piclist 2001\02\25\165818a >
Thread: DTMF Tx/Rx
face BY : David VanHorn email (remove spam text)

> > 1. Have anyone had any experience in using this DTMF transciever
> >    MC145740 ?
> > It just does not responds to any DTMF.., i guess it's the transformer side
> > that i screwed up, but basically i follow exactly what is stated in the
> > datasheet. In addition i use a Gyrator circuit to create the off hook
> > condition. The whole thing shouldn't be that difficult since i am only
> > testing on receiving. Wonder what's wrong? Even if the impedance does not
> > match, the only effect would be the strength of the signal. By putting a
> > large resistor at the transformer secondary should do the job right?

You need enough signal, in amplitude and time.
Amplitude can be too hot, but they will take a lot of loss.

You also need not too much "twist", which could be aggravated by an
impedance mismatch.

> > 2. What is the web address that David  mention for HT9200?


Dave's Engineering Page: http://www.dvanhorn.org
Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9

http://www.piclist.com hint: To leave the PICList


In reply to: <009a01c09f74$ebb4eee0$010b7ad5@dougal>
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