the last time I measured it.

 

 

Am I missing something or is the Hornby Select's auxiliary voltage too high for operating the Hornby points motors?

[smokebox]

The standard power supply of the Select simply is not sufficiently powerful enough to drive point motors (solenoid type) directly. The power supply is only rated at 1 Amp and point motors take 3 to 4 amps, hence the Select resetting. You can add a CDU to the circuit and the points will then work properly or replace the 1 Amp power supply with the Hornby 4 Amp one. Other alternatives are to use a laptop power supply (make sure the polarity and voltage are suitable) or one from another supplier such as Maplin. Your solution is probably the best as it keeps the points supply and the track supply totally independent.