Control the intensity of a direct current of up to 3 amps in a load. The complete rheostat circuit is shown in figure 1.
Utilities:
• Dimmer of direct current controlling brightness of lamps or speed of motors of direct current.
• Applications in robotics and automation
• Brightness control of car or engine panel lamps
• SMA drive control
Constructive Details:
In figure 2 we give a suggestion of printed circuit board for the assembly of the rheostat.
Note the thicker tracks for driving the main chain.
The transistor must be equipped with a heatsink compatible with the intensity of the controlled current. The input voltage must be at least 1 V higher than the highest voltage to be applied to the load. Potentiometer P1 must be wire.
Semiconductor:
Q1 - TIP41 or equivalent - NPN power transistor
Resistors:
R1 - 470 ohm x 2 W
P1 - 1 k ohm - wire potentiometer
Several:
Wires, solder, heat radiator for transistor, printed circuit board.
