MF5CN filter

Sean-E shudder at optusnet.com.au
Sat Jul 15 17:53:45 CEST 2000


Hi all,

No one ever mentions this chip. The Silicon Chip Waa-Waa kit, available from
just about any electronics shop, uses one. You just need to cut one trace
and install a three position switch (or extra outputs I think) to access the
unused LP and notch outputs. The design uses a resistor which can be
replaced with a pot for res (no self-osc, topical). It can also do HP as
well but I think that would require a new PCB and I'm not up to that yet.
The instructions show the use of a 2.8kHz LP (normally on the bandpass
output) to remove some 'switching noise' from the oscillator controlling the
frequency so this could be a crippling problem.
Has anyone ever used one in a module and gotten good results? It sounds
excellent so far but there's little high end in my test speakers and I can't
tell how bad the attenuation (and noise!) is. I'll do some real tests
tomorrow.

Regards,

Sean Ellis






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