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CHAPTER 8
ELECTRICAL ELECTRONIC DRAWINGS
Objectives:
­ To understand the difference between electronic drawing and other practiced engineering drawing
­ To define the types of electronics drawing used in the industry
­ To understand standardized schematic symbols for electronic devices
­ To draw a schematic diagram using standardized schematic symbols
­ To identify different types of circuit board drawings.
Introduction
­ Several types of drawings are used only in electronic industry such as:­
­ block diagrams
­ wiring diagram
­ schematic diagrams
­ logic diagrams
­ printed circuit board drawings
­ Electronic drawings not drawn to any scale. Schematic, block digram and wiring drawings define how electronic devices work together. Electronics Symbol
Graphics Standards ASA and DIN Symbols
Electronic graphic symbols can be drawn according to international standards that have been established and recognized by the International Electrotechnical Commission i.e
i) ASA or ANSI Standards (American National Standrad Institute)
ii) DIN Standards ( Data International Standard)
iii) British Standards
­ not approved schematic
Methods of Drawing Symbols (ANSI Standards)
Resistor
i) Draw guidelines for the correct ratio when drawing resistor symbols.
ii) Draw inclined lines with angle 60°.
iii) Draw inclined lines on opposite side with angle 60°.
iv) Draw a straight line to complete a graphic symbol.
Diode
i) Draw guidelines for the correct ratio when drawing diode symbols.
ii) Draw a vertical line for cathode element position.
Iii) Draw a sloping line bottom vertical line which touches the cathode element.
iv) Draw sloping line on other side.
v) Draw horizontal line to complete the symbol.
Aerial
i) Draw guidelines for the correct ratio when drawing aerial symbol.
ii) Draw a vertical line as shown in figure below.
Iii) Draw a sloping line on top of vertical line with angle 60°.
iv) Draw a sloping line on other side with angle 60°.
Earth
i) Draw guidelines for the correct ratio when drawing earth symbol.
ii) Draw a vertical line as shown in figure below.
Iii) Draw a draft line on on both side at angle 60°.
iv) Draw parallel lines horizontally by referring on guidance line.
v) A complete drawing of Earth symbol.
Methods of Drawing Symbols (DIN Standards)
Resistor
i) Draw guidelines for the correct ratio when drawing resistor symbols.
ii) Draw horizontal lines upper and lower inside guidelines box .
iii) Draw vertical lines to join the horizontal lines.
iv) A complete resistor symbol.
** for potentiometer, draw an inclined line (45°) across the graphic symbol.
Basic of Electronic Circuits
Methods of Drawing and Designing Circuits
­ A few things must be emphasized in designing circuits i.e.
I) component arrangement
ii) wiring pattern
Iii) adjustment of component's size
iv) space while designing schematic diagram
Circuit Arrangement
­ All components symbol should be neatly arranged and organized. ­ types of drawing arrows
● Arrow is to indicate the direction of flow signals in a circuit
●There are two types of drawing arrows
i)
ii) ­ Example of parallel circuit
Designing Schematic Circuit
Introduction
A schematic is a diagram that represents the elements of a system using abstract, graphic symbols rather than realistic pictures. A schematic usually omits all details that are not relevant to the information the schematic.
Design Technique
Example 1: From the stripboard layout, design the schematic circuit.
I) list all the components in the circuit and identify their symbols
ii) draft the circuit layout
Iii) Draft and arrange symbols position on the layout. The arrangement must be balance.
iv) Draw the schematic circuit.
Exercise 1: From the stripboard layout, design the schematic circuit.