Teletype Monopulse Printer

© Brooke Clarke 2009

Photos
    Fig 0 Transmitter & Receiver 
    Fig 1 Front
    Fig 2 Front Door Open
    Fig 3 Inside Back
    Fig 4 Correct Paper Path?
    Fig 5 Inside Left Rear Terminal Strip
    Fig 6 Left Inside
    Fig 7 Right Inside
    Fig 8 Front Right Top "H-3" & Phase Adjustment
    Fig 9 Center of Transmitter
    Fig 10 Transmitter with center cover removed
    Fig 11 Underside of transmitter keyboard
    Fig 12 Keyboard out of chassis
    Fig 13 Motor - keyboard interface & Terminal strip
    Fig 14 Bottom of Transmitter w/Cover Removed
Background 
Description
Operation Description
Patents
Related
Links

Photos

Fig 0 Transmitter & Receiver
Teletype Monopulse Transmitter & M36 receiver
The keys are alphabetical:
- A B C D E F G H I J
1 2 3 4 5 6 7 8 9
K L M N O P Q R S T U V W X Y Z
(red key)

Fig 1 Front

Teletype Monopulse Printer
There is a chip in the paint shown on the printer
in the photo above, but my printer does not have
that chip, so they are different s/n.

Fig 2 Front Door Open

Teletype Monopulse Printer

Fig 3 Inside Back

Teletype Monopulse Printer

Fig 4 Correct Paper Path?

Teletype Monopulse Printer

Fig 5 Inside Left Rear Terminal Strip

Teletype Monopulse Printer

Fig 6 Left Inside

Teletype Monopulse Printer

Fig 7 Right Inside

Teletype Monopulse Printer

Fig 8 Front Right Top "H-3" & Phase Adjustment

x

Fig 9 Center of Transmitter

M36 Monopulse Teletype Center of Transmitter

Fig 10 Transmitter with center cover removed

M36 Monopulse Teletype Transmitter with center cover removed
Transmitter with center cover removed

Fig 11 Underside of transmitter keyboard

M36 Monopulse Teletype Underside of transmitter keyboard

Fig 12 Keyboard out of chassis

M36 Monopulse Teletype

Fig 13 Motor - keyboard interface & Terminal strip

M36 Monopulse Teletype

Fig 14 Bottom of Transmitter w/Cover Removed

M36 Monopulse Teletype


Background

Also known as the Teletype Model 36.
I've been told that these were used inside factories ( located on the same power gird as the transmitter) for internal communications.  They work using a type wheel (missing from this one - If you have one or know about them please let me know). 

The name comes from the idea that a single pulse defines each character, rather than using 5 or more pulses for each character.  The width of the pulse determines which character gets printed.  The key to this type of system is getting the transmitter and receiver synchronized.

Description

TELETYPE MODEL 36 (MONOPULSE) TAPE PRINTER SET
		The Teletype Model 36 Monopulse printer is a simplified printing telegraph device designed to supplement conventional Teletype apparatus in local circuit applications where printed message service is desired but where the traffic is not sufficient to justify the installation of standard Teletype equipment.  With Monopulse equipment, letters, figures and the
dash symbol (-) are alphabetically arranged. Selection is obtained through variations in the length of single pulse signals originating with the keyboard transmitting station. The set is particularly adapted for economical printed intercommunication services in offices, stores, banks, railway stations, factories warehouses, yards, etc., where all stations will be located
within a limited radius and have access to the same 115 volt 60 cycle power source. Monopulse equipment is not adapted for operation with other Teletype apparatus, and because of this and other limitations is recommended for local message service only. For general communications service over extended circuits see Teletype Model 14 and Model 15 printers.
______________________________________________________
YEARS PRODUCED & QUANTITY: 1942-1951 149 units
PRIMARY CUSTOMERS: Bell, General
CLASSIFICATION CODE: HP (Printer) HK (Keyboard)
MUSEUM CODE: 2C-24
TECHNICAL BULLETINS & SPECS: 16, D1-1
PHOTO NO(S): 690505-11
PATENTS:
LIBRARY REFERENCES: [ATT - Teletype Corporation; "Museum Equipment"; book 1, p33]

Printer Size & Weight

If you are used to TTY machines, this is much smaller!  It's 6" wide, 5" deep and 6" tall.
Weighs 7.5 pounds, but the line filter (or similar component is missing) maybe 8 pounds total.

