Users who may have done considerable head scratching re seemingly inexplicable equipment failures, noisy audio and ADC results eg. noisy Pot readings in a Midi controller or observed sparks when plugging in a USB cable or whatever may find this interesting:-

http://sound-au.com/articles/external-psu.htm#kil

The author's primary focus is on A/V gear however the same circumstances apply when we have a computer at times connected to a Teensy project and it's relevant peripherals.

How the Teensy project is powered and What (if any) other external equipment does said Teensy project connect to are important considerations.

If I posted in the wrong place, 'scuse me, am a newbie to this awesome Forum and a recent Teensy convert.

Excellent stuff. Cheers