With versatile permanent magnet DC motor speed controller

Shaft positioning MJB Electronics manufacture two basic permanent magnet speed controllers.  That will automatically set up a process like the flow rate controller shown in the example on the right. This application requires a reversing option. Pump Control System two is not designed to move levers but control the flow rate of dosing pumps and other equipment where speed control is required

Four shaft positions with ramp up and down controls

Our dc motor controller can turn a shaft, position a lever, set a slipper valve, adjust a door or louver. These components can be moved automatically to any one of four presentable positions available on the controller.

The motor speed is gradually ramp up as the lever moves away from the current position. As it nears the newly selected stopping point signals from the feedback sensor causes the motor slow down until eventually stopping at the selected docking station or position.

Ramping down the motor before stopping allows precise positioning of components as the docking speed can be set to the absolute minimum to prevent overrun. This function normally alleviates the need for a brake, especially if a worm and wheel gearbox is used to couple the motor.

Information from the shaft or lever position sensor [Usually a simple potentiometer] is fed back to the controller. The position of the lever is compared with the required position and if necessary the DC motor moves the lever accordingly.

In the case of a lever requiring four stopping points through a 360° Radius, three potentiometer would be required to set the lever position at say 90° intervals. The fourth station or stopping point would not normally need adjusting as this position is the stating point and in the absence of a signal, the lever moves to this point.

The lever positions are sometimes selected manually using simple 4 position switch. Alternatively, the signal from a sensor can be compared with the required lever position setting, using a simple electronic quad comparator circuit.

Pulse width modulation is used to control the motor shaft speed. A feed back sensor is not required with this controller, as it uses feedback from the motor armature to set the duration of the pulse.

Two basic models one for levers & one for servo controlled feed motors and pumps 

There are two basic models of our DC motor controller, model DCMC2 provides the facilities ramp up and down, move a lever or some other component to any one of 4 user set positions. A feedback potentiometer is required to send a voltage signal back to the controller to confirm the levers position and also when to reduce shaft speed and stop.

The other model DCMC3 has the same speed controls as the DCMC2 but does not reverse automatically or provide stopping points. This controller is mainly used to control peristaltic and dosing pumps, but has provided useful for many other applications. A on board servo feedback system can automatically adjust shaft speed in response to information from a sensor.

For instance when a pH sensor is used to measure the required dose of a neutralizing alkaline solution to be mixed with acidic liquid. 

This controller can be used with measuring devices using the standard gradual ramp down and gentle stop option in a measure and cut application.

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