School Lab Resistance Substitution Box

School Lab Resistance Substitution Box

The tolerance of the resistance values is 5%.  
However, as is quite common, resistances can be closer to their nominal values.  
This switched compact unit contains 12 resistors, with preferred values in the range 100? to 470? mounted on a printed circuit in a robust black plastic box.  
Selection is via a rotary switch. External connections are by means of two 4mm yellow terminals, the colour indicating non-polarity.  
All the resistors have a maximum power rating of 1W.