Vintage Resistance Box by Philip Harris Ltd

£ 24.00
A resistance box contains a series of resistors of different values for the purpose of estimating and comparing various resistances. Usually the resistance is accurate to high precision, ranging from laboratory/calibration grade accuracy of 20 parts per million, to field grade at 1%.

The main application of the resistance box is to control the specific value of current to flow through a circuit. They offer a convenient way of selecting and quickly changing a resistance in laboratory, experimental and development work without needing to attach resistors one by one, or even stock each value. The range of resistance provided, the maximum resolution, and the accuracy characterize the box.

This resistance box was made by Philip Harris & Co Ltd in Birmingham and has resistance values of 1, 2, 2, 5, 10, 20, 20, 50, 100 for a maximum resistance of 210. There is also a key for infinite ohms. The wood is in good condition with no physical signs of damage. No keys included.