Telecom or Communications Instruments
Psophometer Telecom Instrument
Wikipedia. I learnt some basic
instrumentation when i worked on above Instrument
at TMPL. TMPL as it was known decades back was in
Service and Sales of many Brands like Racal Dana,
Genrad, Data I/O and Electronic Production
Instruments - Telecom Test Equipment
This instrument had Auto Range for the Voltage
and dB meter. Very rare in those days. I did it
with a Window comparator and miniature reed
Psophometer from Germany - Here
is one that is fully analog, 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 was also made at TMPL, it 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.
This was in the eighties..
Future Landline Phones