Draw a circuit diagram by replacing every physical component with its recognized standard component symbol, then connect the symbols with straight lines that show the circuit's electrical relationships. The diagram must communicate function and connectivity, not the components' physical positions.
Begin by identifying the required input, processing, control and output components. Place the power supply first, arrange the remaining components in a logical signal or current path, and then add connections.
Follow these conventions:
| Circuit feature | Correct convention | Check to make |
|---|---|---|
| Series connection | Place components consecutively on one current path | The same current can pass through each component |
| Parallel connection | Create branches connected across the same two nodes | Each branch receives the same potential difference |
| Junction | Mark the joined conductors with a clear node | All lines meeting at the node are electrically connected |
| Crossing conductors | Use the accepted no-connection convention | Do not imply a junction where none exists |
| Polarized component | Use the correct symbol and orientation | Check batteries, diodes, LEDs and electrolytic capacitors |
| Component value | Label the symbol clearly | Include values such as or |
For example, an LED indicator circuit may contain a battery, switch, current-limiting resistor and LED connected in series. The resistor must appear in the same current path as the LED, and the LED must have the correct polarity. Trace the complete path from the positive supply terminal through every component and back to the negative terminal to confirm that the circuit can operate.
A common misconception is that a circuit diagram should resemble the physical layout of the finished product. That is a wiring or layout representation; a circuit diagram instead shows electrical function through standardized symbols and connections.
In IB Design Technology B3.4, a draw task requires an accurate, clearly labelled representation. Examiners look for recognizable symbols, correct series and parallel relationships, unambiguous junctions, appropriate polarity and relevant component values. Always perform a final node-by-node check before finishing.