As base I used a 3U rack with aluminum casing. For the backplane I used VG32 (DIN 41612 Type C 32 pins) and columns a and c are connected (effectively only 16 connections left). A specially made transformer is used as power source with the mains connector and power switch at the back of the rack. The transformer has (at 230V primary voltage) the following secondary voltages:
12V AC
12V AC
24V AC
20V-0V-20V AC
The first 12V rail is converted to 9V DC with the help of a rectifier and a LM350K voltage regulator. All voltages are secured with a 2A fuse and are connected to the backplane as follows:
Reihe | Funktion |
12ac | +9V DC |
10ac | GND |
4ac | 25V AC |
24ac | 25V AC |
16ac | 0V AC |
18ac | 20V AC |
20ac | 20V AC |
28ac | 12V AC |
32ac | 12V AC |
And here some pictures



