Just a slight clarification...
The Ohm Meter should show a very low reading (from Zero Ohms, to possibly 100 Ohms), when the Circuit is CLOSED
i.e.: The Armature (Ringer/Arm) is at rest, and the Ringer/Arm is at the "Normal Not Energized" position.
The Contact on the Armature will be Closed in this state.
The Contact opens when the Armature makes contact to the Core/Coil Assembly (or slightly prior to making contact to the assembly).
With the Contact OPEN, the Ohm Meter should read Infinity / Off-Scale.
The Bell's operation is similar to an Automobile Horn's operation.
This type of Bell may be used on AC, as well as DC Systems.
FYI, the Ringer from an older Telephone Set oscillates the Armature via the 30 Hz, 100-105VAC Ringer Current from the Telco's CO.
In the Non-Energized State, the Armature is centered between the Two Bells.
With the Ringer Current applied, the Armature is driven Side-To-Side by the Alternating Magnetic Fields produced in the Core/Coil Assembly.
Since AC is applied to the Ringer, no Cutout Contacts are used or necessary.
If filtered DC was used, a Cutout Contact would be necessary.
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!