Connecting Motor makes circuit go loopy

[rpter]

It's been a long time since i've played around with electronics, anyway i figured i start again and decided to start with PICS.
So my first PIC circuit (16f84A) is up and running flashing an LED.
Now i've decided to connect a transistor to the pin instead of the led.
I've used a TIP120, but as soon as i connected my dc motor the circuit goes loopy, i have another led flashing and its a though the motor is screwing up the timing.

when i replace the motor with a resisitor and led (via the transistor) it works again, so everything with the transistor is fine.

i've tried everything i can think of (so far anyway...), but now i'm just puzzled, i know i must be doing something really obvious wrong, but i just cant figure it....
i've tried using a different power source for my motor(connecting the 2 diff power source GND's together), but this just did the same.
i'm using a variable regulated bench power supply....

Any body have any suggestions?

Thanks

Roland

 

[MP1]

rpter,
This should actually have been posted in the microcontroller area for best responses. Why don't you post your circuit and question there? Just so you know, a PIC cannot source much current.

MP