Electrical – 555 timer digital clock

There are so many possible ways to accomplish this task.

You can build from discrete logic chips. Because you want a down-counter, this generally requires two chips per digit for the counting / display section. In addition, you will need several other chips to divide your timebase oscillator down to the count frequency that you want as well as the start - stop circuit.

It can be done - it's not hard. It's not even all that tedious.

Do note that using discrete logic chips means that you would most likely want to use LED 7-segment displays. You could drive bare LCD glass but that requires lots of logic gates to get the AC drive to the display segments.

You can also to this task using a small microcontroller. This type of project would normally require only the microcontroller (one chip) plus whatever timebase oscillator you want to use.

Using a small microcontroller allows you to choose whether you want to use LED displays or a small character-based LCD display.

The downside of using a microcontroller is that you have to write the firmware that does the application that you want. Also note that this is an upside - you can easily add features that would not be easy (or even possible) with a discrete-logic design.

Decide which way you want to go and modify your question accordingly. We'll help you get to the end of the project.

discharged is about 0V, 0V from 6V (where the capacitopr is connected) is 6V, so the input sees a high voltage.

the negative terminal of the capacitpo is not connected ot 0V so it will not always be 0V, but the resistor will try weakly to make the voltage there become 0v.

So, when the 6V is turned on the top end of the capacitor jumps up to 6V and the bottom end follows it upwards, the 555 sees this a s a "high" and turns off the output.

The resistor pulls down on the bottom end of the capacitor charging it, as it charges the difference between the top end and bottom end increases, when it gets to 4V of charge the bottom end voltage is at 2V above 0V and the 555 sees it as low and turns on the output.