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Crash Course Electronics/Transistor (view source)
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Transistors are often used to switch loads or to amplify signals. Other uses as variable resistor are also common (for example for level shifting on digital inputs). | Transistors are often used to switch loads or to amplify signals. Other uses as variable resistor are also common (for example for level shifting on digital inputs). | ||
=== Emitter Follower === | |||
The emitter follower useful whenever you have a voltage source which isn't capapble of delivering a desired current. For example a potentiometer wich should control the voltage of a motor is too weak to directly connect a motor. Amplifying a voltage coming out of the potentiometer (used as voltage divider) you can control a transistor which then controls the motor. | |||
The output voltage is approximately equal to the input voltage of this circuit. (it is always slightly lower than the input). So this should not be used to switch a high voltage by a low voltage control signal. It can however be used to switch a load if the control circuit and the supply of the load are equal. | |||
=== Emitter Circuit === | |||
Don't confuse it with the emitter follower. This circuit is useful to switch loads on and off by a small control voltage and a higher (or equal) supply voltage for the load. If a second resistor is added is also capable to amplify a voltage to a higher voltage like the emitter follower - but instead with a low voltage controlling a high voltage. | |||
== Links == | == Links == | ||