Principle of Operation.

The Capacitor Discharge Unit (CDU) stores up power in the two electrolytic capacitors. When you operate the switch on your point motor, the capacitors discharge all of their energy instantaneously. This gives the point motor a huge burst of energy which moves the point blades to the desired position.

Once the capacitors have discharged they can only be re-charged once the switch is disconnected from the point motor coil. This takes milliseconds to happen and the unit is charged ready for use again.

Using a CDU is also useful for preventing point motors burning out. Without a CDU, if the switch develops a fault (left connected to point motor coil) it will cause the point motor to quickly burn out.

Application.

The CDU can be powered from any AC or DC source. The power supply should capable of delivering between 12 – 24 volts at a minimum of 1.0 Amp and not exceeding 5.0 Amps. The higher the voltage the more points the CDU will be able to move at the same time. This CDU is designed to operate standard, solenoid type, point motors. (Hornby, PECO and SEEP). This model will enable you to switch up to 10 points simultaneously (depending on condition of points and motors and power supply used). Only one CDU should be required to control all the points on your layout.

A Capacitor Discharge Unit is particularly useful for stud and probe point motor mimic panels were there is only a brief contact of the probe on the stud to operate the solenoid. Which without a CDU may not be enough to throw the point fully?

*No harm will come to the CDU if these are incorrectly connected.