Hello,
first of all I’d like to apologize if I’m in the wrong thread.
I’m using multiple cascaded shift registers and several Hall sensors to build a MIDI piano.
The datasheets of both the shift registers and the Hall sensors recommend using decoupling capacitors.

My question is:
Is it sufficient to use a single 100nF capacitor for all of them, since the capacitor is connected between VCC and ground (see screenshot 1)?


Or should I use a separate capacitor in front of each Hall sensor and each shift register (see screenshot 2)?



I assume that one capacitor should be enough, because otherwise you would have a parallel connection of capacitors, which would lead to a high total capacitance.
With 42 Hall sensors and 6 shift registers, that would result in 4800nF = 4.8µF.
Am I right?
I would really appreciate your help.
Thank you in advance!

 

Rule of thumb is, each IC should have it's own decoupling cap, as close as possible to the IC.. there are some tips about placement and orientation for decoupling caps on IC's you should find that stuff easily on the internet.

For these simple IC's you could probably use few, bigger decoupling caps, so you can group the IC's somehow to share the same capacitor.

 

Thank you.
But what about the fact that all capacitors are in a parallel connection, since each capacitor is connected between VCC and ground, resulting in a large total capacitance?

 

Large is relative term... I would not concider 5uF large..

 

Ok, thank you