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

[Neil Johnson]

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