Communication Signals

1. Fox Valley Technical College Appleton, WI Communication Signals Basic Circuits G Herlache

2. Basic Circuit Parts • Power Supply (e.g. battery) • Circuit Protection (e.g. fuse, circuit breaker) • Control (e.g. switch) • Load (e.g. lamp) • Conductors G Herlache

3. Pictorial Diagram of A Simple Electric Circuit Current Flow Wire Conductor Voltage Source - + Lamps Battery G Herlache

4. A Schematic Diagram for the Simple Circuit Battery Or DC Voltage Supply PL2 VS PL1 Lamps G Herlache

5. Hardware Pictorial and Schematic of a Closed CircuitUsing a SPST switch for control Off On Closed Switch - + V I - + Closed Circuit Path => Current Flow G Herlache

6. Hardware Pictorial and Schematic of an Open CircuitUsing a SPST switch for control Off On Open Switch - + V - + Open Circuit Path => NO Current Flow G Herlache

7. Example: Pictorial of a SPDT switch controlling two lamps 1 Lamp 1 2 + Switch - Lamp 2 G Herlache

8. Example: Schematic of a SPDT switch controlling two lamps 1 1 SW SW Lamp 1 Lamp 1 2 2 - + - + V V Lamp 2 Lamp 2 G Herlache

9. Switch Symbols NCPB NOPB SPST-NC SPDT Break-Make PB SPST-NO Single-pole rotary (6-position) DPST DPDT G Herlache

10. Typical Mechanical Switches G Herlache

11. Construction View of a Typical Toggle Switch G Herlache

12. Chassis Ground DC Ground AC Ground Symbols for Ground G Herlache

13. A Simple Circuit Schematic Using Ground Symbols I - + 12 V 0 V Ground Symbol G Herlache

14. V A Ω T Schematic Symbols Introduced So Far Circuit Breaker Fuse Grounds Rheostat Potentio- meter Battery Resistor Lamps SPST-NO SPST-NC NOPB NCPB SPDT Break-Make PB DPST Ammeter Voltmeter Ohmmeter Photo Resistor Thermistor DPDT Rotary Switch G Herlache

15. Series Circuit IS + V3 − +V1− +V2− IS VS + V4 − +V6− +V5− IS • One path for current. So all components have the same current through them. • But components have different voltages consistent with the voltage – current relationship for each type of component. G Herlache

16. Parallel Circuit I1 I2 I3 I4 I5 + VS − + VS − + VS − + VS − + VS − VS • One voltage source. So all components have the same voltage across them. • But the components have different currents consistent with the voltage – current relationship for each type of component. G Herlache

17. Series-Parallel Circuit VS Most circuits are a combination of series and parallel circuits. G Herlache

18. A node is a connection of a number of circuit components. • A complete node includes all components connected • together electrically Complete Node Partial Node Partial Node Circuit “Nodes” G Herlache

19. Specialized Electronics Training Basic Logic Circuits G Herlache

20. Basic Logic Circuits High = +VS = Logic 1 = True = On +VS High ? We don’t know Low = +0 Volts = Logic 0 = False = Off ? Low 0 • Different logic circuit families have different limits for: • Minimum voltage that can be called “high” • Maximum voltage that can be called “low” • There are different names that mean the same thing. G Herlache

21. Basic Logic Circuits +12V +12V VOut Next Circuit Normally Low (Logic 0) When the switch is open VOut is __?__ volts. When the switch is closed, VOut is __?__ volts. Add a subsequent circuit that supplies a little current through the resistor when the switch is open, and what happens to VOut? G Herlache

22. Lab Activity Logic with a Normally Open (NO) Switch +12V SW1 10KΩ VOut V 1KΩ Build the circuit initially without the 10KΩ resistor. What is VOut when SW1 is closed? _______________ What is VOut when SW1 is open? _______________ Add the 10KΩ resistor in parallel with SW1. Now what is VOut when SW1 is open? _____________ G Herlache

23. Basic Logic Circuits +12V +12V • Notice: • The switch is now a normally • closed. • The position of the resistor and • switch are reversed • Therefore: the normal state is still Low. VOut Next Circuit Normally Low (Logic 0) When the switch is open VOut is __?__ volts. When the switch is closed, VOut is __?__ volts. Add a subsequent circuit that absorbs a little current through the resistor when the switch is open, and what happens to VOut? G Herlache

24. Lab Activity Logic with a Normally Closed (NC) Switch +12V 1KΩ VOut V SW1 10KΩ Build the circuit initially without the 10KΩ resistor. What is VOut when SW1 is closed? _______________ What is VOut when SW1 is open? _______________ Add the 10KΩ resistor in parallel with SW1. Now what is VOut when SW1 is open? _____________ G Herlache

25. Lab Activity: N.O. Switch Logic(optional) SW1 SW2 SW2 SW1 VOut VOut 9VDC 9VDC R1 470Ω R1 470Ω D1 D1 AND Logic OR Logic G Herlache

26. Lab Activity: N.C. Switch Logic(optional) • NOTICE: • Series switchesare OR logic now! • Parallel switchesare AND logic now! 470Ω R1 470Ω VOut 9VDC 9VDC R1 D1 SW1 VOut SW2 SW1 D1 SW2 OR Logic AND Logic G Herlache

27. Logic with N.O. Push Buttons Normally High (Logic 1) Normally Low (Logic 0) AND Logic OR Logic +VS Closed 0V Open +V Closed +V Open 0V COM G Herlache

28. Logic with N.C. Push Buttons Normally Low (Logic 0) Normally High (Logic 1) OR Logic AND Logic +VS Closed 0V Open +V Closed +V Open 0V COM Notice the change here! G Herlache

29. Do not use these as logic circuits!!! • This circuit has four • output states: • Both switches open: • V1unconnected • V2unconnected • SW1 closed, SW2 open: • V1 = VS • V2unconnected • SW1 open, SW2 closed • V1unconnected • V2 = 0 Volts • Both switches closed • V1 = VS • V2 = 0 Volts This circuit has the same four output states: SW1 SW1 V1 V1 V2 V2 SW2 SW2 Unconnected outputs have unknown states.. These are not acceptable logic circuits! G Herlache