Looking at the schematic (attached below in ZIP format) you can see the individual blocks of this projects all broken down in their basic components. What the schematic does not contain are the inputs for setting time, etc. These are customizable and are slightly different on each clock. So what we will cover is the design of the common components. The BASIC Stamp 2 is the brains of the operation here. I could have used a more powerful BASIC Stamp model and probably would have if I had used a rotary encoder on any of these, but in this case I decided to keep it simple. The BASIC Stamp drives the display using the MAX7219 driver IC. While a little pricey, I really like this chip and find that it simplifies things greatly, especially if your display contains more than 4 digits (adding seconds). The DS1302 is on the same synchronous serial bus as the MAX7219 saving two I/O lines. The DS1804 is used in this design to provide a volume control for the LM386 audio amp IC. The battery backup keeps the time when the power fails.