This circuit shows how to use a PNP transistor to drive a load from 500 mA to 1 A, depending on the transistor. For the 1 A transistor, it is correct to use TIP32, as the indicated TIP31 is NPN. The transistor must be equipped with a radiator and S1 can be switches, sensors or reed-switches. The circuit is from Newton C. Braga's Mechatronics Sourcebook published in the United States.
