Design using CAD.


This tutorial is now complete. Please report any errors to Divinderjit Singh Chattrath

Designing transistor using SketchUp


The first step is to get the physical dimensions of the transistor BC547 which is available here.

The section, that we are interested in, is shown below.


 Let us now develop this component in SketchUp using this information.

There are two challenges in this model


 Let us make it...

Draw a circle of radius 250 mm so that the diameter of the circle is 500 mm. Now draw a line to make the flat face.


Select the minor area and the minor arc


 and delete them

 Using push-pull tool, pull the 2D shape upwards for 500 mm.  


make a vertical square on green axis (and blue axis as the other dimension). Find its midpoint and draw a circle of radius 250 mm.


Delete everything else in the square leaving the circle


Extrude it using push-pull tool to convert it into a cylinder

 select the cylinder

 Move this cylinder using move tool so that it is partially embedded in the curved surface of the transistor as shown below. The amount of the depth is determined by the depth of the notch you are trying to create.

 Not select everything using "ctrl+a" right click anywhere on the surface and select "Intersect Faces" followed by "With Model"

Now delete all parts of the cylinder and you will get your notch

Next we will make wire using the follow me tool. Use the tape measure tool to set up your guides. The side of the wire (or diameter) is 0.5 mm when scaled  by a factor of 100 it becomes 50 mm.

So we need three squares (or circles or squares with rounded edges) on the base of the transistor as shown in the figure below.

To achieve this, draw two guides on each side of the green axis at a distance of 25 mm from the origin. Then from red axis draw a guide at 25 mm and then another further on the same side at 50 mm. This will give you the center square. Make two more on either side of this square.

Now make lines as shown from center of each square. To make the wire all you have to do is to select the line, click the "follow me" tool and then click on the square at the base of that line.

 Finish you transistor!