Normameter R1 bridge

Front panel of the instrument


This little Austrian Wheatstone bridge is powered by a 4.5 Volt flat batttery but sockets are provided for the connection of a mains operated power supply. Three sockets on the left hand side are intended for the connection of a buzzer device which can power the bridge with an alternating voltage. Using the buzzer and special headphones, the instrument is suitable for measuring fluid resistance, for determining the specific conductivity of electrolytes, for determining the titration end point, when major changes in conductivity indicate the completion of the titration, and for determining grounding resistances. A copy of the Technical Data sheet and a schematic (the resistor values given are those measured by myself)  are reproduced below.

This is one of a number of pieces of vintage test equipment offered to Gallery Oldham (Oldham Museum and Art Gallery) It was used by a local man who worked in cotton mills installing machinery. The labels indicate that it was probaly supplied by Croydon Precision Instruments Instruments (Cropico) to be used with a thermocouple to measure temperature in conjuction with the the conversion table attached to the back cover.