transducer driver

Processor that drives an output in an electronic system. It has a current gain, which means that a low input current from a sensor or switch is amplified in order to operate or drive an output transducer that needs a higher current.

A transistor is an example of a transducer driver. It has three ‘legs’ – a base, a collector, and an emitter. To activate a transistor a low current is sent to the base leg. A protective resistor is always attached to the base to keep the base current low and to protect the transistor from damage. Once sent, the base current allows the transistor to saturate with ‘electrons’, which allows the semiconductor material inside to conduct electricity. The output is usually placed between the positive supply and the collector leg of the transistor. The current flows to the collector and out to the negative supply via the emitter leg.

There are two basic types of transistor: an npn transistor and a pnp transistor. The example above is of an npn. A pnp transistor works the other way around, with its collector current attached to the negative supply and the emitter attached to the positive supply.

A transducer driver not only amplifies an electrical signal but also acts as an electronic switch. For this reason transistors and other transducer drivers are basic components of integrated circuits.

The gain of a transducer driver subsystem can be increased by placing two transistors in series. The total gain is found by multiplying the gains of the two individual transistors. This combination is called a Darlington pair. Darlington pairs can be obtained as a discrete unit. For outputs that require higher currents a field-effect transistor (FET) can be used. This also has three legs, a gate, a drain, and source. FETs have a very high gain and are voltage-activated rather than current-activated.

Thyristors are transducer drivers that can be latched. They have three legs: an anode, a cathode, and a gate.