# Diode & transistor for a 3v motor?

I'm needing some help with which diode and transistor to use on a motor. I have almost no electronics experience except for tinkering. I'm trying a project which uses a 3v vibrating motor. I was told by a reliable source that I will need a diode and transistor in line with the motor to provide enough amperage for the motor

It mainly depends on the amperage of the motor (assuming you will be using a BJT).
<200mA:2N3904,<500mA:2N3704, etc.
As for the diode, I’m not sure.

Simple (on/off) driver circuit, scroll to bottom of page. http://gizmolab.pbworks.com/w/page/5686102/Arduino%20Tutorial%203%3A%20Motors

For low current operation pretty much any BJT transistor will work, as long as it is the right polarity (NPN / PNP).

As for the diode, you need one that will switch from forward to reverse and back as fast as possible. Schottky diodes are one of the best at this. There are specialised "snubber" diodes available, but there is no point in shelling out big bucks for one of those on a low voltage low powered circuit. They are mainly aimed at big industrial motors.

Lakes: Simple (on/off) driver circuit, scroll to bottom of page. http://gizmolab.pbworks.com/w/page/5686102/Arduino%20Tutorial%203%3A%20Motors

Simple but wrong.

The diode goes across the motor, its purpose it to absorb any inductive spike by diverting current at the time the transistor switches off (a motor is an inductive load) this protects the rest of the circuit from high voltages. The cathode of the diode (the marked end) goes to the +ve supply.

Here's the correct way (relays are also inductive): http://www.arduino.cc/playground/uploads/Main/relays.pdf

Yes, I noticed that, unusual to connect the diode across the transistor to sort the back emf that way.