Step 14: Righting the wrongs.
1 | We will be using an RKAmp1 stereo amplifier from RK Education. The amp comes in kit form, so the first thing to do is to put it together.
2 | Remove the old LDO from above the USB Hub. Compared to the 15w DC-DC converter the LDO is quite small, even with the heat-sink attached.
3 | Find a spare place for the Converter. It has brackets for bolts. I have used two counter-sunk screws, pushed through holes drilled on the underside of the lowercase. Two washers & nuts secure it to the lowercase. You can use the same power lines as the LDO.
4 | There is space on the underside of the lowercase to mount the amp. The circuit has two holes for mounting and I have used some scrap wood to raise the circuit board up so the pins don't catch in the wood.
5 | Run power to the amp, and connect in the speakers.
It has been mentioned in the comments the need to take the lower case apart to charge/change the batteries. Well taking note of this point I came up with a plan. While the main power switch is set to the PSU/OFF position I could use the DC socket with a battery charger to charge the batteries. By adding in another switch, I could divert power from powering the LapPi to charging the batteries. All I would need is a switch which moves between sending power to the batteries, and powering the LapPi.
6 | Make a mount for a DTDP switch, this switch will sit near the DC socket so check available space before committing yourself. You will need the DC input from the DC socket on the centre two pins, and outputs for connection to the batteries, and to the original switch on the lowercase panel.
7 | Measure the correct position of the switch toggle and cut out a hole on the rear of the lowercase where this will be.
8 | Attached the new switch assembly to the rear of the lower case and clean up any edges with a flat needle file.
9| Fit the batteries into their holder and then place the holder into the lowercase.
10 | Connect the lowercase panel.
11 | Power On
12 | Check that the Wifi, GPS, & Bluetooth all work.
13 | Hack the Planet!
The LapPi is shown with its big brother the FishPi POCV and its Base-Station. More information about the FishPi project can be found at fishpi.org