Hi, I need to use Arduino uno as an interface to drive laser operation from a programable power source. The power source as 0V (as +) and -28V (as -), and the idea is using LM7805 to convert the voltage down to 5V to trigger arduino.
The wiring design is like what shown in the diagram photo. When I tested this system with 12V battery, it seems works fine. But when I connected this system to the real external 0V/-28V power source, it messed up the circuit of external power source and blew the power source I think. The uno is still fine afterward though. This is only happened when uno is connected to laser (the device that uno will drive) when 0V/-28V power source is used, but not when the uno is tested alone with external power source. Any thought for what might be the cause??
The wiring design is like what shown in the diagram photo. When I tested this system with 12V battery, it seems works fine. But when I connected this system to the real external 0V/-28V power source, it messed up the circuit of external power source and blew the power source I think. The uno is still fine afterward though. This is only happened when uno is connected to laser (the device that uno will drive) when 0V/-28V power source is used, but not when the uno is tested alone with external power source. Any thought for what might be the cause??