Help with breadboards acting flaky

I’m a programmer and a hobbyist arduino user. I can solder well, even do SMD stuff. I’ve made Velleman kits that are hundreds of components, and they actually work fine.

So why is it that breadboards are just unusable for me? :grimacing:
i’ve got a simple circuit build with an arduino pro micro on a breadboard. You push the button, the onboard LED turns on while you’ve got the button pressed.

Why can I wave my hand over my breadboard and the light blinks like i’m pressing the button. Why does the light stay on (after i’ve let go of the button) and slowly get dimmer then turn off.

I just don’t know why my circuits do completely crazy things just bc they’re on a breadboard.
Any ideas or insight anyone?


Pictures of the breadboard? Sounds like a loose connection or a grounding issue.


Cheap breadboards are notorious for flaky clamping of your wires and component leads.

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You’re missing a pullup or pulldown resistor on the connection between the Arduino and your button. Without it the pin acts as an antenna.

Optionally, you can use the internal pullup resistor.


The above replies are excellent and feasible but I tend to vote with @Brian. An analog input without a pull up or down resistor can swing wildly.

Are you using an analog or digital input pin? Please post your program and circuit diagram or description. Is it possible that the program uses one pin and you have connected to a different one? Plug and unplug the jumpers a few times to improrve connections.

I’ve purchased 30 or more cheap breadboards and hundreds of jumpers for my Arduino classes and personal use. Most work very well but there have been a few failures.

Troubleshooting is a great quarantine activity.


Love love LOVE this sentence :slight_smile:

I’ve been working to catch up on getting my arcade repairs orders for others done - 10 boards so far this month. It’s like solving puzzles. :slight_smile:


Missed floating inputs make trouble shooting interesting.
All inputs have to go somewhere always.
Something one learns early in the hobby.


Can enable internal pull-ups in the pinMode() call.

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