Like many others, I have been working on a handheld gaming system using a Raspberry Pi Zero. One of the downsides of doing this, however, is that it has no sound built in, other than through the HDMI port. I have looked into getting the GPIO pins to output sound, but it is quite complicated and can be expensive. I just noticed the pHAT DAC and it seems perfect. It is a hat that can go straight onto the RPi and has R and L output and even a 3.5mm headphone jack. However, I am trying to keep my project slim, and male-to-female cables are bulky. Does anyone know if there are spots on the PCB of the hat that I can solder my own 3.5mm jack onto? This way I can keep it slightly thinner and have the headphone jack wherever I want on my handheld.
asked Oct 28, 2016 at 0:23
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2Welcome to the Raspberry Pi flavoured corner of the Stack Exchange Network. It isn't obvious to me that the output from that device is powerful enough to directly drive, say, a pair of headphones - it may only be a "line-level" output that would need to be amplified before it could be fed to a pair of speakers/headphones.– SlySvenCommented Oct 28, 2016 at 1:41
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Hmm, according to this post, someone was using the jack for headphones, although they never specifically said whether or not they plugged it into any external devices. forums.pimoroni.com/t/phat-dac-speaker-to-headphone-switching/…– thatoneguy245Commented Oct 29, 2016 at 20:36
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1 Answer
Looking at the image of the device here, hopefully reproduced below:
It ought to be possible to unsolder the five surface mount connections that attach the 3.5 stereo socket to the PWB and connect some skinny wires to the pads which (after bonding the wires with some hot-melt glue to reduce the chance of the wires being yanked off the PWB and ripping the pads on the PWB that they are connected to) can be run to your own nearby externally mounted socket). It is not clear whether two of those five - being contacts in the socket that would carry the audio left and right signals back to internal circuitry if a plug is NOT inserted - actually serve any purpose in this application... (if the adjacent RCA "Phono" sockets were installed it might be that they would carry the audio output if a connection was not made to the jack socket!)
This would most likely invalidate any guarantee that the product supplier would otherwise give you.
It might be worth contacting the supplier and asking whether they could source a unit without the 3.5mm socket fitted - if you explain very nicely that you really need to keep the overall height of your assembly down in an already designed enclosure, but I would not be overly optimistic that they could do this unless it is something that they build themselves and could take the time to do one without the socket. On the other hand if they had a "reject" one with a broken socket they might be willing to do a deal!
You will also likely have to figure out the wiring but a test 3.5 plug, the original socket removed from the board and a multi-meter set to it's continuity "buzzer" mode (and an extra hand or two to hold both meter leads AND the socket 8-) ) will probably allow someone to work out how to connect an external socket to those wires.
Addition:
If you do manage to get a board without the socket you may need extra skill to work out the wiring - however with a bit of searching I was able to find what looks like the socket (or a clone of it) which suggests which pins might be which - try the .pdf file for the 35RASMT4BHNTRX part on this "Switchcraft" website page.
In summary, from the top looking down and from the edge of the PWB onto the socket: the pin furthest from the PWB edge (at the back) is 5, the two close together on the left are 2 & 4 with 4 nearest the edge and on the right the one further away on the right side is 3 and finally 1 is the one nearer the PWB edge. Then the pins are:
- Sleeve - Ground
- Ring - Right Audio
- Tip - Left Audio
- Connected to 2 when no plug inserted
- Connected to 3 when no plug inserted
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Thank you! I am quite busy at the moment so I can't currently further advance this project, but once I get the chance I will definitely take your advice! If at all possible, preferably having the supplier sell me one without the jack, so that way I won't have to worry about taking it off myself and possibly damaging the unit :P and I may have to amp up the output because as you said, it is possible that it can't directly drive headphones Commented Oct 29, 2016 at 20:42