HarvyH42, I put a link three post up to a couple 8870 schematics.
Can you give me a basic flow of DTMF decoder(MT8870) with 8051 microcontroller??Even with the 4 bits from the DTMF decoder, you will need to read them and have a processor deal with them, if you are doing real control apps.
Also have an interface to the decoder chip.
Is this is a school project? Maybe just light up 4 LEDs.
So you are in the 6th grade? Wish my kids here in the US were doing electronics in the 6th grade. I have scopes, just sold my 8051 emulator.
PICs and Atmel chips and programmers all over..
They like sports and video games. I will fix the video game part soon though.. Too many hours wasted.