Determine the Resistance that must be Connected to the base Lead of a Transistor

A resistor will most likely be needed at the base lead of a transistor if the transistor will be used as a switch. The formla below is a special formula that is used only if the supply voltage is the same as the voltage being applied to the base lead of the transistor Resistance = LoadCurrent x LoadResistance x Hfe(transistor rated)

Example: R = .2 amps x 25 ohms x 200 = 1000 ohms or 1k