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Why do you need two power supply grounds?
So the ground on the battery and the ground on the Arduino could be quite different if referenced to one another or to a different point. The only way you can be sure you have a system with 5V and 9V supplies is if they have a common reference point.
Can I connect two power supply GND togheter?
I use a 5V power supply for it (by now a 2A phone charger), and it will controll a “power board” with some MOSFET, etc running at 12-24V. The power board is connected to an external 12-24V switching power supply. Can/should I connect the two power supply GND togheter? You have to connect them, otherwise your circuit will most probably not work.
Is it safe to connect two power supplies?
All sorts of unwantted reactions could take place. For common electronics applications it’s generally safe to use a common ground for things like multiple power supplies in the range of -12 to +12 volts or so, the less current you’re dealing with the better.
What’s the best way to connect two grounds?
The best method is to connect the two grounds at exactly one point. This is called the star point. Make sure the ground connection from your power board has low resistance (thick wire) to keep the voltage drop over it small.
Do you run a ground to a high power circuit?
If you are using a mixing high power devices and logic, it is a good idea to run the respective grounds separate from each other to the respective devices, i.e. one ground to the high power circuits and another to the logic devices. Both would be tied together at the actual power supply.
Can a star ground be used for two different voltages?
If you build your voltage regulator on breadboard or PCB you will probably select a star ground topology If you are using a mixing high power devices and logic, it is a good idea to run the respective grounds separate from each other to the respective devices, i.e. one ground to the high power circuits and another to the logic devices.
Do you separate ground connections for two different voltages?
I have always been told that if we are using a circuit with two different voltages (say 5V and 12V) we should as much as possible separate the grounds. Is it ok now to use just ONE GROUND connection for both 5V and 12V circuits???