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Mini Corder E-120
TI-671/692
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Although the set looks like a dictation device, or dictaphone,
it has some characteristics that makes it more suitable for covert
operations. It is built with first class electronic components and is housed
in professional metal enclosures.
The miniature recorder is battery powered, but the batteries are housed
in the remote control unit (RC), rather than in the device itself.
This makes it easier to replace the batteries as the RC is usually carried
in the hand.
Both devices are marked with identification numbers (TI) of the
Czechoslovakian Ministry of Internal Affairs.
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In order to minimise the size of the equipment, the smallest device is
for recording only. It can not be used for playing back or winding the tape.
As a result, it is small and lightweight, making it easier to conceal it
on the body. The player is a desktop device that can be used for winding
the tape and playing it back. It can not be used as a recorder. Judging from
the date codes on some of the components, this unit was manufactured in
1977 or 1978. It is likely that several thousand units were made.
According to surviving Stasi documents, it was no longer
available in 1988 [2].
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Most of the components inside the devices are made by Tesla.
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The use of the Mini Corder 120 by the Polish Police is confirmed
in a Power Point presentation about an exhibition with objects from the
collection of the Polish Police Museum in Warsaw [1].
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The diagram below gives a quick overview of the controls and connections
on the two devices. The recorder has only two switches: one on the remote
control unit, and one on the recorder's body. When a tape is in place and power
is turned ON, it will start recording immediately.
Once recorded, the tapes can be played back in the large desktop player,
or transcriber as it was called. It has a small control stick to
(re)wind and playback the tape. Furthermore it has an optional speed control.
The player is powered by internal batteries or by the supplied PSU.
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E-120 Mini Corder
TI-671 - ECHO
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The recorder measures just 84 x 65 x 18 mm and weights 174 grams.
It is housed in a thin impressed eloxed aluminium enclosure with a
professional look and feel. It is wired permanently to the microphone
and to a black 2-pin male connector, to which the power should be applied.
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The overall build quality suggests that it is not a consumer device.
The batteries are not housed inside the recorder itself, but reside in
a plastic remote control unit that measures 54 x 35 x 14 mm.
Four thick button-type batteries are needed
for a total of 6V. Power is controlled by means of a switch
inside the remote control unit (RC).
In covert operations, the recorder is often hidden under the operative's
clothing, whilst the RC is held in the hand with its cable running
through the sleeve, or in another convenient place. This way, the recording
can be started and stopped.
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A second RC is supplied to allow quick replacement of the batteries without
the need to uncover the recorder. Sound is recorded onto a special
tape cassette that is similar (but not identical)
to a Philips Mini Cassette [4]. Before starting a recording session, the tape
has to be erased, using the supplied eraser,
and rewound to the beginning, using the rewind feature of the
U-120 player.
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Once the tape has been installed
and the lid is closed, the recorder
is enabled by sliding the switch on the
recorder's right side
to the ON position.
This engages the tape transport system and places the tape before the
recording head.
Once the RC is loaded with batteries and
fitted to the black 2-pin plug,
recording can be started by sliding the switch
on top of the RC
to towards the embossed dot.
Sound is picked up by a small sensitive
Sennheiser MM-26 microphone,
shown in the image on the right, that is fixed-wired
to the recorder via a thin grey shielded cable.
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The tape can record 60 minutes of sound, after which it has to be turned
over. A few spare cassettes were usually supplied with every set.
Once the batteries were exhausted, they had to be replaced, either
by swapping the RC for a freshly loaded one, or by opening it and replacing
the button-type battery cells.
A miniature screwsdriver was provided
for opening and closing the RC.
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U-120 Transcriber
TI-692 - URAL
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The player is housed in a strong metal enclosure, constructed from 2 mm
thick eloxed aluminium panels. It measures 215 x 144 x 55 mm and weights
1.5 kg. The unit is powered by
five 1.5V AA-size batteries,
delivering a total of 7.5V (or 6V in case NiCd batteries are used).
Alternatively, the player can be powered externally by the supplied PSU
from the 120V or 220V AC mains network.
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At the left is a small lid below which the tape cassette should be installed.
The lid can be opened by
pressing the recessed button at the left,
after which the cassette can be entered.
A small stick at the front edge is used to control the tape flow,
shown here in the STOP position.
Before playing back a tape, it should be wound back to the beginning by pushing
the stick to the left. To start play-back, push it towards the cassette.
The recorded sound will be delivered through the built-in speaker at the
right, and the volume can be adjusted with the rightmost knob.
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As transcribing a conversion that has been covertly recorded with a concealed
microphone can be difficult and requires a high level of concentration,
it is possible to connect the supplied pair of stethoscope
headphones to the SP/EAR socket at the right side. Entering a plug into
this socket disables the internal speaker.
The U-120 Transcriber is also known by StB designator TI-692.
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Conversations are recorded onto a small cassette that measures
60 x 44 x 7 mm and that contains approx.
72 metres of ferro-magnetic tape. At a tape speed of 2 cm/s, this provides
a recording time of one hour (60 minues) on each side of the tape.
The total recording time is therefore 120 minutes, hence the names E-120
and U-120.
The width of the tape is 3.8 mm, which is exactly the same as that of the
standard Philips Compact Cassette and the Mini Cassette of the era [3].
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The remote control unit (RC) is actually the recorder's power source and
provides two functions. It can be opened with a miniature screwdriver
that is also supplied.
The RC has room for four cylindrical 1.5V button-type
cells that should be installed as indicated by the (+) and (-) symbols.
