Section 2.4: Circuit Diagrams: Putting It All Together #
By now, you’ve gotten to know a lot of different components—resistors, capacitors, transistors, and more. You’ve seen their symbols sprinkled throughout earlier sections, and hopefully, they’re starting to feel familiar. Now it’s time to gather everything in one place and focus on how these symbols are used in circuit diagrams.
Key Information: A schematic is an electrical wiring diagram that uses standard component symbols. The most important thing to remember is that schematics show component connections accurately.
Think of a schematic as a map for electronics. Instead of using pictures of actual parts, it uses standard symbols to show how components connect. Once you know how to read them, circuit diagrams are your key to understanding any electronic device, no matter how complicated.
Essential Components and Their Symbols #
Let’s review the key components you’ll encounter in circuit diagrams. Pay special attention to how they control or affect current flow in a circuit.
Basic Components #
| Component | Description | Symbol |
|---|---|---|
| Resistor | That familiar zig-zag line represents a component that controls current flow. You’ll see these everywhere in circuits. |  |
| Variable Resistor (Potentiometer) | Like a regular resistor, but with an arrow showing you can adjust its value. |  |
| Capacitor | Those parallel lines store electrical energy. You’ll see both polarized (with a curved line) and non-polarized versions. |  |
| Inductor | A coil of wire which stores energy in a magnetic field |  |
| Transformer | Two coils side by side show energy transfer between circuits. |  |
| Variable Inductor | A coil with an arrow showing you can adjust its value. |  |
Active Components #
| Component | Description | Symbol |
|---|---|---|
| Transistor | These workhorses control current flow and provide amplification. The arrow shows current direction. | 
|
| Diode | As seen in the Section 2.2, the arrow points towards negative (cathode) |  |
| LED (Light Emitting Diode) | Like a regular diode but with arrows showing it emits light. | 
|
Power and Indicators #
| Component | Description | Symbol |
|---|---|---|
| Battery | Long and short lines show positive and negative terminals. | 
|
| Lamp | A light bulb, or lamp. | 
|
| Antenna | A line with smaller lines at an angle represents an antenna, where signals enter or leave the circuit. |  |
Reading Circuit Diagrams #
When looking at a schematic:
- Start at the power source (usually a battery)
- Follow the connections between components
- Notice how components are labeled (R1, C1, etc.)
- Pay attention to component values when shown
Remember: While schematics might look complicated at first, they’re just maps showing how components connect. With practice, you’ll be reading them like a pro!
Practical Tips #
- Look for common patterns in circuits
- Pay attention to component labels
- Follow the current path from power source through components
- Remember that connection points are shown by dots where lines meet
As a Technician Class operator you won’t need to know this stuff in depth, but there are a few questions you might see on the exam which require you to identify a component by its symbol – make sure you look over them carefully so you know what to look for!
Schematic
