The AC power source in the previous lab was created with a mechanical device. This type of alternating signal can also be created with a software app for a tablet or phone. WaveLab is an app that is illustrative of many software applications of this kind. It allows the rate at which the signal moves back and forth to be controlled, from one or two times a second to hundreds of times per second.
Now you will power the linear motor using digital control. Most modern motors are infact controlled through digital control. If you are using the PASCO interface in your classroom, set it up along with your linear motor.
On the PASCO, there are two output jacks for the banana cables. Plug two cables into the jacks, and connect the other ends to your linear motor.
Open up the SparkVUE software that comes with the PASCO interface. You will need to setup a new program. Select “BULD” and then select the Function Generator option. Your screen should look like the image on the left. Now, you will have two controls. Voltage and Frequency. Set the frequency to one hertz. Turn the function generator on, and adjust the voltage until the motor begins to move. Now adjust the frequency. What happens to the motor as you adjust the frequency?
If you are not using the PASCO interface in your classroom, you can use an audio amplifier and software from your computer to drive the linear motor.
You will need to plug two banana jacks (with the ends cut and stripped to expose the wire) into the speaker jacks on the amplifier. Additionally, you will need to plug in an audio cable into the amplifier. The other end of the audio cable will be plugged into the speaker port on your computer.
