Multi-voltage Control for Mechanical Sensors (MEC184E)

This text was taken from my book Robotics, Mechatronics and Artificial Intelligence (sold out) published in the United States. It shows how to build a multi-voltage control for DC motors suitable for mechatronics or robotics projects with microcontrollers or as a building block for simple projects.

Many sensors (reed switches, home-made sensors, etc.) can be used to generated different voltages in a load. The block illustrated in Figure 1 shows how this can be done using a single LM350 IC. This IC can control up to 3 A in a voltage range from several volts to 25 V, as in the previous article (MEC183E).



Figure 1   Multi-voltage control
Figure 1 Multi-voltage control



When all the sensors are open, the voltage found in the output of the block (across the load) is determined by Px. This control can adjust the output for voltages between 1.25 and 25 V.

When any sensor is closed, the voltage changes to a value determined by the adjustment of the corresponding variable resistor. For instance, when X1 is closed, the output voltage falls to a value determined by the value of P1 and Px in parallel.

The LM350 must be mounted on a heat sink, and the input voltage must be at least 3 V higher than the maximum programmed voltage in the output. This block can be controlled by a drum position sensor as described in the Section 9.2, on theory. Many blades can make contact with a drum (cylinder) where the voltages are programmed according to the position. Another suggestion is the use of a microcontroller for this task.