Not all switch have there own power source, some of the switches are connected with two or more power sources so it is best to have additional switches to avoid a blowout.
A flashlight typically uses a parallel circuit design. In a parallel circuit, each component has its own separate path connected to the power source. This allows each component, such as the bulb and the switch in a flashlight, to operate independently.
Each research station provides its own power source from its own power plant. Field camps use portable means for power, and primarily these are gas powered.
Most subwoofers have their own power source. There are subwoofers called "passive" woofers that will be powered by your amplifier.
Ohm meter
The Audio Technica wireless headset microphone does need its own power source, but the power cord is very small and discreet.
You may have a short in the power window switch.
Each research station provides its own power from its own power plant.
When using network switches, each port on the switch is its own collision domain.
Usually RFID tags would get the power from the reader.
Research stations generate their own power, usually from gas-generated motors.
On a switch each port is its own collision domain, therefore collisions do not happen.
To properly wire a bathroom fan and light together, you will need to connect the fan and light to a double switch. The fan and light should each have their own wire connections to the switch, with the power source coming from the main electrical panel. It is important to follow the manufacturer's instructions and local building codes when wiring the fan and light to ensure safety and proper functionality.