It delivers a total of 6V DC.
A small blue micro-switch controls the supply to the recorder.
It is operated by a sliding knob
on top of the RC, and can easily be
operated with one hand.
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A sensitive high-impedance microphone such as the one shown here,
was supplied with each E-120 recorder. It was most likely manufactured by
Sennheiser in West-Germany and was imported via clandestine channels.
It was usually wired permanently to the
body of the recorder by means of a a thin grey shielded cable.
In practice, small connectors were often inserted in the cable to make it
easier to conceal the parts on the body, and to repair or replace the
microphone if necessary.
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This miniature screwdriver was supplied with each E-120 recorder in order
to get access to the battery compartment inside the remote control unit.
It can also be used to get access to the
interior of the recorder in case it
needs cleaning or servicing, for example to replace the thin rubber
driving belts.
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The U-120 player is usually powered by five internal NiCd batteries of 1.5V
each, that provide a total of 7.5V. It can also be powered externally by
connecting the supplied PSU to the DC 6V socket on the right side of the
player.
The black circle on top of the PSU is the voltage caroussel, that allows
selection between 220V and 120V AC mains networks.
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Magnetic recording tape has to be fully erased before a new recording
can be made properly.
Normally, this is done in the recorder by means of a separate
erase head that writes a high-frequency bias signal onto the tape.
In order to save space, power consumption and weight, the erase head has
been omitted from the recorder. As the player has no facilities for erasing
the tape either, an external tape eraser is supplied with the set. When
pressing the black button, it provides a strong magnetic field that will
erase any tape placed under it.
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Transcribing a covertly recorded conversation can be quite difficult and
requires a high level of concentration. Audio can be played back via
the player's internal speaker, or through the light-weight
stethoscope earpiece shown in the image on the right, that was supplied with
each set.
The earpiece is connected to the SP/EAR socket at the
right side of the player.
When inserted, the internal speaker is switched off automatically.
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The recorder is built on a strong metal frame that is housed inside a
thin impressed eloxed aluminium enclosure that consists of two shells.
The upper case shell is held in place by four miniature screws: two at
the sides and two at the rear. Remove them to get
access to the interior.
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Inside the case is a sturdy enforced metal frame on which all mechanical
parts are mounted. The electronic parts reside in the rear section of the
unit and are kept to a minimum in order to save space, weight and energy.
Most of the electronic parts are contained a rectangular metal cases.
The mechanics are actuated by a small electromotor mounted at the
rear right, that is made by Maxon in Switzerland. It drives a
rubber belt that runs along the rear edge, which in turn drives
the flywheel/capstan and, via another belt, the pickup reel
that is visible here at the front left.
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When a tape is in place and the driving mechanism is engaged, the tape runs
between the capstan and a rubber pressure roller, to the left of the
recording head. Depending on the age and state, some of the rubber parts
may have to be replaced after several years, in particular the belts.
As ferro tape is used for the cassettes, it may be necessary
to clean the recording head regularly.
Note the disc with radial lines that is visible
on the capstan/flywheel in the image above.
It was used for adjusting the tape speed with a stroboscope, similar to
the turntables of the same era.
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The player, or transcriber, is build on a heavy metal frame,
housed inside strong metal enclosure, constructed from bended eloxed aluminium
plate. The top half of the case is held in place by four large bolts:
two at the front and two at the rear. After removing these four bolts and
also the knobs on the control panel,
the top half of the case can be removed
and the interior is exposed.
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All controls are mounted along the front edge of the metal frame, with the
battery level meter at the center. The left side of the chassis carries the
mechanical section, with the record head being the only electronic part.
It is connected to the amplifier board at the right, which is mainly built
with parts from the Tesla brand, which is why Tesla was
most likely the manufacturer.
At the center of the frame, prominently
visible in red, is the small electromotor
that actuates the driving gear via a rubber belt. Like the one in the recorder,
it is made by Maxon in Switzerland.
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The image above shows the mechanism as seen from the left rear of the
device. At the center of the screen are the pick-up and supply reels,
the capstan, the pressure roller and the playback head. At the top left is
the flywheel that is linked to the capstan via a rubber belt at the bottom.
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The image on the right shows a bottom view of the metal chassis. At the bottom
right is the battery compartment that has room for five 1.5V AA-size batteries.
At the top right are volume and tone controls, speed adjustment
and meter.
A small PCB is visible in the bottom left corner. It contains the motor driver
and is connected to the Maxon motor and to the speed controls at the
front panel. The circuit is factory calibrated to provide a constant tape
speed of 2 cm/s, but can be adjusted manually by turning on SPEED CONTROL
and setting the speed with the knob.
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This can be useful if a tape has been recorded on a mis-aligned or worn-out
recorder, or just to make it easier to transcribe a conversation, simply
by slowing it down somewhat.
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E-120 Recorder ECHO Recorder TI-671 Recorder Mini Corder Recorder U-120 Player URAL Player TI-692 Player Transcriber Player
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Tape length 72 m Tape width 3.8 mm Tape speed 2 cm/s Recording 60 min on each side
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We are currently looking for additional information about the Mini Corder
and Transcriber, such as a user manual, technical specifications and, if
possible, a technical manual. Also information about the use of these devices
is most welcome. If you have any information, please contact us.
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Any links shown in red are currently unavailable.
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© Crypto Museum. Created: Sunday 12 March 2017. Last changed: Tuesday, 03 July 2018 - 06:52 CET.
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