I see these ferrite beads tied to +VCC like pull up resistors in logic circuits. What do these ferrite beads do that are also tied to +Vcc. The ferrite beads look like pull up resistors on the inputs and output of logic chips and also on the power pins of logic IC chips. The Ferrite beads smooth out the fluctuations, noise and ripple in the DC, anything else they do?

 

Ferrite beads are usually aimed at the higher (HF/RF) unwanted frequency pulses.
Max.

 

the ferrite beads are in the VCC rails for TTL and CMOS logic

 

those are uses to filter out rfi/emi. prevent rf radiation. they started using them a little after pac man came out to filter rf radiation from the games. worked for that, didnt work for the game due to ringing of the ferite choke and shunt caps falsing inputs when exposed to static discharge.

 

how does ferrite beads filter out RFI/EMI frequencies? why can't a capacitor or inductor do this

 

because it adds inductance to a wire run through it. not a lot, but enough at higher frequencies where the intrferance is worst. using both caps and beads, usual.ly in a Pi configuration, works best. shunt cap, series inductor (ferite) and shunt cap.

 

or inductor do this

A ferrite bead IS an inductor.
Max.

 

Hola Harri

He explains the basics. This could help you.

BTW, explore his list of videos. He is good.

 

I measured the ferrite beads on a huntron and the signature doesn't look like an inductor signature.

 

Would you deny these are (ferrite) inductors?

Max.

 

how does ferrite beads filter out RFI/EMI frequencies? why can't a capacitor or inductor do this

The ferrite bead is roughly the same as a single turn choke on a toroid core - just a lot smaller.