Kieran,

An inductor presents a high impedance to AC (jwL ohms).  So if there is
noise in the circuit, it won't get back into the power supply.  This
does a couple of things: it keeps other parts of the circuit from
getting this section's noise and it helps reduce EMI over system.

--
Robert Wuest, PE
Sirius Engineering Company

Kieran Miller wrote:
>
> Hi Picsters,
>
> I know a little about decoupling and the theory behind it, but something in
> the attached schematic confuses me. Why is the inductor L2 needed? I know
> why the two caps are there - but the reasoning behind the inductor is lost
> on me.
>
> Anyone care to enlighten me?
>
> The full schematic can be found at
> http://133.205.9.101/~elm/reports/mpc/mpc_c1.gif , and the decoupling is on
> both the digital and analogue power inputs to U4, the DAC.
>
> Many thanks,
>
> Kieran
>
> --
>   Visit The Northern Ireland Macintosh User Group
>              http://welcome.to/nimug
> Send SMS messages via email: kmiller@sms.genie.co.uk
>             Fax: +44-(0)870-131-9044
>
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