EagleCAD Part 1: Create Schematic
In this example we will go step by step, creating a schematic in EagleCAD for a 10-watt audio amplifier based on the TDA2003 chip.
1. Open Eagle
2. File > New >Project
3. Name the project folder: AudioAmp10W.
4. Right click on the folder, hover over New, and create a new schematic.
5. In the schematic window, save this file (.sch) as amp10W_01
6. Add the first component, the TDA2003 chip:
a. Click on the Add Component icon.
b. In the search field, type TDA2003* (Note that inclusion of the asterix at the end of the component name is essential, and should be standard for all searches in Eagle). When you click on TDA2003V AUDIO AMPLIFIER, the schematic symbol and the pcb symbol for TDA2003V show up on the right.
c. Select the TDA2003 component and click OK.
d. Drag the component to the middle of the schematic.
e. Press ESC to add the next component.
7. For the next component, we’ll add three two-position screw terminal, so search for screw*, select the Wago-102 Wago Screw Clamp, and click OK. Click the mouse at three positions on the schematic; this creates three copies of the component. Press ESC to add the next component.
8. Next, we’ll name each of the pins on the screw clamps:
a. Right click on a screw clamp, and choose Name. Name it PWR.
b. Do the same for the other two screw clamps, naming them A-IN and A-OUT.
9. Next we’ll create symbols for the power supply and ground:
a. For the power supply, click Add Component and search for +12V*; choose the one under supply2; click OK. Click on the schematic to create that symbol. Click ESC twice.
b. Right click on the symbol, and select Copy. Move the cursor and left click, producing another copy of the symbol.
c. For the ground, do the same thing after searching for GND.
10. Next, we’ll search for capacitors and resistors by typing capacitor* and resistor*.
There are two types of capacitor: polarized and non-polarized. The picture belows shows the symbol for polarized capacitor.
and this is the symbol for non-polarized capacitor
Symbol for resistor:
11. Add poteniometer
12. Finally to connect components together, we select the wire
Draw a line to connect two components together. After that, click on Move 
, and move the component around, if the trace moves with the component that means the components are connected. . Press escape when done to start drawing another line
