Nexus Research Group - Super Mouse data logger

Mouse Sensor Data Logger!

by Michael and Christine Fenton 2003

What is a Data Logger?

A data logger is a device that detect information from sensors such as light, voltage, speed, etc. Most High School physics labs have some kind of data logger equipment. The software usually costs over $500, the sensors cost about $300 each, and the interface box costs around $700, allowing a computer to record information and graph results.

What can you find out using the SmartMouse Data Logger?

You can find out:
- Is a force really needed to keep an object moving?
- What is the difference between velocity and acceleration?
- What forces are experienced in collisions and why should we wear seat belts?
- What is the acceleration due to gravity on Earth?
- What is my reaction time?
- What kind of plant or animal behaviour have I recorded?

How can I build my own sensor system and save $$$?

For those of us with little or no money to spend on the commercially available data loggers, here is a simple and effective home made sensor system using an old computer mouse...

Fig. 1. Socket (B) wired in parallel to mouse button (A)

Carefully remove the cover from a mouse. Solder a 3.5 mm mono audio socket (B) in parallel with one of the mouse button switches on the circuit board (A).

Attach a length (2 m) of inexpensive speaker wire to a 3.5 mm mono plug.

You should now be able to insert the plug into the socket and temporarily touch the two ends of the speaker wire together to create a short circuit in the mouse.

If you are running Windows the computer will interpret this as if you had clicked the mouse button. You now know everything is wired OK. Replace the Mouse cover.

Connect a magnetic reed switch (A) to the end of the wires of the 3.5 mm plug (C). Insert the plug into the socket (C) on the mouse and the computer will now sense whenever the magnetic reed switch is activated.

For free-fall experiments I connected a momentary action push button switch (B) in parallel with the magnetic reed switch (A).

An object with a magnet attached triggers the magnetic reed switch as it passes. The object falls and finally presses on the button switch (B).

The SuperMouse software records the time interval between switches A and B activating.

Fig. 2. Magnetic switch (A) in parallel with button switch (B) wired to plug (C)

Fig. 3. Multiple magnetic switches (A) in parallel to button switch (B) wired to plug (C)

You could add as many switches of various kinds as you wanted to the 3.5 mm plug.

Here multiple sensors record the time an object falls a predetermined distance between the sensors.

You could set up a similar apparatus for horizontal motion along a benchtop.

An easy adaptation is to set up a pendulum and record the period of the swing to determine g.

A turntable with a magnet or two glued on can trigger the magentic sensors if carrying out an angular momentum or acceleration experiment.

You can easily write a very simple program to save the data collected or process and display the results. SuperMouse is an example.

Things to try:

Our SuperMouse 3.0 software will even run on an old 486 computer (like those donated by Westgate) and does NOT require Windows!

1. Use the SuperMouse and a pendulum to determine the value for g, the acceleration due to gravity on Earth. The text book states this as 9.8 ms^-2. Can you get within the range of 9.2 - 10.4 ms^-2? Download these experiments in PDF format.

2. Use the SuperMouse to record the activity of a pet (eg, a real mouse!) and determine if it is nocturnal (our SuperMouse 3.0 software has a frequency function for this sort of biology project).

3. You can easily write your own software in BASIC, Visual BASIC, whatever! Just think carefully what type of experiment you are carrying out:

Frequency (how often)	Period (how long)
Log the number of activations within a set time period.	Log the amount of time from one activation to the next.
Monitor animal behaviour/activity	Measure velocity
Determine frequency of an oscillating spring	Calculate acceleration and determine forces
Investigate rotational inertia using a turntable	Determine your reaction time
Investigate angular momentum	Calculate the value for g using a pendulum
	Calculate the value for g using a falling object
	Investigate momentum in collisions

Some points to note:

1. Why bother writing complicated graphing routines? All you have to do is dump the data as an ASCII text file (make it COMMA delimited or SPACE delimited) onto the hard drive then use EXCEL to import the results. You can then clean up your data and make really professional looking graphs you can paste into other applications as well!

Here is some example QBASIC code to open a data file and write data as a Comma Seperated Values (CSV) text file that is recognised by EXCEL:

OPEN DataFileName$ FOR APPEND AS #1

PRINT #1, "Trial, Period"

PRINT TrialsCompleted%; ","; TimeDifference$

CLOSE

Where DataFileName$ is the name of a .csv file you have typed in (eg, pendulum.csv), TrialsCompleted% is an integer variable the computer has kept track of, and TimeDifference$ is a string variable recording, in this case, the period of a pendulum swing.

2. Need some experiments for senior physics students? Download these gravity experiments in PDF format.

3. You can use the SuperMouse on the Air Track too!

Our SuperMouse 3.0 software will even run on an old 486 computer (like those donated by Westgate) and does NOT require Windows!

OTHER DATA LOGGER ALTERNATIVES...

RIGEL - Real-world interactive games and electronics link. A SMARTboard capable interactive real-world game interface, datalogger and proces control system. Suitable for teaching, research and industrial applications.