I want to use a transistor to power a motor but I need the motor to run when there is 0 volts to the base and shut off when the base receives voltage. How do I do this?
If it's more than a few Amperes, you'd be better off using an N-channel power MOSFET; they're much more efficient power-wise than using transistors. A P-channel power MOSFET could be used, but they are typically less efficient than their N-channel counterparts.
Once you figure out what your input signal will look like, and how much power your motor will require, we can be of more help.
I am planning on using a monostable 555 circuit as was suggested to me by mik3 so the output of the 555 will be the input to the base of the transistor. As far as the motor as I said I am not completely sure yet but lets say 5-10 amps @ 12VDC. If anything it may be less than 5 amps, but not significantly.
Would that still be a PNP BJT?
I was searching for MOSFET transistors for sale and this one would more than handle the load and the datasheet (http://www.datasheetcatalog.org/datasheets/50/118235_DS.pdf) says it can be operated directly from integrated circuits. Would you still recommend the BJT?
I was actually just doing some further research on the 555 and stumbled across a monostable circuit with the output normally on. Does this make it simpler at all?