This circuit can be connected to any power supply or batteries from 3 to 12 V and can produce currents up to 3 A with the recommended transistor. The transistor can be installed on a heat sink. For currents up to 2 A, the transistor can be replaced with a TIP31, and for currents up to 1 A with a BD135.
Figure 1 – Rheostat for SMA
You can also invert the polarity of the power supply and use PNP transistors.
