[Premium-Rx] Tantalums and ceramic beads

[thoyer]

 Yes you were, but the original question was about ceramic beads.

Tom
W3TA

-----Original Message-----
From: premium-rx-bounces at mailman.qth.net
[mailto:premium-rx-bounces at mailman.qth.net] On Behalf Of Francesco Ledda via
Premium-Rx
Sent: Sunday, May 08, 2022 8:28 PM
To: frledda at att.net
Cc: Premium-Rx at mailman.qth.net
Subject: Re: [Premium-Rx] Tantalums and ceramic beads

I was talking about ferrite beads..

Sent from my iPad

> On May 8, 2022, at 18:42, Francesco Ledda via Premium-Rx
<premium-rx at mailman.qth.net> wrote:
> 
> ?The ferrite bead slows down the rising edge of any current demanded 
> by a capacitor.
> 
> Let say you have a logic device that is switching from low to high.  
> When the device switches to an high state, the device requires energy.  
> The local capacitor provides some of the energy required by the logic 
> device; consequently, the current on the power trace rapidly increase 
> to recharge the capacitor and power the load.  The current spike in 
> the trace radiates RF (EMI).
> 
> Proper design technique is to add another capacitor of the other side 
> of the ferrite bead as a local charge storage. The capacitor on the 
> other side of the ferrite bead, is  a "local" energy storage that 
> further reduces the instantaneous current demand.  The idea is to 
> reduce the risetime of the current demand. Faster the risetime, larger is
its frequency content.
> 
> Fixing EMI problems is very hard, but designing for EMI compliance is 
> much easier. I did work on EMI problems and are a real pain to resolve.
> 
> Best, Francesco K5URG
> 
> 
> 
> 
> 
> -----Original Message-----
> From: premium-rx-bounces at mailman.qth.net
> <premium-rx-bounces at mailman.qth.net> On Behalf Of Al via Premium-Rx
> Sent: Sunday, May 8, 2022 6:00 PM
> To: premium-rx at mailman.qth.net
> Subject: [Premium-Rx] Tantalums and ceramic beads
> 
> Why are the ceramic beads used when installing tantalum caps?
> 
> Sent from my iPad
> ______________________________________________________________
> Premium-Rx mailing list
> Home: http://mailman.qth.net/mailman/listinfo/premium-rx
> Help Page: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Premium-Rx at mailman.qth.net Help Contact eMail:  73 at 73.am 
> Home Page:  http://www.premium-rx.org/
> 
> ______________________________________________________________
> Premium-Rx mailing list
> Home: http://mailman.qth.net/mailman/listinfo/premium-rx
> Help Page: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Premium-Rx at mailman.qth.net Help Contact eMail:  73 at 73.am 
> Home Page:  http://www.premium-rx.org/

______________________________________________________________
Premium-Rx mailing list
Home: http://mailman.qth.net/mailman/listinfo/premium-rx
Help Page: http://mailman.qth.net/mmfaq.htm
Post: mailto:Premium-Rx at mailman.qth.net
Help Contact eMail:  73 at 73.am
Home Page:  http://www.premium-rx.org/