The 555 pulse generator is the chip that generates a pulse that can be counter. Using this pulse a timer can be built. The 555 that is being used is a CA555CE. The chip is a 8 pin chip that is powered with 5 V DC. Figure 1 shows the pin diagram and the details for setting the 555 chip to generate the pulse that is needed.
When a 555 chip is set up the size of the capacitor and resistors that you use will determine the frequency at which a pulse will be generated, as seen in Figure 1. Since the timer for this project needs to be about 1 hr and 4 counter chips (counter chips count to 15 then send a pulse of their own) will be used the capacitor that was chosen is a 0.002 micro farad. The resistor, R1, (see Figure 1) will be chosen to be 1 mega ohm. With this configuration, the 555 will produce a pulse about every 80 milliseconds. This rate was found using a Oscilloscope, by measuring between ground and pin 3 on the 555 chip. The next step is to set up a counter to count the pulses that the 555 chip is generating. Figure 2 shows how to wire up the 555 to a counter.