piclist 1999\10\28\102144a >
Thread: HT9200A problem (DTMF)
picon face BY : Lea email (remove spam text)

At 10:51 AM 10/28/99 +0300, you wrote:
>Hi Leandro,
>You cannot filter the DC jump out of the signal, because the jump has wide
>spectrum including DTMF frequencies band. The only approach I would suggest
>is to use some external circuit that would hush the encoder output at the
>beginning and end of transmission. Though, it's complex. Better switch to
>another encoder, e.g. Philips PCD3312C.

Hi Nikolai, I'm very sad to heard this because I already buy 20 parts!!!
mmm I was thinking about use a 4066 switch so I think that it will not increase
the cost too much but I will need an extra pin out of the pic to control that
gate and this is a problem :).
I will inquire about the Phillips Chip here, see if I can find it in argentina

>I am not familiar with that chip, but how about providing a DC bias to the
>level it jumps to? then use a coupling cap to only get the tone.
>    cya,    Andrew...

Hi Andrew , I already did that but does not work, may be because the change
of state generate harmonics in high frecuencies, I don't know why but still
not work :(.
  Leandro J. Laporta (LU2AOQ)
  mail: .....lu2aoqspamspamyahoo.com
  wrk: Arg. Assoc. for Space Technology.
  ham: TCP/IP high speed group HSG


See also: www.piclist.com/techref/pots/dtmf.htm?key=dtmf
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Subject (change) HT9200A problem (DTMF)

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