Hello
I'm trying to design a simple circuit for switching point (turnout) motors on a model railway and found this circuit on a railway website, please see the attached jpeg.
The point solenoid on the left needs a short burst of current to switch the point one way or the other, since constant current would quickly burn out the solenoid.
The switch needs to be two position spdt switch. You could wire this circuit just using a couple of push button switches, but the advantage of the spdt switch is that you can see at a glance from the switch position how the point was last set.
Do you think this circuit would work please and can you suggest any improvements?
The circuit description says "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 throw 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."
When it is fully charged would the capacitor block all DC current reaching the solenoid, or would a small amount still trickle through?
The circuit relies on the capacitor discharging to switch the point back again. If you switched the point and then turned the power off, (ie. stopped using the model railway for a while), wouldn't the capacitor slowly discharge on it's own? So that when you returned there would be no power left to switch the point back again?
Thanks for your advice
I'm trying to design a simple circuit for switching point (turnout) motors on a model railway and found this circuit on a railway website, please see the attached jpeg.
The point solenoid on the left needs a short burst of current to switch the point one way or the other, since constant current would quickly burn out the solenoid.
The switch needs to be two position spdt switch. You could wire this circuit just using a couple of push button switches, but the advantage of the spdt switch is that you can see at a glance from the switch position how the point was last set.
Do you think this circuit would work please and can you suggest any improvements?
The circuit description says "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 throw 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."
When it is fully charged would the capacitor block all DC current reaching the solenoid, or would a small amount still trickle through?
The circuit relies on the capacitor discharging to switch the point back again. If you switched the point and then turned the power off, (ie. stopped using the model railway for a while), wouldn't the capacitor slowly discharge on it's own? So that when you returned there would be no power left to switch the point back again?
Thanks for your advice
Attachments
-
10.4 KB Views: 210