Hi all,
I'm using DTMF audio decoder based on 8870 chip. It's a breakout board that I bought from Ebay like one of these:
https://www.ebay.com/sch/i.html?_od...er.TRS1&_nkw=8870+dtmf+audio+decoder&_sacat=0
The decoder works fine if I connect it instead of a speaker of a desktop phone's receiver. However, the decoder doesn't work if I connect it instead of (or in parallel to) an answering machine's speaker.
I don't have an oscilloscope and can't see the difference in audio signals between a phone receiver and an answering machine's speaker.
Can somebody point out why one works and another doesn't?
Thank you.
I'm using DTMF audio decoder based on 8870 chip. It's a breakout board that I bought from Ebay like one of these:
https://www.ebay.com/sch/i.html?_od...er.TRS1&_nkw=8870+dtmf+audio+decoder&_sacat=0
The decoder works fine if I connect it instead of a speaker of a desktop phone's receiver. However, the decoder doesn't work if I connect it instead of (or in parallel to) an answering machine's speaker.
I don't have an oscilloscope and can't see the difference in audio signals between a phone receiver and an answering machine's speaker.
Can somebody point out why one works and another doesn't?
Thank you.