I have a project I want to make but not sure how to start. I will post short description about the project and I hope someone could give me some answers. Thanks in advance!
The main thing I want to do is regulate RCA input signal from car head unit (max 4v signal) and regulate it with rotary decoder. The second thing is that it should be wireless. So there is one arduino that have rotary encoder connected and is battery powered and second arduino have hub with rcas input and output and its powered via car electrical.
This is just a basic idea.. I have some more minor things in mind like regulated volume bar and car voltage reading on arduino display.
How hard would that be to make? Do you have some good guides or tutorials I should read or watch?
You need an encoder, not a decoder for the twiddly bit, an RF link of almost any type to connect the two nodes, and a ‘receiver’ with some form of stereo audio attenuator in the RCA audio cables.
Fiddle with the encoder, send the selected gain facto cross the rf link.*
Receive that data, turn it into control for digital potentiometers or an attenuator of sone sort.
You can either use the absolute value of the encoder/sender to set your gain, or feed a pack from the receiver ypto provide a relative gain adjustment so the encoder/sender stays in sync with the receiver *
(1) you can display the encoder value as an absolute value being sent to the receiver, or (2) return the receivers ‘gain value’, and display that for the knob twiddled.
Right now I'm playing with connecting RCA audio signal to arduino. I know that arduino cant read negative voltage and can be damaged and that I need DC offset to get audio input.
But not sure if this exact DC offset is right for my application.
My rca signal voltage output is max 4v and frequency range from 15hz to cca 100hz.
My question is do I still need capacitor in dc offset in my case? I don't want to affect any incoming frequencies from rca signal.
The capacitor is required to decouple DC potentials. It let only the AC part influence the "other side". Otherwise you would feed your RCA input with 2.5 VDC. And you possibly do not know the DC potential difference between your Audio equipment GND and your Arduino GND, so connecting those on DC level might already damage one or both sides.
Hmm okay. I didnt hook up anything yet because I dont want to damage arduino or something else. Well now when we solved this I'm not sure how can I this input signal that is getting attenuated via digital potentiometer send back to Rca output to amplifier. Because arudino doesn't have analog output right?
The pin marked 'RW' and coloured green is the wiper.
You would need two digital potentiometers like that for stereo
I don't think that particular digital potentiometer (X9C104) is suitable for audio as it is a linear taper. You need to have a logarithmic taper for audio.
Input signal should be stereo because each RCA have half of the voltage (2v per rca) and output signal can be mono but it should output same voltage as Input (4V) Would I still need two digital potentiometers? I could probably connect inputs together in parallel so I get full 4v signal and output could be only one rca with same voltage as input. Am I on right path?
Isn't the logarithmic taper analog potentiometer right? Because one part of this project is that signal should be regulated remotely with rotary encoder so I assume I cant use logarithmic pot in this case or am I missing something?
It sounds doable.
