A Live Audio-Visual Projecting Pedal

[brian_emo]

Hello DIYstompboxes community!

For an undergraduate project I tried out making an effects box with a Raspberry-Pi that takes a guitar signal and outputs live audio-visualisations through its HDMI channel. The idea being that you could add a dynamic visual projection that reacts to the signal using DSP, though the DSP is something that is out of scope of this post. The visualisations are all created using openFrameworks.

I did all this during the first coronavirus lockdown and it turned out to be quite a large project so I'm continuing to work on this after my hand in.

As a template I used an open source/hardware kit by Electrosmash for Raspberry-Pi called Pedal-Pi found here https://www.electrosmash.com/pedal-pi

The kit was sold out so I've been using the schematic to build my own.

What I'm trying to achieve is this:

The audio signal should be left unchanged regardless of whether it is being sent to the Pi or not, to direct the input signal I'm using a 3PDT switch with a bypass. This works great for when the pedal is "off" and the signal gets bypassed and there are no problems there. The is that when the switch is "on" and the signal is being sent to the Pi I still want the signal to be sent straight to the output as well as being sent to the Pi. the signal should always be bypassed however in one of the states I also need the signal to be sent to the Pi.

I'm thinking the signal needs to be split when the pedal is 'on' however I'm unsure how to do this without losing signal strength.


Any ideas on how to split an audio signal without losing anything?

A link to the schematic can be found here, you can ignore the output stage as I won't be using it.
https://www.flickr.com/photos/electrosmash/35146470313/in/photostream/

I'm more of a programmer honestly so circuitry isn't one of my strengths but is something I enjoy learning!

Any direct tips or links to resources that could help would be greatly appreciated.

Alex

[PRR]

Welcome!

> I'm thinking the signal needs to be split when the pedal is 'on' however I'm unsure how to do this without losing signal strength.

Have you tried this? Do you have a problem?

Frequently we "split" audio the same way we split electric power to one or more electric lamps. Just parallel.

[brian_emo]

Welcome!

> I'm thinking the signal needs to be split when the pedal is 'on' however I'm unsure how to do this without losing signal strength.

Have you tried this? Do you have a problem?

Frequently we "split" audio the same way we split electric power to one or more electric lamps. Just parallel.

Thanks for your response! I have tried this yes and whilst the signal is being split the part of the signal that is being sent to output is considerably weaker. I guess unlike a parrallel circuit the split signals never rejoin as I'm sending half to the Pi.

Cheers!

[stallik]

Take a look at the AMZ splitter. It's worked for me in similar situations