Transcript Building Curcuits From Schematics

Electric Curcuits and
Measurements

Basic Electrical
components and their
functions

Measurements of electrical
circuits characteristics
- Multimeter
- Oscilloscope
- Function Generator
Building Curcuits
From Schematics
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Basic Electrical components:
- resistors
- capacitors
- Potentiometers
- Capacitors
- Diodes
- LED’s (light emitting diodes)
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Electronic Circuit is a collection of
components that electricity is driven
through to accomplish a task
wire has no resistance
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Building Curcuits
From Schematics
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breadboard is a
plastic matrix with
holes
Power supply and
ground
Leads of el.
components are
inserted into the
holes
Bus strips holes are
electrically
connected in vertical
direction (used for
power distribution)
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terminal strips holes
are electrically
connected in
horizontal direction
(5 holes series only)
Resistors
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Resistor – dissipative element that converts
electrical energy into heat.
Ohm’s law V=IR
Defined by voltage-current characteristics –
slop of the voltage-current curve:
Wire-lead resistor’s value and precision are
coded with four colored bands
Bands: a – tens digit, b – ones digit, c- power of 10, tol – tolerance of
uncertainty
Resistors
R  ab 10c  tolerance%
Example:
a = green, b=brown, c= red, and t= tol = gold
Range of possible resistance values:
R  51 102 Ohm  5% 
 5100  (0.05 5100)Ohm
4800Ohm  R  5300Ohm
Resistors in series:
R=R1+R2
Resistors in parallel:
R=R1*R2/(R1+R2)
Resistors
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-
Kirhchoff’s Laws:
Sum of voltages around a closed
loop or path is zero:
N
V
i 1
i
0
- Sum of currents flowing into a
surface or node is zero:
N
I
i 1
i
0
Series Resistors
Curcuit
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Voltage divider
- voltage Vs divides between each
resistor
- creates different reference voltages in a
circuit (having single output supply)
V R1 
RV
R
i
eq
s
Resistors/Potentiom
eter
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Potentiometer or pot – variable resistor
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Provide range of resistance values
controlled by mechanical screw, knob or
linear slide:
Capacitor
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Capacitor is a passive element that stores
energy in the form of an electric field (as a
result of a separation electric charge)
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Consists of conducted plates separated by
dielectric material
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Capacitance (C) units: farads
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Dielectric material is an insulator that
increases the capacitance as a result of
permanent or induced electric dipoles in
the material
Capacitor
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Capacitors in parallel
C = C1+C2
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Capacitors in series:
C = C1*C2/(C1+C2)
Diodes
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Diode is a pn-junction that passes current
in only one direction (or rectifier)
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Analog to check valve
Diodes
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Optoelectronic Diodes or Light Emitting
Diodes (LEDs) – emit photons
- positive lead (anode) is longer
Measurements

Multimeter (measurements
in DC circuits)
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Oscilloscope
(measurements in AC/DC
circuits
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Function generator
(power supply for generation of
voltage waveform)
Measurements/Multi
meters
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Multimeter
(measurements in DC
circuits)
-Only measure resistance when
power to the circuit is OFF ;
- during resistance or voltage
measurements multimeter probes
are place in parallel to the circuit;
- in current measurement the
probes need to be placed in series
(you need to disconnect the el.
component)
Measurements/
Oscilloscope
Oscilloscope – voltage-measuring
instrument, capable of recording high
frequency signals (chapter 3.5.4, p. 10 of manual)
Measurements/
Oscilloscope
Basic concepts (see course web-page)
 Probe
 Self-calibration
 Triggering
- determines proper acquirement of data
- options (source,
coupling etc.)
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Acquiring Data
Scaling and Positioning Waveforms
- vertical, horizontal
- aliasing etc…
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Autoset
Math functions
Etc…
Measurements/
Oscilloscope/Triggering
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To ensure that a recording of the signal
from the transducer is made at a correct
time (or synchronized) triggering is used
(see details in manual, p.10)
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Triggering synchronizes an oscilloscope
with the event (signal capturing)
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Sources of trigger signals:
- input channel (commonly used)
- AC Line
- External
Input channel triggering:
- uses input signal, activate internal
sawtooth generator and initiate
synchronization;
- frequency of the generator is adjusted
to the one of the input signal
- signal trace appears stationary on the
screen
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Measurements/
Oscilloscope/Triggering
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Auto triggering: depends on time-base
(controlled by SEC/DIV knob)
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Time base (p.16, manual) – controls how
often the values (of a signal) are digitized
Measurements/
Oscilloscope/Scaling
and positioning waveforms
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You can change size, scale and position of the
wave form on the display (vertically and
horizontally, using SEC/DIV knob)
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Aliasing – occurs when the oscilloscope does
not sample signal fast enough (check it using
SEC/DIV knob)
Measurements/
Oscilloscope/Menu
Control buttons
SAVE/RECALL – restore factory settings
Measurements/
Oscilloscope
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Taking measurements
(p.37-39,
manual)
- using autoset (when signal amplitude or
frequency unknown)
- automatic measurements
- two signals measurements: