a fourth diode having a characteristic comparable with the characteristic of the second diode, and disposed in series between the second power supply and {HEAD ~ the second device} having a direction from the second power supply towards the second device as {TAIL ~ a forward direction}, 
a fourth diode having a characteristic comparable with the characteristic of the second diode , and disposed in series between the second power supply and { HEAD ~ the second device } having a direction from the second power supply towards the second device as { TAIL ~ a forward direction } ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH