user2812: I've taken apart an old range finder (see photo here). It uses a circular, seemingly gold-plated, two-wire sensor that I'd like to re-use in an Arduino project.
I'm looking for a datasheet of the sensor and/or a circuit-diagram. Any help is welcome.﻿

user3219: The big circular parts likely is ultrasonic transducer as used in instant camera. 
http://www.uoxray.uoregon.edu/polamod/
https://www.google.com/?gws_rd=ssl#q=polaroid+ultrasonic+ranging+module&revid=399558007&safe=off
Working principle is same as modern unit, easily available at a few US dollars. The transducer does NOT work by itself, needs the associate PCB to work.

2812: <p>I've taken apart an <a href="https://plus.google.com/111652317143259686566/posts/75TraxED8bg" rel="nofollow">old range finder (see photo here)</a>. It uses a circular, seemingly gold-plated, two-wire sensor that I'd like to re-use in an Arduino project.
I'm looking for a datasheet of the sensor and/or a circuit-diagram. Any help is welcome.﻿</p>
 3219: <p>The big circular parts likely is ultrasonic transducer as used in instant camera. </p>

<p><a href="http://www.uoxray.uoregon.edu/polamod/" rel="nofollow">http://www.uoxray.uoregon.edu/polamod/</a></p>

<p><a href="https://www.google.com/?gws_rd=ssl#q=polaroid+ultrasonic+ranging+module&amp;revid=399558007&amp;safe=off" rel="nofollow">https://www.google.com/?gws_rd=ssl#q=polaroid+ultrasonic+ranging+module&amp;revid=399558007&amp;safe=off</a></p>

<p>Working principle is same as modern unit, easily available at a few US dollars. The transducer does NOT work by itself, needs the associate PCB to work.</p>
