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April 21, 1936 

(Following is a more detailed description or invention made on 

March n, 1936) 

Modification No. 2 in Converter Type M-134-T-l 

(U.S. Patent No. 2,028,772 of Jan. 28, 1936) 

1. Instead of the cipher-key or tape transmitter (Fig. 1 of 

U.S. Patent No. 2,028,772; item 26), employ a set of juxtaposed 

cam wheels to operate the set of contacts corresponding to the 

make and break contacts of the cipher-key tape transmitter. There 

may be 5 cam wheels, or there may be more than 5, interacting to 

give resultants in the Baudot 5-unit code. The cam wheels bear 

cams for opening and closing circuits; the peripheries of the cam 

wheels bearing different numbers of cams, these numbers being prime 

to one another. The cam wheels are individually rotatable upon 

separate shafts and are driven stepwise by some power source. Thus, 

a cipher key of enormous length can be provided for ciphering purposes. 

2. The Baudot combinations set up by the cam wheels are ca.used to 

interact with Baudot combinations set up by keyboard operation, to give 

resultants also in the Baudot code. There will be 32 possible resultants 

and hence provision must be made for 32 indications. 

3. Instead of employing a commutator of the type shown in Fig. 1 

of U.S. 2,028,772, let there be a rotating drum herein called the "indicator wheel", carrying on its periphery 32 combinations of projecting 

and nonprojecting pins in sets of 5 tranversezy to the drum. (In this 

respect the present drum is similar to the commutator of U.S. 2,028,772 

@'pp roved for Release by NSA on 10-09-2013 pursuantto E .0. 1352a 
REF ID:A39609 

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except that the former has all .32 of the Baudot combinations instead 

or only 26 combinations representing the alphabet, as in U.S. 2,028,772.) 

4. The pins on the rotating drum or indicator wheel are for the 

purpose ot opening and closing circuits to interact with the resultants 

explained in Par. 2, just as is the case in the comparison circuit of 

U.S. 2,028,772. But in the present invention,the comparison circuit, 

instead of stopping the drum in the selected position, merel.1' determines 

the exact moment at which either a lamp will be lighted or a letter will 

be printed. In this respect this invention is exactl.7 similar to that 

described in Modification No. l to Converter Type M-134-T-l, dated March 

12, 1936. The cipher resultants will embrace 32 characters in the present 

case. 

s. A connection changer, tor additional keying purposes, may be 

interposed in the comparison circuit. 

6. Instead of fleeting indications by lighting the lamp 6, it is 

possible to have a printed record. This can be accomplished by mounting 

a type wheel on the rotating drum and causing the comparison circuit to 

actuate a print-stroke magnet at the proper instant, to drive a paper 

tape against the letter presented at that instant and then to advance 

the tape one space. The characters recorded would comprise the 26 

letters plus 6 other characters to represent the extra permutations. 

(J,\1 W ~~.~ .. L - 't,ai . ..,CJ-.VJ~ 

William F. Friedman 
= 

REF ID:A39609 

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Warch ll, 1936 

~oditication in Converter Type I:.L-134-Tl 

(U. S. Patent 2,028,772 of January 28, 1936) 

1. Instead or the cipher-key or tape transmitter (Fig. 1, u. s. 

:tat. of' reference, element 26}, employ a set or five juxtaposed ca~­

bearing rotating wheels to operate the set or contacts corresponding 

to the l'!lake and break contacts or the cipher-key trans1:iitter. The 

ca.:r.-baaring t1heols bear ca.as tor closing contacts; the periphery or 

each 'tlheel bears a dif'f'erent number of cB.llls, with varying nw."lbers of' 

constant-length intervals between adjacent caDs. 

2. The 5 cam wheels can set up 32 per1.:l.utations or open and closed 

contacts. Therefore, the co·.::unutator ~heel must have 32 stopping ~ositione. 

3. Instead or a COl?l.mutator or the type sho1m in Fig. l or u. s. 

2,028,772, let it consist of a circular band divided up into 32 segments 

or transparent or translucent material, on which the characters are 

painted or printed. 

4. A light source is located mthin the band, and is so shielded 

that its light cill be visible only through an aperture in a box enclosing the entire uheel. 

s. The successive letters or characters ~ill be illUlilinated and 

seen through the aperture on stopping the band at the selected position. 

6. The five cam wheels are individually rotatable on the shaft, 
.•, . - • Olt 

REF ID:A39609 

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tor key-setting purposes, but once set and locked in position the 

whole asse~bly steps forward once per depression of the keyboard keys. 

7. Instead of having only 5 ca.m wheels, a set of 10 or 15 

(multiples or 5) can be used, the interaction giving 5-unit resultants. 

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