switching between input powers

I need to switch between 2 input powers. 1 is 5v 1A and the other one is a solar panel that provides 6v. i want to switch between them, can i do that using 2 transistors? or do i need a circuit.


Do you need a circuit? Yes.

Can you do it? Not right now but I am sure that you can do some more research and develop the expertise to do it soon.

2 diodes will do it:
Joint the cathodes together, connect one anode to the positive of one supply and the other anode to the positive of the other supply. Connect the joined cathodes to the positive of the load. Connect the two negatives from the supply to the negative of the load.

Whichever power supply has the highest voltage will supply the load.

Use Schottky diodes as they have a lower voltage drop.

Whichever power supply has the highest voltage will supply the load.

Does that work with a solar panel, which is a current source (roughly)? If a solar panel "sees" a buck converter, for instance, its voltage will drop to roughly the output voltage of the buck converter because of the impedance the buck converter settles on. The voltage of the solar panel is determined by the load, not by the solar panel.

Just wondering if the two diode solution will work. Will go measure later.

Good question ocrdu, I don't know the answer.

What I think will happen is the solar panel will supply as much current as it can to the load and if that's not enough the 5V PSU will supply the rest.

2 diodes is certainly what I would try if I were doing this, and only try something more complex if there was a problem with just 2 diodes.

Is this thread associated with this?

Tom... :slight_smile: