[sdiy] Clock-controlled filters?

[Ullrich Peter]

Hi!

I designed a tracking filter for a measurement circuit for balancing high speed spindels of RC model aeroplane turbines.

The clock to which the filter frequency had to be adjusted/regulated was the spindle rotation frequency (generated with a reflectocopler that made nice pulses due to black markings on the silver spindle). The used maxim filter chip needed 100 times the frequency for proper work so I added a 4046 PLL chip.
The result was a  bandpass filter that moved with the center frequency.

I think this design could be adapted for audio usage by recalculation.
I used a MAX267 switched capacitor filter chip for that.
http://www.maximintegrated.com/datasheet/index.mvp/id/1186

Ciao
Peter

http://www.ullrich.at.tt


-----Ursprüngliche Nachricht-----
Von: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-bounces at dropmix.xs4all.nl] Im Auftrag von cheater cheater
Gesendet: Freitag, 19. Oktober 2012 11:03
An: synth-diy
Betreff: [sdiy] Clock-controlled filters?

Hi guys,
are there filter designs, not necessarily resonant, which tune to pulse train input?
Chips are good too - although being able to make it discrete if/when the part becomes obsolete would be a huge plus.

Cheers,
D.
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