I've recently got a Raspberry Pi and was working with a simple circuit and project, essentially I have an LED I'm powering up if a switch is open, details on the circuit and software below. Something that I have happening is the circuit appears closed pretty quick. I worked with the switch, jumpers, LED, the breadboard and everything in between in an attempt to see if there was something amiss there, everything appears fine, I noticed that even with the switch and input jumper removed altogether, the circuit would still occasionally see high input on the specific pin. I realized this was happening when I was touching the jumper, or even if I got close to the whole project; although when I had the switch and jumpers installed, I could far "enough" away and I'd still see this issue. I believe the current powering the LED is causing some interference with the input jumper for the switch and some degree of body capacitance might be playing an effect. I believe this is an example of inductive coupling? I lack any tools to measure what's going on, only a DMM which shows the appropriate voltages but is too slow to see those particular wires in the brief period of time.
Is this normal, or am I just prototyping this all wrong? The project is very simple:
I have high output on one pin leaving the rPi to a breakout board at 3.3v. This powers an LED and returns to ground. I also have 3.3v power being fed to a NO momentary switch (the Omron tactile kind), with the 3.3v returning to an input on the board. The software loops such that if the input is False or low, the LED lights up. The voltages are appropriate for the input/outputs being used. The jumpers are just these cheap breadboard jumpers, solid core 20AWG.
Attached is an picture of the project. The Yellow jumper I believe is the problematic one, this is the wire returning the value of the switch.
I'm still just beginning the practical electronics journey, so if anyone can shed some light on what I'm seeing, how I might be able to prevent it, or any other useful tips I'd appreciate it. This seems like a simple, electricity 101 problem, but I want to understand the phenomenon more than just "fixing it".