Here are PCBs and photos of all currently considered solutions for O-ESD excitation.

PCB for the circuit based on resonant energy transfer is in the folder 1-Resonant. 

PCBs for two excitations based on audio amplifiers are in the folder 2-Audio.

Photo of ESD that uses flyback configuration as excitation, with trafo, cascade, microcontroller,  
and external power supply, that is currently being tested is in the folder 3-Flyback. 

Photo of ESD that uses push-pull configuration for excitation, with trafo, cascade, microcontroller  
and external power supply, that is currently being tested is in the folder 4-Push-pull.

PCB for single cascade that is currently used and tested is in the folder Cascade_single. 

PCB for double cascade that is currently used and tested is in the folder Cascade_double. 

Photos of multiple commercial and designed/prototyped trafos are in the folder Trafos.