Getting Started with PCB Design: Placing Components in Circuit Schematics

Embarking on PCB design involves the initial step of placing components in the circuit schematic. Here’s a systematic approach to assist you in positioning transistors, particularly Q1 and Q2, within the schematic diagram.

1. View the Entire Schematic

• Select **View >> Fit Document** to ensure the schematic is displayed in full-screen mode for a comprehensive view of the workspace.

2. Open the Library Panel

• Use the **Libraries** shortcut key to access the library panel where you can search and select necessary components.

3. Select the Appropriate Library

• For BJT components like Q1 and Q2, choose **Miscellaneous Devices.IntLib** from the library drop-down menu to activate the relevant component library.

4. Use Filter to Search Components

• Utilize the **filter** feature by setting it to *3904* to narrow down the selection to components containing “3904” for quicker search results.

5. Place the Transistor (2N3904)

• Locate the **2N3904** transistor, select it, and click **Place** to position it on the schematic.

6. Set Component Properties Before Placement

• Configure the component’s properties by pressing **TAB** with the transistor symbol attached to the cursor. Adjust parameters like footprint and values before final placement.

By following these steps meticulously, you can ensure precise component placement and configuration, laying a solid groundwork for a well-structured PCB design.

Step-by-Step PCB Component Placement and Configuration in Altium Designer

1. Set Component Designator

• In the Properties dialog box, assign **Q1** as the **Designator** for the first transistor.
• Ensure the correct component package (**TO-92A**) is selected and that the associated simulation model is available in the library.
• Click **OK** after verifying the settings.

2. Place the First Transistor

• Position the first transistor near the center-left area of the schematic and click or press **ENTER** to place it.

3. Duplicate the Transistor (Q2)

• Altium Designer automatically manages duplicate component names by adding a suffix like **Q2**.
• Place the second transistor (Q2) without the need to edit its properties again.

4. Adjust Component Orientation

• If Q2 requires a mirrored orientation, press **X** to mirror it horizontally.

5. Precisely Place Q2

• Align Q2 accurately by moving it to the right of Q1 and using **PAGE UP** to zoom in for better alignment.
• Press **ENTER** to place Q2.

6. Continue with Additional Transistor Placement

• Altium Designer facilitates placing multiple transistors sequentially. Follow the same process for each transistor.
• Exit component placement mode by pressing **ESC** or right-clicking to reset the cursor.

Placing Resistors

1. Load Resistor Library

• Access the **Miscellaneous Devices.IntLib** library and filter components with **res1**.

2. Select and Place Resistor R1

• Click on **Res1** to select the resistor and set the **Designator** to **R1** in the properties dialog.

Placing Components in Altium Designer

– Confirming Package Model and Setting Resistor Value

• Confirm that the AXIAL-0.3 package model is included, and set the resistor value to 100k.

– Adjusting Resistor Properties

• Disable the Visible option for the Value parameter as no simulation is needed.
• Rotate the resistor 90° by pressing the Spacebar to align it correctly.
• Place the resistor on top of Q1 and press ENTER to complete placement.

Placing Additional Resistors

• For R2, follow the same process, placing it on top of Q2. The designator will automatically be updated to R2.
• Set R3 and R4 to 1k. Use the TAB key to adjust the Comment field and disable the Visible option for Value.
• Position R3 and R4 as needed and exit placement mode with ESC or by right-clicking.

Placing Capacitors

Selecting and Editing Capacitor Properties

• In the Miscellaneous Devices.IntLib library, set the filter to cap to find the capacitor components.
• Click on CAP to select the capacitor and attach it to the cursor.
• Press the TAB key to open the properties dialog. Set the Designator to C1, the Comment to 20n, and disable the Value option since simulation is not required.
• Select RAD-0.3 as the PCB package and click OK.

Placing the Capacitor

• Place the capacitor in the schematic, then exit placement mode by pressing ESC or right-clicking.

Placing the Connector

Selecting and Setting Connector Properties

• Open the Miscellaneous Connectors.IntLib library, filter components by entering 2 (for two-row connectors).
• Click on Header 2 to select the connector, then click PLACE.
• Press TAB to open the properties dialog. Set the Designator to Y1, disable the Visible option, and select HDR1X2 for the PCB package.
• Click OK to confirm.

Adjusting Connector Orientation and Placement

• Before placement, press the X key to rotate the connector vertically.
• Place the connector at the desired location, then exit placement mode.

Final Steps

Saving Your Work and Connecting Component Pins

• Once all components are placed, navigate to File >> Save to preserve your schematic.
• Start connecting component pins, ensuring proper positioning for efficient layout creation.

By following these steps, the component placement process in Altium Designer is streamlined, leading to an efficient schematic creation process. Always verify component properties and orientations before finalizing your layout.