Spot Reflecting Galvanometer
To find extensive use as a DC null detector in wheat stone bridges and potentiometers. It is mains operated instrument or it can operate on 6 volt battery also. The light source 6 volt and 0.3 Amp. bulb. Construction: Built-in lamp and scale arrangement and housed in bakelite case. Scale is 150 mm long and is marked for both Centre and End zero use. To set light at any point on the scale. Sensitivity Control: The sensitivity controlled by a 2-Pole, 6-way switch. The switch positions are D, 1, 1/10, 1/100, 1/1000 and s/c. Direct Position (D Position): The switch correspond to the highest sensitivity with no internal damping in this position, movement is connected straight to the terminals without any shunts. X 1 (Position): In this position, one gets maximum sensitivity with near critical damping because the galvanometer movement is shunted by an internal damping Resistor. X 1/10, X 1/100, X 1/1000 Positions: The current sensitivity is reduced by an AYRTONMATHER shunt by x 10, x 100 and x 1000 with respect to x 1 range. S/c Position: The input circuit is broken and the movement is shorted for its protection in transit. Galvanometer X Damping X Sensitivity 100 ohms x 1000 ohms x 0.04 uA per mm 600 ohms x 7000 ohms x 0.04 uA per mm.