|STANDARD METALLIC CIRCUIT SWITCHBOARD, ENCLOSED PATTERN
No. 651 shown pictured to the right.
As supplied to the National Telephone Company, Ltd.
These boards are entirely enclosed, the wood-work being of very superior finish and
When operating, pulling the key forward puts the service hand micro-telephone into circuit, and pushing it backward puts generator current on to the calling cord. The central position of the combined key is the through position. A so called "ringing-back key" is fitted at the right-hand end of the key shelf, and serves for ringing on the answering cord if the calling subscriber should leave his telephone while the connection is being made. The equipment includes a hand micro-telephone, hand generator, and a ringing vibrator, which indicates to the operator whether the ringing circuit is in order.
These boards are so constructed that four or five of them can be fitted side by side,
sufficient space being left in the jack panels for fitting multiple jacks. The ring-off
indicators, which are bridged across the cords, are of the tubular iron-clad type, and
have a very high coefficient of self-induction.
Taken from the Ericsson Telephone Catalogue 1903
Last revised: October 11, 2019