Adding a volume control and a headphone socket


#1

I’m looking to make a couple of additions to my Picade 8" a volume control knob and a headphone jack point.

I’m a noob so wondering if anyone has advice before I go poking around. I was looking at installing something like one of these Knobs for the manual volume control (easier for very non-technical family members to change the volume than with hotkey combos).

No sure where to start with the headphone jack, if an extension to the built in Pi board one is best with an additional switch/button programmed to change the output?

Thanks in advance!


#2

Wiring in an encoder may be one of the hardest ways to adjust the volume. Coding wise anyway, IMHO.
Not sure there is an easy way though? Its a digital signal from the PI to the Picade X board via the GPIO. The i2s bus. Thats likely why its adjusted via a menu item (via software).
And along those lines, the analog audio jack on the Pi won’t be outputting a signal. Try a set of headphones but I bet you don’t get any audio. I could be wrong but I’m thinking if the i2s is set as the audio source the analog won’t output anything. I know for a fact if HDMI is set as the audio out the analog is not sending a signal.

One option is to set the analog audio out as the default. headphones will then work. The Picade speaker won’t though. But you could wire up and analog amplifier to the headphone jack and drive stereo speakers if you wish. Put a potentiometer between the headphone jack and your analog amp and you can adjust the volume with a knob. In the picture below, a tip ring sleeve audio jack plugs into the Pi’s audio jack. That cable feeds a dual potentiometer that then goes to my amp. I don’t ever use headphones with this setup, just wanted some speakers if need be. Full build pictures are here, https://1drv.ms/f/s!AjOYwiwlwDtpgq9LUHdGiiRpn7dr2Q


#3

Hi, thanks for the detailed response. Looks like the pot is the best option for what I’m after. I might look at putting one of those on the current pi speaker set up. Then work out how to switch the headphone socket over after.

Great photos of your build - thanks!


#4

There are panel mount tip ring sleeve jacks, https://www.adafruit.com/product/3692 that you wire up yourself.
There are ones that will switch the source for you too, they basically have an interrupter switch in them. I can’t find one on the sites I buy my Pi stuff on though. The way it works is with no headphones plugged in the audio goes through the jack to your speaker amp. Plug headphones in and it stops sending the audio to the speaker amp, and sends it t the headphones instead. Like the headphone jack works on a portable radio. They will have 5 or 6 terminals instead of the normal 3.

Just to be clear though, the headphone jack and the pot don’t go on the speaker side of the amp. They go on the input side. And if the input side is digital, they aren’t going to work.

This might actually be better than the one I posted above.
https://www.adafruit.com/product/3319
Plug one end into the Pi’s audio jack and mount the other to your picade case. No soldering etc. An extension cable if you will.