The name EAGLE is an acronym, which stands for Easily Applicable Graphical Layout Editor. This software offers user friendly, powerful interface for PCB design, including Schematic Capture, Board Layout.
I think its good to get friendly with this software, since it will help you design, read and analize circuit schematics from simple ones to more complicated. You can search Youtube for some tutorials, there are plenty of them.Eagle has a nice library of electronic components so you just grab and drop elements and make connections.
To learn interface and some basics of using eagle i decided to make few very simple circuits based on 555 timer that were presented in one book that i bought to learn electronics. I builded all of them on a bread board and they worked fine. I’ll try to port them to eagle. Here we go…
Schematic #1 – blinking LED using 555 timer. Simple as it is, 555 working as a astable multivibrator, frequency and duty cycle of output signal is set by R1, R2 and C1. Output signal goes to LED. Its similar to servo driver described here:
Schematic #2 – Alarm using two 555 timers. Same here, 555 timers working as a astable mulvibrator. Timers are working with different frequecies, one on the left generates lower frequency. Using R1 and R3 pots you can change tone and frequency of sound comming from the speaker, really cool and strange sounds like in some old science fiction movies.
Schematic #3 – Alarm using photoresistor and 555 timer. Another simple circuit, 555 generates sound when photoresistor detects light. The light changes the resistance of photoresistor, then then Q1 starts to operate and turns on 555 timer which generates signal to speaker. Sensivity of an alarm is set by R1 pot.
Schematic #4 – Little amplifier. Input signal, for example microphone goes to pin 3 of IC. Its really simple circuit using just 6 elements including speaker and battery. You can use it to amplify signals comming from microphone or tone generators like in schematic#2.