I am working on a project in which I will have two different power sources, which I will have to dynamically switch between to supply power to devices. These two power sources will likely be similar in voltage, but may vary slightly.

I figured that the best way to approach this would be by putting the voltage sources in parallel, but if there is a difference in voltage, current will flow between the sources, which is not what I want. I then had the idea to place a diode in series with each source before they are connected, to ensure current does not flow between them (Both sources are DC). I don't see why this wouldn't work, but what would the voltage be of the sources in parallel?


The higher voltage of the two sources minus the diode voltage drop.

  • \$\begingroup\$ Okay, that makes sense. Will current be drawn from the source with the lower voltage? Or will it only be drawn when the higher source's voltage drops (due to load) to the same as the lower voltage source? \$\endgroup\$ – John Leuenhagen Sep 1 '18 at 19:00
  • 1
    \$\begingroup\$ @JohnLeuenhagen No, current from the lower voltage source will be zero. If sources are equal, the current drawn from sources will be equal, assuming everything is ideal. \$\endgroup\$ – Ma Sa Sep 1 '18 at 19:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.