Lesson 4 Flashcards
these are the three basic passive elements
used in electrical circuits, either as individual devices or in combination. These elements are used as loads, delays, and current limiting devices.
Resistors, capacitors, and inductors.
are used as dc blocking devices, in level shifting, integrating, differentiating, filters,
frequency determination, selection, and delay circuits.
Capacitors
can be extended to cover analog meter movements, relays, audio to electrical conversion,
electrical to audio conversion, and electromagnetic devices. They are also the basis
for transformers and motors.
Inductive devices
are extensively used in ac circuits for frequency
selection, noise suppression, and so forth, and are always present as
parasitic components, limiting signal response and introducing
unwanted delays. These components also cause phase shift between
voltages and currents, which has to be taken into account when
evaluating the performance of ac circuits.
- Voltage Step Input
- Time Constants
- Sine Wave Inputs
Passive components
can be either passive or active (using amplifiers), and are divided into the
following types.
Filters
Passive networks using _______and _______are extensively used [2], and
sometimes small ______are used in instrumentation circuits for filtering
out noise, frequency selection, and frequency rejection, and so forth.
resistor
capacitor
inductors
RC Filters that Allows high frequencies to pass but blocks low frequencies;
High-pass.
RC Filters that Allows Low frequencies to pass but blocks high frequencies;
Low-pass.
RC Filter that Allows a specific range of frequencies to pass;
Band-pass.
RC Filter that Blocks a specific range of frequencies;
Band reject.
Form of band reject filter, but with a sharper response characteristic.
Twin – T.
Resistor temperature compensation can be achieved in
voltage divider circuits or bridge circuits.
circuits are used to convert small changes in impedance into voltages. These voltages are referenced to zero, so that the signals can be amplified to give high sensitivity to impedance changes.
Bridge circuits
The two resistive elements R1 and R2 in a strain gauge sensor can be connected in
series to form a _________,
voltage divider
The elements are driven
from a supply, Vs . Since the temperature coefficient of resistance is the same in
both elements, the voltage at the junction of the elements, VR, is independent of
temperature, and is given by:
Voltage Dividers
the simplest and most common bridge network is the_______.
The basic bridge is modified for use in many other specific
applications. In. the basic bridge four resistors are connected
DC Wheatstone
bridge.
in the form of a diamond with the supply and measuring instruments connected across the bridge as shown. When all the
resistors are equal the bridge is balanced; that is, the bridge voltage at A and C are equal (E/2), and the voltmeter reads
zero. Making one of the resistors a variable resistor the bridge can be balanced.
The voltage at point C referenced to D = E × R4/(R3 + R4)
The voltage at point A referenced to D = E × R2/(R1 + R2)
The voltage (V) between A and C = E R4/(R3 + R4) − E R2/(R1 + R2)
When the bridge is balanced V = 0,
and R3R2 = R1R4
dc Bridge Circuits
