3. VA Meter
For display we use cheap voltage and current meter. The meter used here has two lines for powering the meter (red and black) and three lines used for measuring in a common cathode connection (red, blue and black). We can connect the measuring lines as shown in the above image. The meter needs a power supply (from 4.5V to 30V DC), we can use a 15V from a standard regulator 7815.
This is the assembly of the external parts of the circuit to the PCB. I made the case from textolite sheets that have beams on their sides through that connect with other sheets. Beams are drilled and glued with epoxy resin. This makes the bond strong enough to carry the construction.
The enclosure is tightly packed but holes for air circulation around the transistors must exist. Finally I painted the case white with a spray color.