Paper Tape

Width:     3/8"    core I.D.:  7/16"

Electric Motor

A.C. Synchronous Motor, Type RWC 2510, Volts: 110, Cycles: 60, R.P.M. 1800. No. 1015237, Watts: 9, Torque: 0.3 In. Oz., The Holtzer-Cabot Electric Co., Boston, Mass, U.S.A.
The worm gear reduces the speed by 15X i.e. 1800 RPM / 15 = 120 RPM or 8.333 ms per character.

Type Wheel

Mounts using two screws about 9/16" c-c.  The hole in the panel behind the type wheel is 1.45" dia.  There is a print hammer under the paper tape the snaps up to print the character.  The hammer

Solenoid

There is a solenoid on the back side related to driving the print hammer. 

Big Cap

Marked: 100295, VC429A, 1 MFD  220 VAC
Related to the motor.

Missing Component

Most likley an A.C. power line filter, see Electrical below.
If you know what's missing please let me know.

Electrical

The rear terminal strip is NOT connected to the front terminal strip.

Rear Terminal Strip (Motor)

The bottom three terminals are used.  The On-Off switch connects to the upper two terminals and the motor to the lower two terminals.  The cut wires are colored:
Black - upper terminal - A.C. Line
White - lower terminal - A.C. Line
Green - connects to the terminal strip mounting screw - chassis ground
The missing component may be a power line filter??

Front Terminal Strip (Solenoid)

Only the bottom two terminals are used.  They go to the solenoid which has it's two coils wired in series.  Resistance is 204 Ohms.  20 Volts (100 ma) will operate the solenoid.

Operation Description

[from "History of Telegraphy from the Teletype Museum"; Ransom D. Slayton, Consultant;1983]
"203. There was always the push to develop lower cost units for simpler systems. One such system was the Model 36 Monopulse.

"204. This operated much like some early stock tickers, with the line signal being an OPEN interval during which sending and receiving devices
rotated until the proper point was reached for printing the desired character. the Keyboard, at the left here, had its Keys mounted in a
circle, which was non-standard and took a bit of training by the operator. The sending contact was opened by depressing a key, and remained open until the selecting arm reached that key after leaving its rest of STOP position.

"205. Meanwhile, the selecting arm at the receiving Printer was similarly seeking the printing point. When the line closed, it was there, so the
printing hammer struck the rotating type wheel, printing the character. The Printer type wheel was inked, much as the old BLUE and GREEN code printers had been. The inking roller can be seen at the top of the printer, with the type wheel under it. then comes the printing tape, the supply roll of which is at the bottom. The printing hammer is just under the tape and print wheel, and moves upward to cause printing. The system was very simple and therefore low cost, but only a limited number were made. "
The early Baudot teleprinters held the selector with an electromagnet and at the start of a character released it allowing the selector to rotate.  It makes sense that this printer used a very similar technique, except here the circle is divided into 26 letters and 9 numbers (letter O doubles as the number zero).  The time when there's no current determines which character is going to be printed.  When the line is again connected the electromagnet is activated (causing the print hammer to strike) and when the transmitter and printer get to top dead center the rotation stops, ready for the next character.

Patents

Receiver

2249040 Printing Telegraph Apparatus, Louis M. Potts (Teletype Corp), Jul 15, 1941, 178/35 -
Monopulse  M36 patent 2249040 Printing Telegraph Apparatus
2367427 Telegraph Transmission System, Louis M. Potts (Teletype Corp), Jan 16 1945, 178/17A ; 178/17R  -

Transmitter

2173147 Telegraph Trnasmitter, Walter J. Zenner (Teletype Corp), Sep 19 1939, 178/79 ; 178/33R; 370/305 -

2219904 Telegraph Transmitter, Louis M. Potts (Teletype Corp) October 29, 1940, 178/79 ; 178/33A; 178/33MP -
Patent 2219904

 Related

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Links

Antique Wireless Association (AWA) -

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page created 17 Nov 2009.