5/15/11 - 555 Timers

I started my new project today. I am working on a fully discrete hardware led clock. These are my goals for this project:

1. Create a functioning led clock with reset switch
2. Use all discrete components
3. Etch a custom PCB for the final clock.
4. Learn about simple digital circuits.

My projected sub-projects for this project are:

1. Develop a clock signal.
2. Design logic circuit.
3. Design led and digital circuit.
4. Build test bench.
5. Design and etch PCB.
6. Build final product and test.

Step 1:

I started by investigating 555 timers. In the picture below I built a prototype 555 timer circuit to make the led blink.

I used two 2200 Ohm resistors and a 47 uF capacitor to set the frequency and a 10 Ohm resistor on the led.

I have read that creating a steady accurate signal using 555 timers is rather difficult, however, and have decided to investigate crystal timers as the source for the clock circuitry.