[sdiy] RC filter questions + SPICE RC filter simulation questions

[cheater cheater]

AH!

On Fri, Apr 16, 2010 at 23:54, Neil Johnson <neil.johnson97 at ntlworld.com> wrote:
> Hi,
>
> cheater cheater wrote:
>>>
>>> http://www.logbook.freeserve.co.uk/seekrets/index.html
>>>
>>> look at the picture of the back cover and have a go at simulating that
>>> circuit.
>>>
>>> That should entertain you :)
>>
>> I see a low-pass filter. There's indeed a bump on one side of the top
>> capacitor and not on the other. What more can you tell me about this?
>
> As the contents PDF neatly puts it:
>
> "The unusual RC circuit on the rear cover gives a maximum voltage gain of
> just over 15%. Ordinary RC circuits give less than unity voltage gain. "
>
> Its one of those little trick circuits analogue designers use to entertain
> or surprise those not so familiar with analogue circuit design.  Ordinarily
> an RC circuit alone would have less than unity gain, albeit with some
> frequency-dependent response.  This circuit exhibits a "resonant peak" with
> voltage gain rather than attenuation.
>
> Neil
> --
> http://www.njohnson.co.uk
>
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