Electronics at work.
At the beginning something simple to warm up your solder iron, totally without any software - blinking electronic. You may also do it using TTLs, a timer or an Controller. Instead of BC307 BC308, BC309 or BC556-BC559 should work as well. For each side a pair of flashing lights are connected to Out1 and another pair on the other side to Out2. The common pole is PD1. "Revision c" shows different layouts for bulb or LED operation.
The first layout has been large, because i only had a 50V type C1. Normally an eighth of an Euro card should be enough.
Version 1.0, Revision C BUBLINKc_Best
switch control for 12 switches (half euro card)
Version 3, Revision D Weiche3d<---- top
Interface V24 ---> TTLInterface: V24 ---> TTL