FET Fundamentals Unit 7 – Hartley and Colpitts Oscillators
NEW TERMS AND WORDS
oscillator - a circuit that can convert dc current to ac current at a predictable rate.
positive feedback - a signal returned to the circuit input which is in phase with the circuit input
signal.
regenerative feedback - positive feedback.
feedback signal - the part of the circuit output signal returned to the circuit input.
self-sustaining - having sufficient feedback to maintain circuit oscillations without external
stimulus.
tank circuit - the frequency-determining components of an oscillator circuit.
crystal - a component made from
quartz material. It can be
cut or shaped to resonate
(oscillate) at very precise
and stable frequencies.
mechanical resonator - a nonelectrical component that can oscillate at a predetermined
frequency. Examples are springs, pendulums, or tuning forks.
series fed oscillator - a circuit that has direct current within the tank circuit.
shunt fed oscillator - a circuit in which direct current is not present within the tank circuit.
buffer circuits - circuits that have a high input impedance and therefore do not load down the
tank circuit of an oscillator.
EQUIPMENT REQUIRED
F.A.C.E.T. base unit
FET FUNDAMENTALS circuit board
Multimeter
Oscilloscope, dual trace