NovRam, 460i and 460TC timers - What is the difference?

Older versions = NovRam 460

Mid 1990s, replaced by 460i with separate transformer

and the 460i design was used in 2011 to create the 460TC as a non-metered "Day" timer replacement for the mechanical 440 series of timers ( made from 1971-2011 ).
So the 460TC looks A LOT like the 460i, but it does not have the Sensor cable ( as it does not attach to any metering turbine .. and does not "count" the water used.

Old 440i and 440 timers.......................................... And the new 460TC ( which uses the 12 volt AC transformer used by all Autotrol Valves since 1995 )

460i Timer Assembly is available here:

460i_Timer_12_volt_60_Hz_# ap1040534

What is the difference between the 460i and the 460TC timer?

The 460i ( or older 460 NovRam ) Autotrol Electronic Metered Timer Assembly with Transformer for 12 Volt operation from your 120 Volt 60 Hz outlet.
Replacement for NovRam, 460, and 460i Timer Assemblies.

** Counts water ( via meter Turbine ) and regenerates based on water used ( dividing water hardness and iron level into capacity of the resin tank ).

460i_Timer_12_volt_60_Hz_# ap1040534

Complete 460TC ( 4001086 ) 12 volt AC 60 Hz ( timer clock ... NOT metered )
Regenerates on SET Day interval, as you "program" when "setting up".
It does not know or care how much water actually used.
It will run on the schedule you select ( every night, 2nd night, 3rd night, 4, 5, 6, 7 up to 99 days between regenerations ).

460TC_Replacement_Timer_Assembly_for_440_series_# ap460tc

So.... the only practical way to "switch" to metered operation is to replace the entire Valve Head.
see
255 / 760 Logix Complete Valve.
OR
If you have the 268 Performa, then Valve - 762 Logix Electronic 268 Metered Softener Control

But if you are replace the 460i with transformer, and have the 255 or the 268 valve, there are these "upgrade" kits.
Please note, they do NOT include the transformer, NOR the meter turbine, as these are "kits" to replace the 460i timer on the valve.. assumes you already have transformer and turbine.
And only works for the 255
here:
760 Logix 255 Upgrade Electronic replacing 460i series timer

or the Performa 268 valve,
here:
760 Logix 268 Upgrade Electronic replacing 460i series timer

So the BEST would be the complete metered ( regenerates based on actual demand - water used ) control Logix 760 on a complete new 255 Valve,
see:
Complete Valve Head 255 with 760 Logix Controller
OR
Valve - 762 Logix Electronic 268 Metered Softener Control
and
Old Valve Replacement Guide / Directions
and
740 and 760 Logix Timer Programming Instructions