Telecom or Communications Instruments

I learnt more about instrumentation and opamps when i worked with some instruments related to Telecommunications. Some telecom instrument prototypes also were made.

Psophometer Telecom Instrument

My exposure to T&M happened when i worked on the repair and calibration of such Instruments. This was before the year 1988 and later i remained in R&D Field of Test-Measurement  and Process-Control for many years.

This instrument Prototype had Auto Range for the Voltage and dB meter. Very rare in those days. I did it with a Window comparator and miniature reed relays (oki). (National Semiconductor and Intersil Chips)

Psophometer from Germany -

Below is a fully analog instrument, it must be using many transistors and probably Opamps. Maybe Hybrid Opamps, because this Instrument is after the Valve era but maybe before the Opamps came. By the size and front panel we can sense the period when this instrument was used.

Noise and Hum in Audio Circuits

Transmission Measuring Set

The one above is a Psophometer which was a true RMS auto-ranging AC dB level meter with weighted filters. The weighted filter has to resemble the audio response curve of the ear.

With a built in signal generator in dB settings it becomes a Transmission Measuring Set shown right below. This was in the eighties.

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