This is my first use of a transistor, and I think I have the circuit correct as it works fine when the Photon is on. However, when the Photon goes into Sleep_Mode_Deep, it kicks back on (at a slower speed). He’s a simple diagram of what I’m doing:
@okeefe, in deep sleep ALL Photon pins will go into high impedance mode (floating). To fix this, you need a bias resistor on the base of the transistor to keep it OFF when the GPIO floats. In your case, a 4.7K to 10K ohm resistor to GND should keep the base from floating. Think of it as a “pull-down” resistor.