Electronic – Capacitor voltage influence

capacitordesignvoltage

I have edited the question to make it easier to explain what I am asking for.To make it clear, I have deleted the part with the 555 timer.
I have a question regarding the following:

schematic

simulate this circuit – Schematic created using CircuitLab

I know that once the battery is connected, the capacitor is going to have a varying voltage across it until it will be fully charged, reaching 7 volts. During this time, what will happen to the other two branches (the ones with the two resistors) ? According to the law of parallel connections, the voltage measured across any component will be the same, equal with the one of the battery. As the cap. charges, will the other branches have a varying voltage across them too, or will they have a potential difference of 7 volts from the beginning across them, as the capacitor?

Best Answer

Have a look at the image on this page. It's one of the representations which are clearer on how the IC works. I'll reproduce the image here:

enter image description here

You can clearly see that the voltage divider is independent for any pin of the circuit (well, except Vcc and Gnd). So the 1/3 and 2/3 voltages are just derived from there, but the actual comparison is done by two comparators, which take the pin 2 and 6 voltages to set and reset the F/F (flip.flop)

EDIT: Just found this diagram from the Texas Instruments LM555 data sheet, which is also quite neat:

enter image description here

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