Decade Box

A Decade Box can be used for sensor simulation. The majority of temperature related sensors used on aircraft are resistance based. Resistance substitution can come in very handy for troubleshooting numerous systems. Window heat, cabin temp/control, engine indications, and overheat warnings are among some of the uses for a decade box.

Decade boxes can also come with capacitance and inductance substitution. I have found no uses for either.

Most resistance substitution boxes are not designed for power applications, ½ watt is the usual maximum power. Aircraft systems that use resistance for temperature measurement rarely exceed this value.

Just as a note: Caution should be followed when substituting a resistance for window heat sensors. The window can easily overheat and crack.

A great tool!

Haven't touched it as of late, but it's a great troubleshooter (simulator) for fuel tank temp, pack temp, window heat sensors...... just to name a few.

MD-11 brake temp also. If you don't have a new sensor to hang off the plug, the decade box will let you know if you've got a wiring or component problem.

Found a new use for the decade box. Fire loop system that would not test. Found open loop. Simulated the loop resistance with the box and the fire detection system tested correctly.