Motor Control Unit
|Introduction||Constant Voltage||Pulse-Width Modulation||Design Ideas|
It has been an aim of mine for several years to control my model railway by computer. As part of this project it is necessary to develop a circuit that can control the speed of a motor. The original aim was to control the motors fitted to the trains themselves, however other accessories such as turntables can also be controlled in a similar manner.
To me, an important part of the project involved allowing individual motors to be controlled manually if required. In later sections, I will shew how this can be achieved, using electronics to allow manual control if required. Further, it is quite possible to build the circuits shewn here for manual control only, if that is what you are after.
As part of the design process, I considered several designs. Whilst some designs worked, others were not quite so effective. Some of the unsuccessful designs are indicated at the end of the section for informative purposes.
The first design uses a variable voltage regulator to provide a steady voltage supply. Using this design the motor develops the least amount of noise, however some motors of poorer quality tend to stall more easily.
For full details, consult the Constant Voltage Controller page.
This design uses the "Pulse Width Modulation" in order to provide more torque at lower speeds. This reduces the number of instances when the motor stalls, and provides improved low speed running. As a result, trains pull away from start more smoothly.
For full details, consult the Pulse Width Modulation Controller page.
For a summary of less successful designs, please consult the Design Ideas page.