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Electric Curcuits and Measurements

Electric Curcuits and Measurements. Basic Electrical components and their functions Measurements of electrical circuits characteristics - Multimeter - Oscilloscope - Function Generator. Building Curcuits From Schematics. Basic Electrical components:

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Electric Curcuits and Measurements

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  1. Electric Curcuits and Measurements • Basic Electrical components and their functions • Measurements of electrical circuits characteristics - Multimeter - Oscilloscope - Function Generator

  2. Building Curcuits From Schematics • Basic Electrical components: - resistors - capacitors - Potentiometers - Capacitors - Diodes - LED’s (light emitting diodes) • Electronic Circuit is a collection of components that electricity is driven through to accomplish a task • wire has no resistance

  3. Building Curcuits From Schematics • 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) • terminal strips holes are electrically connected in horizontal direction (5 holes series only)

  4. Resistors • 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

  5. Resistors Example: a = green, b=brown, c= red, and t= tol = gold Range of possible resistance values: Resistors in series: R=R1+R2 Resistors in parallel: R=R1*R2/(R1+R2)

  6. Resistors • Kirhchoff’s Laws: - Sum of voltages around a closed loop or path is zero: - Sum of currents flowing into a surface or node is zero:

  7. Series Resistors Curcuit • Voltage divider - voltage Vs divides between each resistor - creates different reference voltages in a circuit (having single output supply)

  8. Resistors/Potentiometer • Potentiometer or pot – variable resistor • Provide range of resistance values controlled by mechanical screw, knob or linear slide:

  9. Capacitor • Capacitor is a passive element that stores energy in the form of an electric field (as a result of a separation electric charge) • Consists of conducted plates separated by dielectric material • Capacitance (C) units: farads • Dielectric material is an insulator that increases the capacitance as a result of permanent or induced electric dipoles in the material

  10. Capacitor • Capacitors in parallel C = C1+C2 • Capacitors in series: C = C1*C2/(C1+C2)

  11. Diodes • Diode is a pn-junction that passes current in only one direction (or rectifier) • Analog to check valve

  12. Diodes • Optoelectronic Diodes or Light Emitting Diodes (LEDs) – emit photons - positive lead (anode) is longer

  13. Measurements • Multimeter (measurements in DC circuits) • Oscilloscope (measurements in AC/DC circuits • Function generator (power supply for generation of voltage waveform)

  14. Measurements/Multimeters • 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)

  15. Measurements/ Oscilloscope Oscilloscope – voltage-measuring instrument, capable of recording high frequency signals (chapter 3.5.4, p. 10 of manual)

  16. Measurements/ Oscilloscope Basic concepts(see course web-page) • Probe • Self-calibration • Triggering - determines proper acquirement of data - options (source, coupling etc.) • Acquiring Data • Scaling and Positioning Waveforms - vertical, horizontal - aliasing etc… • Autoset • Math functions • Etc…

  17. Measurements/ Oscilloscope/Triggering • 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) • Triggering synchronizes an oscilloscope with the event (signal capturing) • 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

  18. Measurements/ Oscilloscope/Triggering • Auto triggering: depends on time-base (controlled by SEC/DIV knob) • Time base (p.16, manual) – controls how often the values (of a signal) are digitized

  19. Measurements/ Oscilloscope/Scaling and positioning waveforms • You can change size, scale and position of the wave form on the display (vertically and horizontally, using SEC/DIV knob) • Aliasing – occurs when the oscilloscope does not sample signal fast enough (check it using SEC/DIV knob)

  20. Measurements/ Oscilloscope/Menu Control buttons SAVE/RECALL – restore factory settings

  21. Measurements/ Oscilloscope • Taking measurements(p.37-39, manual) - using autoset (when signal amplitude or frequency unknown) - automatic measurements - two signals measurements:

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