Mega powered without load

Hi I have 20 solenoids connected to a mega2560, I put diodes from TIP120 collector to 12 volt power, if I disconnect the load the mega is still powered?, please advise thank you

Please post a schematic of your project

image
Hi its the same as the pic, but just with a mega and 20 solenoids

What is the source of power for the Uno?

That is no schematic.
See this tutorial to get started making schematics.

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The Mega is powered from its own power pins (barrel, Vin, USB, 5V pin, whatever you have chosen to use), not through your TIP120.

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Your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advise on) your project :wink: See About the Installation & Troubleshooting category.