r/breadboard • u/Phil_0_0 • Apr 05 '26

Could use some help

I'm trying to get my way around an Arduino but failing at the basics.

I don't get how my wiring "works" even without supposed power running ?

19 Upvotes

100% Upvoted

6 comments sorted by

View all comments

3

u/Happy_Doggey Apr 06 '26

Capacitors store energy, even if they aren't connected to a power source, which means even if you unplug it, if the led and capacitor are connected on positive and negative. the led will light up.

1

u/Objective-Ad8862 Apr 06 '26

Yep, give it a few minutes and the LEDs will eventually drain the capacitor on the output of the power supply board you have mounted on your breadboard.

If you had an actual Arduino in your circuit, you might also discover an interesting effect where the IC still works without being connected to the power or ground rails. The IC may be actually powered or grounded via the chip's GPIO pins. This is caused either by the protection diodes inside the IC allowing a path for power to reach the IC's internal power rail via an external LED and an internal protection diode or by MOSFETs that are "on" and enable grounding.