CONVERTING A SCHEMATIC TO A LAYOUT DIAGRAM


Have you ever looked at a schematic and thought "I'd like to build that" but been unable to since no constructional information was given.
This page will help you to overcome this by showing how to design a layout diagram from the schematic.

 



The layout diagram may not appear to look much like the schematic diagram since the actual components such as resistors, capacitors transistors etc will vary  in size, shape,  colour and position.

Look at the schematic.

e = emitter    b=base    c= collector

One end of R1 R2 and C1 are joined to transistor TR1 base.
TR1 collector is joined to one end of R3 and C2.
The other end of R3 is joined to the top end of R1 and goes to the 12 volt battery positive.
The positive end of C1 not connected.
The negative end of C2 is not connected.
One end of  C3 and R4 are joined to the emitter of TR1.
The other ends  of C3, R4 and R2 go to the negative terminal of the battery.

The simplest method of producing a layout diagram is to make a drawing where the leads of the components are joined together by blobs.
These blobs represents soldered junctions as  shown below.
For example one end of R1 R2 C1 and the base of the transistor are joined together by a solder blob.
 


 
 
This technique is OK for testing a prototype but is very untidy and all the bare wires are likely to produce short circuits.
Also it is difficult to join several components with a single solder blob.

A neater method is to use STRIPBOARD.

One side of the board has rows of holes into which the component leads are inserted


On the other side of the board are copper strips (tracks) to which the leads are soldered.

The copper strips are soldered where the leads poke through thus joining the leads together.

Tracks can be cut to isolate parts of the track.

Look at the drawing below.
 


One end of R1 R2 and C1 are joined to transistor TR1 base by track C.
TR1 collector is joined to one end of R3 and C2 by track B.
The other end of R3 is joined to the top end of R1  by track A and goes to the 12 volt battery positive.
The negative end of C2 is not connected.
The positive end of C1 is not connected.
One end of  C3 and R4 are joined to the emitter of TR1 by track D.
The other ends  of C3,R2 and R4 go to the zero volts (negative) terminal of the battery via track E.

The tracks under C1 and C2 are cut to avoid both ends of the capacitors being joined to each other
This could be avoided by mounting C1 and C2 at right angles to the tracks..

There is another page on this website giving more information on using  Stripboard .
 


 
The following diagram shows the how to produce PRINTED CIRCUIT (PCB) layout diagrams.
Components are mounted on one side of the board. Their leads pass through holes in the board and are soldered to copper pads and tracks on the other side of the board.

 
 


In the diagram both sides are shown together for easier explanation.
See how one end of the components R1 R2 C1 and the base of TR1 are joined by the copper track as shown in the other methods.

R3 C2 and TR1 collector are joined.
etc

There are  other pages on this website which describe  PCB production .


 
A layout that beginners often find difficult is the BRIDGE RECTIFIER shown below.


The circuit has been redrawn below but is exactly the same circuit.


Now it is easier to see how the layout drawing is to be made.

Here is a PCB version of it. Both component and copper sides are shown for clarity.


 
Now look at this astable flasher schematic.
First we draw TR1 and its associated components.
Then add TR2 and its components.

Note how the tracks have been cut in three places to avoid parts of TR1 layout being joined to TR2 layout.
Now the two capacitors are added.

They have been fitted at right angles to the tracks to save space.

Four wire links route the capacitors to the correct points on the layout.

Another cut in a track has been made. 


 
Now study the  2 WATT AMPLIFIER schematic and layout.

 

Copyright Graham Knott 2004