science project (1 Viewer)

[EddieMata]

My son and I have made a basic talkline for his school science fair. It consists of : 2 phone sets, 2 jacks, 26' of telephone cable, and various battery holders for AA batteries.

We have been able to make it work fine, 6 volts (4 AA's) provides sound and voice but not best reception. 7.5 volts (5AA's) makes a clearly audible talkline and it improves with additional voltage.

The question is what would be a good way to determine or measure sound levels in order to differenciate voltages? I don't have a sound meter but am willing to purchase one if would assist with his results. Or any suggestions as to how to reflect the findings?

Any input would be appreciated!

THANKS!

Eddie

 

[DanielKellmii]

A sound meter is the only way that I can think of making an accurate unbiased measurement.

 

[Mike Voigt]

One approach:

1. Consistent source, e.g. CD, laptop, something like that.
2. Consistent measure, e.g. sound meter.
3. Compare various voltages to output.
4. Compare also to input.
5. Chart input as flat line (at top), output as curve approaching flat line, sound level as Y-axis, voltage as x-axis.

Should be pretty straightforward. And think of the sound meter as a multiproject tool - the other being your home theater !

Mike

 

[EddieMata]

THANKS for the suggestions ya'll have given!

I figured that I could use a tone from the digits on the phone set as a source.