That’s really nice and a neat job on the internals. Whats the 3 mini boards you have above the Pi?
One looks like its running to the power. I just chopped my USB cable and attached it internally to the power socket - what are you doing there?
These are 3 Step down DC converters
one 5v 3A for the Pi4 another for the Display. The 3rd is 9V for the Electronium.
I use a external switched 12V/6A Adapter.
In case someone like to source this case it is a
Bopla Alu Topline ATPH-1865-250
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In case ? Ah ah… sure, someone does…
Hold on, Hold on there is an outstanding 
. . .
People are going to start blocking the sky above the battlements if this isn’t addressed soon . . . .
There’s no shortage of boiling oil you know . . .
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Mains + battery-powered Zynthian with extended case
I’ve taken the usual standard Zynthian case as start, and remodelled it in OnShape here (needs an account to view), making the following modifications:
- Added 2x18650 LiPo batteries, with built-in 220V charger. Should run about 4 hours on batteries (~at 500mA, with 2x2000mAh capacity).
- Added buttons in the case for the 4 extra custom GPIO’s built into Zynaptik (3 buttons in the front, 1 in the back)
- Added a headphone amp and socket
- Added balanced input sockets (XLR+jack)
- Added jack output sockets
- Moved MIDI activity lights to the front panel
- Added indicator lights for battery charging state and Raspberry PI activity
I can provide some pictures and descriptions of the internals if there’s interest 
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Hi,
yes of course I’m interested in more inputs, especially regarding this:
- “Added balanced input sockets (XLR+jack)”: line level, mic level, instrument level ? do you add some input buffer like preamp and so one, what is the input ADC (hifiberry adc+dac pro ?), and finally, what is your use case ?
- “Added 2x18650 LiPo batteries, with built-in 220V charger. Should run about 4 hours on batteries (~at 500mA, with 2x2000mAh capacity)”. That’s great ! But tell me more ;-))
- and of course: “what’s the hell is getting out of this”
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Ohhh! Nice and very pragmatic mount …
Don’t doubt that we are interested on them …
And of course, a 
is highly recommended too … 
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Right, here goes I’ll start with a bit about the battery. As to , my creativity tends to wander between hacking/coding and music, and currently is on the former. But sufficient to say, I’m planning to use it as guitar looping / effects panel, with a stomp box of switches talking to it over RDP-MIDI.
Target of the build has indeed been to be as pragmatic (actually, as cheap 
) as possible.
The battery
What you see here is the following:
- 2x 18650 cells with ~2000mAh capacity. I soldered wires to them (in much-heat-short-time style), but you’re probably safer off using a spot welder or something with solder tabs
- 2x HLK-PM01 embedded isolated power supply modules (220V -> 5VDC, 500mA)
- 2x TP4056-style lithium charger/protection module, modified to charge at 500mA instead of 1A, and replacing the status LEDs with a 2.54mm connector (the LED pads are conveniently ~2.54mm apart). Take care when plugging / unplugging, those pads rip right off (ahum…).
- A 3A polyfuse from “-” of one protection module to “+” of the other, to put them in series, and get a low-side battery fuse.
- 16AWG wiring on the low side, to keep voltage drops to a minimum (raspberry pi can be picky)
- High-current connector on the low side, again to limit voltage drops.
- On the 220V side, I added a small fuse, and a MOV (since nobody really knows the rating of those HLK-PM01 modules).
- 3D printed contraption that holds stuff together, which is pushed into a holder in the bigger case.
The +7.2V output goes through a buck converter into the raspberry pi, which I’ll show in the next post.
Please everyone: Do NOT solder to batteries (or heat them in any other way) unless you really, really, really know what you are doing and even then, use full protective equipment. Batteries are very likely to explode when heated and contain materials extremely caustic to human tissue, i.e. you will get covered in hot materials that will continue to chemically burn you. This is a very dangerous process that you should avoid at all costs!!! Use spring loaded battery holders or crimp terminals or other method of connecting to the battery wherever possible.
(I am not trying to undermine @jypma who I hope knows all this and takes appropriate precautions. I just want to make sure a budding amateur doesn’t end up in hospital!!!)
I look forward to the next instalment. (I have a 5V UPS type thing but my charging supply is too noisy so I haven’t yet checked its suitability.)
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+1 to everything @riban says. Be careful and respect batteries for the little bombs that they are.
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Main raspberry pi connections
This is mostly a standard V3 Zynthian, with a few tweaks:
- Raspberry Pi 4. Works fine, no image modifications needed.
- I’ve soldered 16AWG wires directly to the TP points near the USB connector, in order to inject power. After checking alternatives on the RaspPi forums, this seems to be the recommended way (injecting over the GPIO header would bypass an internal polyfuse, AND have more voltage drop. Plus, the zynthian cable is already using it
- Small single-core wires soldered on top of the Raspberry Pi’s activity LED (so I can route it to the main panel). I left the original LED in place, since both are green and have similar turn-on voltages.
- Standard EBay buck converter converts the 7.2V from the battery to just over 5V (output voltage adjusted under load, while measuring at the raspberry pi input side). I added the biggest cap I could fit, and a ferrite ring, to help with ripple noise. Ripple noise is inaudible on the main outputs (headphone amp not so much, more on that later).
- HifiBerry DAC+ ADC Pro sitting on top of the Raspberry Pi
- Balanced input is connected to XLR+Jack plugs. This lead to an interesting noise issue: when mounted in the case, I’d get noise on the input sound. But only when a MIDI IN was connected. This is strange, since MIDI IN is electrically isolated. Turns out the MIDI LED wires were running close to the input jack’s wires, and the LED current was enough to induce noise there. Ouch. Gently routing things differently got rid of that
- Standard Zynaptik module connected through the usual Zynthian ribbon cable. The loose end goes into the screen (which will be in the next post
) - The little extra red power connector in the image goes to the headphone amp I’m currently using. It’s happier with 7.2V.
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Front panel
(well, actually the back-side of the front panel)
- Standard ZynScreen module, and the four encoder PCBs with mini-JST connectors
- Headphone amp is a cheap module I got off EBay. I can’t find which one it is anymore, and it’s currently fairly noisy (switching noise, even though it’s fed off battery directly); I’m still investigating and will update the post when I have a proper solution.
- LED array has connectors that go into the charger PCBs, and the RaspPi activity LED. Sockets here are what the MIDI in, out, through connectors’ LED pins go into.
- The headphone amp’s sound input shares a connector with the extra Jack outputs, which together plug into the HifiBerry’s output header.
- The 3 front-panel buttons plug into the ZynScreen’s extra 5-pin GPIO connector. The last button position is a socket, where a button on the back panel plugs into. At the moment, the back panel button is configured for “Power off”, and one of the front-panel buttons for “Alsa mixer”.
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Thank you for all the details
Hey .!! Is it your birthday ??
Eh eh…
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Nice suitcase!! 
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Just in time for lockdown easing for foreign travel.
I wanted to know wether a Raspberry could be used as an audio engine for a digital pipe organ console. v4 makes it possible, at least with Aeolus. Great .
ce
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Any chance of a ?