This system enables the basic properties of optical fibres to be investigated and the ideas then extended to demonstration of some of the principal scientific and commercial uses. The low-cost plastic fibre may be cut to any desired length with a sharp knife and does not require any special terminating devices. It is also completely non hazardous. The system comprises a transmitter, a receiver (both built onto P.C. boards 120 x 150mm) and a 25m length of optical fibre. 20m of this is intended for speed of light determination and long distance communication demonstrations.
Transmitter
• Light source: High intensity red LED, output at 630nm.
• Modulation: Internal or external. The internal modulation source is a 300kHz oscillator (normally used for the speed of light experiment).
• External modulation input: 0 to 2V d.c. linear, up to 5V digital, or a.c. coupled via external capacitor (not supplied).
• External modulation frequency range: d.c. to greater than 300kHz, TTL compatible.
• Monitor output: 0 to 2.5V, for connection to an oscilloscope, or to measure the LED operating current.
• Power requirements: 5 to 6V smooth d.c., reverse polarity protected.
• Terminations, Optical: simple push in connection for 1mm diameter optical fibres.
• Terminations, Electrical: all connections by both 2mm and 4mm sockets.
Receiver
• Input: Solid state photo-detector.
• Output 1: d.c. to greater than 5kHz, for connection to meters etc. and general analogue audio signals.
• Output 2: High speed digital output, 0 to 5V from below 20Hz to above 300kHz.
• Controls: Two, providing for zero-set and gain on output 1.
• Power requirements: 5 to 6V smooth d.c. reverse polarity protected, (the transmitter and receiver may share the same power supply if desired).
• Terminations, Optical: simple push-in connection for 1mm diameteroptical fibres.
• Terminations, Electrical: all connections by both 2mm and 4mm sockets.
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