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Traffic Tally 21

Single Inductive Loop Accumulator

The TT-21 has been replaced with the TT-51

Lightweight Single Inductive Loop Accumulator- Discontinued

The Traffic Tally 21 is a solid-state inductive loop detector counter for use with loops buried under the roadway. The counter will operate under all field conditions for over one year, on one set of batteries.

The TT-21 is a volume counter that holds one continuous count (accumulator), designed to give the user the ability to adjust the time delay.

To enable a counter to register one count per vehicle, a time delay feature is needed. A properly set time delay will eliminate multiple counts from trucks and trailers and still count a vehicle close behind.

Adjustable time delay
LCD (liquid crystal display)
Battery life of 12 months on "D" Cells
Fast automatic tuning
Standard external connections
Lightweight and compact


SIZE 8" x 8" x 5" (20cm x 20cm x 10cm)
CASE Aluminum, weathertight IP54
WEIGHT 9 lbs ( 4kg)
POWER 6 akaline "D" cell batteries. Battery life approx 12 months. Optional 110-120v AC power supply available.
TEMP RANGE -40°F to +160°F (-40°C to 72°C)
AUTO TUNING Automatic tuning to loops of 70-500 microhenrys
TIME DELAY 0.1 to 4 second adjustable time delay