For demonstrating & using a fibre optic data link
The transmitter unit contains all the electronics for producing the modulated light source as well as an easily accessible PP3 battery compartment. A choice of modulation is available.
A variable frequency audio tone in the range 1- 1KHz and a 250 KHz square wave for speed of light investigations which is brought out to 4mm sockets for monitoring on an Oscilloscope.
The receiver is in a similar case and contains a variable gain amplifier with integral loudspeaker as well as direct monitoring sockets for an oscilloscope.
The wavelength used is in the visible red part of the spectrum and with the modulation set at 1Hz the pulsing beam can be easily seen.