Extech Instruments Substitution Box

The Extech 380400 Resistance Decade Box is very popular for product design testing and calibration because it can be substituted into a circuit and function in the place of any component with a standard value easily. Alternatively, it can be used to identify the best value for circuit operation then read that value from the switches. Then, a resistor of the size indicated by the decade box switches can be put into the circuit.