Drawings

1. Drawings

2. The Drawing Set • Design Drawings • System Block Diagram • Circuit Design Sketch • Packaging Plan • Working Schematic • Breadboard Drawing • PC Board Design Layout • PC Board Artwork Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 76)

3. The Drawing Set (Continued) • PC Board Fabrication Drawing • PC Assembly Drawing • Sheet Metal Drawing • Wiring Diagram • Final Packaging Drawing Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 76)

4. The Design Drawings

5. System Block Diagram Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 60)

6. Circuit Design Sketch Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 61)

7. Packing Plan Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 61)

8. Introduction to Schematics

9. ANSI and IEEE • Define accepted practices and symbols for schematic and electrical diagrams. • Most CAD program conform to these standards. • Schematic symbols are covered by (ANSI Y32.2)

10. Standard Symbols

11. Resistor - R Switch - S Transformer – T Transistor - Q IC – U Crystal – Y Capacitor – C Diode – D Fuse – F Relay – K Coil/Inductor – L Microphone – MK Designators Protel places the proper designator on all parts for you.

12. Layout Considerations • If a schematic is large, split the schematic into functional sections, each on a separate page, making sure to properly label connection ports. • Layout should be arrange to develop from the top to bottom and from left to right as the signal flows

13. Layout Considerations (continued) • Voltages should be clearly marked. • Ground symbols should always be drawn below the line.

14. Proper Signal Flow Example INPUTS Outputs Higher Potential Lower Potential

15. Layout Considerations (continued) • All connecting lines are either vertical or horizontal. • There are a few exceptions: • Bus connections • Flip flops • Bridge Rectifiers

16. Layout Considerations (continued) • Similar circuits should be drawn uniformly. • Common circuits should be drawn according to accepted conventions.

17. Example Non-Standard Schematic

18. Example Non-Standard Schematic Standard Schematic

19. Layout Considerations (continued) • When identifying values of resistors, capacitors or inductors: • Use proper unit prefixes • p for Pico • u for Micro • m for milli • K for Kilo • M for Mega • For resistors, ohms is implied and should not be used.

20. Layout Considerations (continued) • Parts should be numbered starting from the upper left hand side of the schematic to the lower right hand side. • This method makes it very easy to locate parts on the schematic.

21. Part Numbering Example

22. Layout Considerations (continued) • Short dashed lines indicate mechanical interconnects. • Each schematic should have a filled in title block.

23. Layout Considerations (continued) • Lines should be drawn with the minimum of crossovers and joggles. • Junctions of 3 or more wires should be marked with a dot to indicate a connection. No dot, no connection. • Lines between components should take the shortest path.

24. Example of Crossover and Joggles

25. Connections and Dots

26. What’s Wrong With This Picture?

27. Improved Schematic