Rules for drawing circuit diagrams

1.   How to draw your circuit

1. To change the orientation of an image in the prototype area, click on it.

2. To add a non-wire component, find its image in the scrollable ``prototype'' area to the left of the applet. Ensure that the orientation of the prototype component is the one you want (see above if it's not). Then click on where you want the left end (if horizontal) or the top end (if vertical) to be.

3. A second click removes the component.

4. To add a wire, select the ``wire'' image in the prototype area. Then click in the main circuit grid area on each ``end'' in turn. The points you click on will be joined up.

5. To remove a wire, select ``wire'' from the prototype area, and click on the end points.

6. You will be asked for values for all component values when you press the ``simulate'' button.

7. To change a value after a simulation, delete the component and add it again. This usually takes only two mouse clicks.

2.   Placement rules

1. Components and wires exist in two orientations - horizontal or vertical - except for op-amps, which may only be horizontal.

2. Not more than 3 components or wires may terminate at a point.

3. No two components or wires may overlap one another, with the single exception that a horizontal wire and a vertical wire are allowed to cross one another.

4. Non-wire components have fixed lengths (8 units on the screen). Wires may have any integer length greater than zero.

3.   Node numbers

1. The program computes ``node numbers'' so that it can refer to points in the circuit. These will be displayed on the circuit diagram when you press ``simulate''.

2. The ``ground rail'' (zero volts reference) is the lowest horizontal line in the circuit, just as in a typical hand-drawn circuit, and is always labelled with the node number 1.

4.   Temporary restrictions

1. Simulation fails if the circuit contains inductors and the frequency range includes 0 Hz.

2. You cannot join a component or wire to the middle of a previously-drawn wire. You have to delete the previously-drawn wire first, then add the new component or wire, then join up the dots again. Similarly, you cannot draw a wire through an existing node.

3. There is no help for you.   :-)