GD77 Hotspot - Bottom Charger Part Replacement

Last crawled date: 4 years, 2 months ago

This is a replacement bottom part of the GD77 desktop charger, designed to be a DMR hotspot, with a Raspberry Pi Zero W fitted inside.
You can also replace the original charger board by a cheap TP5100 one (photo provided).
The hotspot functionnality is only available in the OpenGD77 firmware (forum)
You need to cut the small inner tabs on the upper charger part, as the walls on the bottom part are thicker than the original.
Ferrite beads (on both cables) are required to avoid EMI problems (like USB disabling).
1 Mini360 DC-DC step down converter (RPi power supply),
1 power switch,
1 Raspberry Pi Zero W,
1 SDCard to install Pi-Star,
2 MicroUSB male connectors,
1 GD77 programming cable (shortened to avoid EMI),
Adhesive copper foil band,
Wires,
8 * M2 screws (various length 3 to 6mm, reuse the original 4 ones to assemble top and bottom charger parts).
You need to put a copper foil layer under the RPi (between the bottom and the Pi-Shield parts), and also above it, between the shield parts, both connected to ground.
The FreeCAD files are provided.