I am about 23 years out of my college days of building circuits and some concepts have escaped me... The most important being signal loss.
What I would like to do is build a fairly simple device.
Audio in -> 3 way split. 1 for loop out, 1 for sending to a TI3917 for a meter, and the third into my Arduino for some extra features.
What I am not sure about is signal loss... I know how things work in the macro world of video and audio and you will get signal loss without "termination" and in the wires themselves but its only significant over long distances and I can compensate for that. I've completely forgotten how this might effect things when you get into such short paths on a board.
Can someone point me to some information about distributing signals... and ensuring that each new signal is the same as the original?
goblynn93:
I am about 23 years out of my college days of building circuits and some concepts have escaped me... The most important being signal loss.
What I would like to do is build a fairly simple device.
Audio in -> 3 way split. 1 for loop out, 1 for sending to a TI3917 for a meter, and the third into my Arduino for some extra features.
What I am not sure about is signal loss... I know how things work in the macro world of video and audio and you will get signal loss without "termination" and in the wires themselves but its only significant over long distances and I can compensate for that. I've completely forgotten how this might effect things when you get into such short paths on a board.
Can someone point me to some information about distributing signals... and ensuring that each new signal is the same as the original?
Thanks much!
Well first you have to come to terms of that an arduino analog input pin cannot directly deal with AC voltages and audio is a form of AC voltage. Voltages of signals wired to analog input pins must be restrained within a 0-+5vdc range. So at best you are going to need external circuitry to properly interface audio to an arduino. Second there is little useful that an arduino can do with a audio signal based on it's limited resources and power. Perhaps if you explain what the 'extra features' might be we could make suggestions?
Signal losses is not normally a problem with arduino inputs and output circuits.
I am not worried about the audio into the Arduino, I am more worried about degrading the audio quality before it hits the Arduino at all.
My plan is to use the TI chip for a basic VU meter just to know audio is there and then build a VU meter with the Arduino as the controller using raw LED instead of the 10 LED bar I plan to use with the TI3917.
My use of the word "features" was probably improper... "Styles" would probably be more appropriate.
I want to be able to take the headphone level audio from a headphone jack and:
I want to split the audio 3 ways:
1: loop out so I can plug in headphones and listen to what's coming into the audio port.
2: TI3917 powered VU meter for visual confirmation of the audio.
3: feed the audio into the Arduino to be able to alter the behavior of the meter by changing the code.
Major bonus: the audio sent to all 3 destinations is identical, no signal degradation.
This project is an experiment to see how much I can do. I used to build FM/AM radios from scratch/schematics but I have very little experience with micro-controllers and controlling "smarter" circuits with code.
Eventually I would like to expand into something like this (as I get better at all this!!):
The normal way you'd do this is buffer the audio signal with an opamp which then
drives the 3 outputs via any resistive dividers needed. But that requires a suitable
supply (depends on the line-level of the audio signal what you can get away with,
studio systems use 4V rms or similar, most domestic audio about 1V rms) The former
needs a good split-rail +/-15V setup really, the latter will work from 5V single
supply using rail-to-rail amps.
If you can get away with a passive network its a lot simpler. Audio signals are
often voltage driven but assume high-impedance loads (10k--47k or so). If everything
has high impedance inputs just parallel them?
