Newport Laboratories 200A-3 digital panel meter (1972)
This is a 3,5 digit digital panel meter
with nixie display.
I have two of them and still thinking of an application.
The 200A-3 is a digital panel meter with a 3.5 digit display.
These meters are built for 115V mains.
The previous owner had wired them in series
for use on 230V mains.
He also had found the input.
I bought these meters on a swapmeet.
When I tried them at home, they seemed to
At least, the displays light and say “000”.
I carefully dismantled one of them to see how it was built.
It consists of two boards.
The nixies, counters, decoders and control circuits
live on one board.
The power supply and analogue circuits are on the other board.
The boards are connected by
a ribbon cable of about 8 leads, carrying
power and a few signals.
A look at the two boards, hinged open.
It has 3 Amperex ZM1000 nixie tubes, “Made in Holland”.
Interesting, isn't it?
A neon lamp is used as a leading “1”.
It uses industrial-grade IC's by Fairchild in
Cerdip (ceramic dual in line package) packages.
The logic ciruitry is built using
TTL (Transistor-transistor logic) and
some DTL (Diode-Transistor Logic) IC's.
Two SG3250T opamps are used for the
analogue part of the A/D converter.
The production codes on the IC's date these meters in 1972.
The A/D converter seems to be quite simple.
The readout is not latched, so that
the counting of the A/D converter can be seen.
At least, so I presume, because I haven't put
any signal to the input.
A look at the two boards, from the other side.
These are nice pieces.
Now I need to think of a purpose.
Some power supply, or maybe the internal
temperature of a steampunk-style computer case or...