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Inspiration: I haven't had much experience with integrated circuits, so I decided to take on a project that would teach me more about them. Through my research, I discovered one of the most prevalent chips, the 555 timer. The 555 timer is everywhere, and its simple design and function allows it to be used to make anything from clocks to electronic pianos. I ordered a reasonable quantity of the chip on eBay (along with a variety of resistors, capacitors, and other basic components), and looked up example projects to follow.
The Process: First, I found the data sheet here and an Instructable here. Using both as a guide, I designed and built a circuit that blinks two lights for user-variable lengths of time dependent on the value of a capacitor and a series of resistors that can be selectively bypassed.
Building the Circuit:
I started by making the connections between the 555 timer and the LEDs. I used 330 Ohm resistors after each LED to limit the current through the LEDs so that the light didn't blind me or cause the LED to burn out. All of the yellow wires connect the LEDs and the 555 timer.
I finished the resistor array that would allow me to control the blinking. Each resistor is 4.7kOhm. Next, I connected the power to the 555 timer (Vcc, RESET, GND) and the LEDs in series. PROBLEM: The red LED was on and green was off, no blinking, but I haven't added in the capacitor the the threshold yet.
I added in a 100uF capacitor to connect to the threshold (THRES) of the timer, this is the second means of control over the length of the LED blink. I hadn't connected the far rail to
the inside power rail, so I did that as well. PROBLEM UPDATE: The circuit is not working, there is no blinking happening.
I discovered the problem! In the Instructable I was using as a guide, the author uses Pin 5 for Ground (should be Pin 1) and Pin 7 for Output (should be Pin 3). I discovered this by comparing the data sheet and the functions I wanted from the circuit, then changing the circuit to what I thought it should have been.
The Circuit in Action:
What I Learned:
Through the problem solving after the circuit refused to blink, I learned how to find and use an integrated circuit chip data sheet. I now know how to use the 555 timer, a very important integrated circuit, and I should be able to apply this knowledge to other ICs. The next project I want to use a programmable chip such as the ATtiny or the ATmega on my Arduino. Finally, I realized that the 555 IC and the ATmega on the Arduino are really similar, one being far simpler and the other far more capable. This project makes me want to learn more about the creation and uses of integrated circuitry.
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