Using “Trial and Error” to set a long time period would be very tedious. A better solution is to use the Setup tables provided; and calculate the time required for Pin 7 to go high. The Setup tables on both schematics are interchangeable. They’re just two different ways of expressing the same equation.
For example, if you want a period of 9 Hours, the Range table shows that you can use the output at Pin 2. You need Pin 2 to go high after 9 x 60 x 60 = 32 400 seconds.
The Setup table tells you to divide this by 512; giving about 63 seconds. Adjust R4 so that the RED LED lights 63 seconds after power is applied. This will give an output at Pin 2 after about 9 Hours.
This Timer Circuit Diagram was designed for a 12-volt supply. However, provided a suitable relay is used, the circuit will work at anything from 5 to 15-volts. Applying power starts the timer. It can be reset at any time by a brief interruption of the power supply. The reset button is optional; but it should NOT be used during setup. The time it takes for the RED LED to light MUST be measured from the moment power is applied. Although R1, R2 and the two LEDs help with the setup, they are not necessary to the operation of the timer.