Teensy 3.0 with External Power Issues


New member
Hey, I'm just testing this out for a bigger project. But whenever I switch from USB Power to 5V external power, all the LEDs start to flicker and go crazy. What am I doing wrong? I'm going from the 5v external into the teensy then to the LEDs. Any help? On a tight deadline. Thank you
Have a 'scope to look at noise on 5V power? You may have to use an inductor and capacitor (low pass filter) to feed Teensy a better power. But you'd think that the 3.3V regulator in the Teensy would deal with this.
Grounds: make sure the Teensy's ground goes directly to the power supply's GND terminal so that the LEDs' current spikes on its GND doesn't affect the Teensy.

This is what I mean
Power Supply GND -> wire -> junction where GND goes to Teensy and GND goes to LEDs. This "wire" will get current spikes and the wire is in common with Teensy's GND. Not recommended.
Don't have a scope around to look at that. Don't usually do these kind of projects. But below is a picture of my teensy and where power is being run.

red = 5V
white/blue = ground
green = data