FET Fundamentals Unit 1 – Circuit Board Familiarization
UNIT 1 – CIRCUIT BOARD FAMILIARIZATION
UNIT OBJECTIVE
At the completion of this unit, you will be able to identify the circuit blocks and major
components of the FET FUNDAMENTALS circuit board by using the given information.
UNIT FUNDAMENTALS
The FET FUNDAMENTALS circuit board explores the field-effect transistor (FET), the
unijunction transistor, and three transducer devices. Two types of field-effect transistors (FETs)
are discussed: the junction FET and the dual gate metal oxide semiconductor FET.
A unijunction transistor has only one PN junction. Training is provided on this device by
connecting the UNIJUNCTION TRANSISTOR circuit block as a relaxation oscillator.
Transducers convert energy from one form to another, such as a heat to resistance change. Three
transducers, a thermistor, a photoresistor, and a fiber optic link are explored in this unit.
NEW TERMS AND WORDS
transducer - a device that converts energy from one form to another; for example, current to
light (LED) or heat to resistance(thermistor).
relaxation oscillator - a type of oscillator in which the active control device turns off (relaxes)
for part of the cycle.
thermistor - a device whose resistance varies as the amount of the heat on the device changes.
photoresistor - a device whose resistance varies as the amount of light on its surface changes.
fiber optic link - a path that uses light energy to transmit information.
gate (G) - the FET terminal that corresponds to the base of a transistor.
emitter (E) - the current injection terminal of a UJT.
drain (D) - the FET terminal that corresponds to the collector of a transistor.
fiber optic cable - a low loss cable made of glass fibers. It is used as a path way (or conductor)
for the passage of light.