CHAPTER 8ELECTRICAL ELECTRONIC DRAWINGS
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.
Objectives:
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.
Introduction
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)
Resistori) 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.
Diodei) 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.
Aeriali) 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°.
Earthi) 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)
Resistori) 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.
Methods of Drawing and Designing Circuits A few things must be emphasized in designing circuits i.e.
I) component arrangementii) wiring patternIii) adjustment of component's sizeiv) space while designing schematic diagram
Basic of Electronic Circuits
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
IntroductionA 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 TechniqueExample 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.
● Block diagram is a diagram of a system
●The principal parts or functions represented by block and connected by lines which is shows the relationships of the blocks
●Heavily used in engineering world inI) Hardware designii) Software designiii) Process flow diagrams
Block Diagram
Example of block diagram figure which usually used in drawing
Block Diagram
Block Diagram
Block Diagram
● The block diagram is labeled by stages of circuit, wave signal at input and output source.
● If block used more than 1, the blocks might be arrange in series or parallel. Each block is connected by straight lines followed the schematic circuit.
Example 1: Amplifier schematic diagram
Block diagram of amplifier
Exercise 1: Draw a block diagram of the circuit given
Introduction to Printed Circuit Board (PCB)
A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a nonconductive substrate.
Example of PCB
Methods of PCB Drawing
Step 1: Determine the PCB size and circuit size.
Step 2 : Draft the circuit. The component's arrangement should be neatly arrange.
Step 3: Draw the pattern strips.
Step 4: The drawn pattern strip being seen reversely and transferred to PCB
Example 1:
Solution: 1) Arrange the components position.
2) Design the conductive path.
3) Draw the conductive path on PCB. Label all the poles.
Example 2:
Solution:
Exercise 1: Draw the PCB layout of the schematic given.
Exercise 2: Draw the PCB layout of the schmitt trigger schematic.
Assignment 3:
Draw sets of drawing of torchlight @ flash light. Please submit on Friday 29/10/2010 before 5.00pm.