DESCRIPTION OF THE CHECKING MACHINE CIRCUIT. The circuit of
this machine is very simple. Basically there is only one circuit type
and this is operated 26 times once for each letter in the alphabet.
Considering the transformer as a battery and a starting point
the current for let us say the A key is traced as follows: when the A
key is depressed potential is placed on the stecker board section
(now replaced with straight wiring) thence to the first or right hand
commutator and drum. As the commutators are connected together in
sequence from right to left the circuit passes through the four drums
in the haphazard drum wiring to the U/W where the current is turned
to go through the drums again, this time from left to right and along
a different haphazard wiring set up to return to the first commutator
at any of the 25 remaining letters or commutator segments. Let us
suppose this letter is Z; the circuit now goes from the right hand
circuit and lighting the Z lamp. This Z is now interpreted as the
stecker of the letter at the other end of the link being tested.
MANNER OF OPERATION. The operation of the checking is fully
described in all its phases on pages 12 to 23 inclusive.
(AES Note: I have moved the last three lines of the previous original
page to the top of this page)