Author: Florin Mihai Tufescu - associate professor "Al. I. Cuza" University of Iasi
Year of publication: 2020
What are passive circuit components?
Passive components consumes the energy of electrical signals but they are necessary in the operation of all circuits, because they provide voltages and currents at different points, regulate power levels, delimit its frequency bands As a number, passive components are predominant in the total components of a circuit or device.
Their quality will largely determine the quality and performance of the whole.
A global classification divides the passive components into:
- Dissipative component - which dissipates active electricity and transforms it into heat in an irreversible process; they are called resistors. They are characterized by electrical resistance measured in ohms.
The same category includes photoresistors, thermistors, varistors and magnetoresistors in which the size of the electrical resistance is dependent on the action of physical factors (light, temperature, applied voltage, magnetic induction).
- Reactive components - they can be in two states: energy receiver that charges and keeps the stored energy and energy generator that debits the energy in the external circuit. Reactive energy flows in both directions. The reactive components store energy either in the electric field (at the capacitor) or in the magnetic field (at the coil). The capacitor is characterized by the electrical capacity measured in Farad. The coil is characterized by the magnetic inductance measured in Henry.
Real passive components
Real passive components are characterized simultaneously by all these sizes. So, a real resistor it will have at the same time an electrical capacity but also an inductor which are in this case parasitic quantities (their effect is manifested at high frequencies).
A capacitor will have, in addition to capacity, a resistance of losses and a parasitic inductance. It is mandatory that any passive component be analyzed and characterized before being used in circuits.
They will study some sizes characteristic of passive components to understand the complexity of their operation and use in circuits.
- Study of the dispersion of the nominal values of the passive components
- Measurement of the temperature coefficient for passive components
- Thermostat for studying the operation of electronic components at temperature variation
- Measurement of large capacities by the method of constant load current