The Caliper

Analog Out - A Free Function Generator
with Every LabPro!

One of the best features of LabPro is that it has flash memory, so its operating system can be updated to add new features. We are excited about the recent addition of analog output and a function generator. The frequency range of the function generator is 0.5 to 200 Hz. The current output is limited to 100 mA, but you can do some great experiments with this analog-output line. Here are some things we have tried:

• Drive a spring on a mass hanging from a hook glued on to a small speaker. You can explore resonance.
• Drive a stretched string from a hook glued onto a small speaker. When LabPro produces the right frequencies, you can produce a number of standing wave patterns.
• Study RLC circuits.
• Work with a sonometer to study vibrations in strings.
• Study the current in a small lamp driven by a varying voltage.
  See the sample graph below as one example.
• Control the DC voltage level as part of an experiment.

All of these experiments can be done using the analog-out signal directly from CH4 of LabPro (no amplifier is required). You can add an amplifier if you want to increase the current beyond 100 mA.

You need two things to use the analog-output feature of LabPro, and both are free:

• LabPro operating system 6.22 or newer. This is a free download from our web site.
• A program to generate the analog-output pattern. There are several options (all available on our web site):
  • calculator program for all of the TI graphing calculators
  • a simple Macintosh or Windows program that emulates a function generator
  • a LabVIEW™ VI (with source code) that you can use and modify

Future versions of Logger Pro software will have analog-output control included.

Voltage and current in a small lamp