8th Inning

Introduction

Spin a motor, transistors and diodes

Motor - Included in your kit is a small DC electric motor. Electric motors are characterized by many different parameters such as:

• Voltage
• Current
• Torque
• Speed (rpm)
• Physical Size and shaft size

The one included can be run with as little as 1.5 volts (although very slowly) from a single cell battery up to 9 volts.

Motors tend to draw a lot of current when they start spinning. Once they are spinning this drop drastically unless they are placed under heavy load.

The maximum amount of current a small motor draws can be checked by hooking up a DC ammeter in series with the motor and physically stalling the motor shaft. Vise grips work well for this. Once you have the shaft secure, apply power and read the meter. This should be done quickly so as not to burn out the motor. Most motors can endure being stalled for a short time.

The start-up current is much more difficult to determine. I requires a meter that will record peek values or a storage oscilloscope. If your circuit can handle the maximum stalled current, then it will be able to handle the start-up current.

Transistor - Included in your kit a 2n2222 NPN (switching) transistor. A transistor can be thought as a voltage controlled switch. When voltage is applied to the base of a transistor, the transistor allows current to flow between the collector and emitter.

Components Needed

• Freeduino or Arduino or clone
• USB cable for Freeduino
• Freeduino development software - download here!
• Solderless Breadboard
• Hookup wire 22gauge solid