The RemoteHF borad has a dedicated power supply unit supplying 12 and 5 volts. It consistes
of two boards, one supplies isolates power and the other non-isolated power.
Please note that the TIP42C and LM7805 need to be insulated from the heat sink as the tabs are at different potentials.
The Rpi is the on the five volt isolated supply and is the only large current draw? COnsequently we should favour 5 volt isolated supply rail for heat dissipation.
It is recommend you mount the parts to the heatsinks before soldering them in the PC board. It is difficult to access the screws considering the board layout.
Install a 1Meg resister between each negative output to the case (mains earth).
Also note the fiber insulator washers on the standoffs.
Installed a 12V fan on the heatsink that is powering the 5v rail for the Pi. Ideally, a lower output transformer would reduce heating. After several hours of running the Rpi the tempreature reached about 45 degrees on the case of the LM7805.