Hey there everyone,
Let's say I have a power supply set up to output 5V. It needs to power a device to a negative voltage, so the positive rail is attached to ground with the negative rail hooked up to the device. An arduino is connected to the wall and it's ground is connected to the ground of the circuit. What happens? In other words, in practice, does adding a negative voltage power supply move the ground plane?
Thanks
Most all power supplies will have isolated outputs ... an isolated supply will not move the ground plane.
You could do a quick test by using a series 1K resistor to connect the auxillary supply's 5V to the ground of the circuit. Now measure the auxillary supply's -ve terminal and it should read near -5V. If so, you can safely make a direct connection.
Either if the GND is connected to the computer ground, or just floating, adding the -5V (using a normal 5V power supply) does not change it.
Awesome!
Thanks guys!