A basic question

[albert]

Hi everyone,

Why is there usually a capacitor connected between two connectors of
some instruments such as a voltage supply, or between the supply line
of a breadboard and its groud plate?

Thanks,

Albert

 

[Bob Morein]

Hi everyone,

Why is there usually a capacitor connected between two connectors of
some instruments such as a voltage supply, or between the supply line
of a breadboard and its groud plate?

Thanks,

Albert

To provide a short-circuit path for noise which is injected into the power
buss by the circuitry on the board.
The power supply, if not mounted on the same board, cannot efficiently do
this.
The bypass capacitors compensate for the fact that the power wiring has
nonnegligible resistance and inductance.