Hope you are doing well.
I have been working with the DTMF decoder MT8870 for few months but i could not get success. I have used few circuits mentioned in the datasheet. But i am facing problem *, 0, # , 7, 8 ,9 buttons are working but sometime works the 1, 2, 3, 4, 5, 6.
Why is that???
I have connected to MT8870 Pin 2, 3 ....> 100 Kohm
But one thing i need to ask i have took dtmf toon from the mobile phone T68 speaker and connected to the MT8870 using a 5Kohm Variable resistance to control gain.
What is the working cirucit for the mobile phone.
Waiting for your supportive response.