This cable lets you run a Game Boy without batteries. It powers the cable from any 5V USB power source via the built in Game Boy DC input socket.
- Male USB Type A to 2.5mm x 0.7mm DC Barrel Jack Cable
I found min on AliExpress by searching "USB to DC 2.5mm x 0.7mm"
- DD0403MA based 3V or 3.3V LDO module (no header pins) I found min on AliExpress by searching "3.3-6V to 3V 3.3V DC-DC Converter"
- Heatshrink tubing with adhesive lining - I used 8mm diameter, dual wall, 4:1 ratio
- 2 x 15mm long
- 1 x 40mm long
- Hot glue (if heatshrink doesn't include adhesive)
- Side cutters and wire strippers
- Soldering iron
- Hot glue gun (if heatshrink doesn't include adhesive)
- Heat source for heatshrink
- Digital multimeter
First, cut the USB to barrel jack cable in half around 7cm from the USB end and strip around 1cm of the wire jacket on the USB half and 2cm on the barrel jack half to reveal the two inner wires. Strip the inner wires' jackets a few millimeters.
Identify the positive and negative wires coming from the USB half of the cable using a multimeter. To do this, with the USB plugged in to a USB power source (power bank or USB power adapter), probe the two wires and you should see +5V when the red probe is touching the positive wire and the common probe is touching the negative wire.
Likewise, if you aren't sure of the configuration of the barrel jack (centre poitive vs centre negative), continuity probe the wires on that half of the cable to determine which is connected to the centre of the jack. Pocket/Color/Light Game Boys use centre positive barrel sockets.
- The red wire is the positive wire and a grey, the negative wire on the USB end; and
- the red wire connects to the centre contact of the barrel jack and hence the grey, the outer contact.
Before making the solder connections, pre-shrink any heathshrink being used to thicken the cable onto the cable halves.
Place the heatshrink tubing you need on the DC barrel jack half of the cable.
Tin the pads of the LDO module. I am using a 3.3V module to give a small extra amount of voltage to allow for use of an IPS screen and potentially a flash cart.
Solder the wires from the USB end of the cable to the input pins of the LDO Module - G for GND (grey) and VI for Voltage In (red).
Solder the wires from the DC barrel jack end of the cable to the output pins of the LDO Module - G for GND (grey) and VO for Voltage Out (red).
Add hot glue to reduce potential strain on the wires if not using heatshrink with adhesive included.
Shrink the main heatshrink over the newly added module.
Test the cable while the USB has a power source checking that 3V (or 3.3V) is available at the barrel jack (with positive centre!).
Enjoy using USB to power your Game Boy!
If you are willing to adjust the wire lengths to minimise the gap between then LDO module and the outer cable jacket you should be able to get a more uniform result when heatshrinking like below.