• The system is comprised of 211 relays, their associated control circuitry, and a power supply.
  • The software uses an assembly language routine that constantly refreshes at a very high speed, preventing noise from energizing relays that should not be energized.
  • The relays are turned on and off in a sequence that removes current from their contacts first in order to minimize contact wear.
  • Diagnostic routines include complete tester calibration, individual relay tests, and ohm meter continuity tests.
  • The software automatically selects a proper filament voltage that takes into account the transformer, wiring, and relay contact voltage drops.
  • More details and pictures can been seen in the Photo Gallery.

    The database contains the data from all of the following card sets:

  • The complete "large" military card set
  • The Western Electric card set
  • The CA-4 adapter card set
  • The CA-5 adapter card set
  • The older tubes from the Model 123A card set

  • In addition, tubes are added to the database from time to time.  Or, you can add them yourself.  Click here for the current list.