Hi,
Does anyone have a smart solution how to add a DTMF signal to a part if a car's 12V system. I have a device that I will control using DTMF but I can not install extra cables. It is powered from the car battery/generator and will draw up to 10A so I planned to use the same cables for both data and power supply. I would like to get 100-200 mV p-p for the DTMF signal on top of the 12-15V DC level. The DTMF signal is generated from a PIC with 5V supply.
best regards
me
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