Standard PSU →
The one shown here is the TEMPEST
variant, marked БПК-125,
which has thusfar only be found
in combination with Fialka machines in Poland, which is why it
is sometimes referred to as the Polish Fialka PSU. Other countries, such
as the former DDR, used the standard PSU.
The TEMPEST PSU measures about 28 x 19 x 17 cm and was designed especially for
use with Fialka. It is suitable for both Fialka models (M-125 and M-125-3).
It is connected via three cables:
one at the front for connection to the
110V or 220V AC mains, and two at the rear.
The two cables at the rear should both be connected to the Fialka.
A thin cable provides the necessary 24V DC voltage for running Fialka,
whilst a thick cable connects the PSU to the 5-bit digital output at
the right side of the Fialka. This connection to the digital data output
is mandatory as it activates the
TEMPEST measures inside the PSU.
This is achieved by a small switch that is mounted in the data connector.
Without this connection, Fialka will not run.
All controls of the TEMPST PSU are at the front panel. The switch at
the bottom left is used for selecting the correct mains voltage range
and for switching the device on or off. A ring with an
excentric disc protect this switch against setting it to the wrong
voltage (more about this below).
Above the mains voltage selector is a 3-position primary voltage
adjustment and - above that - the 10-position secondary voltage selector.
Above this selector are the primary (3A) and secondary (5A) fuses.
These are typical Russian fuses that may be a bit hard to obtain.
The section at the top is for checking the functions of the PSU.
When the PSU is in use, the meter at the top center should read
between 50 and 60. This indicates a nominal output voltage of 24V DC.
The two check switches are used for checking the currents and
the TEMPEST feature.
The STROBE light, to the right of the meter, is also for checking
the TEMPEST feature (more below).
The socket for connection to the mains is at the front right
of the PSU. All other connections are at the rear, where four
sockets are present. The leftmost one (marked МАШИНА I) is the
24V output for Fialka. The rightmost one (marked МАШИНА II)
is for connection to Fialka's data output. If Fialka is normally
connected to a transmitter or telegraphy device, that device
should now be connected to the center socket at the rear of
the PSU marked ВЫХОД (output).
Although it may seem unnecessary, the data socket
(marked МАШИНА II) must be connected, as otherwise
the machine will not work. This is done to ensure the use
of the TEMPEST feature (see below).
An extra 24V DC output socket is
available at the bottom. This 2-pin socket can be used for
connection of an extra device, such as a work light
or an extra Fialka machine. In the latter case, the TEMPEST features
are not used for the additional machine, of course.
In order to use the TEMPEST PSU in combination with a Fialka machine,
a minimum of three cables are needed: a mains power cable, a 24V DC
cable for feeding Fialka, and a data cable.
These cables are usually stored inside the
cable storage compartment
at the right side of the PSU.
The hinged lid to the cable compartment
is held in place by two screws that can be
loosened by hand or,
if they are really tight, with the aid of a
screwdriver. If the cables are present, it may be a bit difficult
at first to get them out of the storage compartment as the cables
will be rather stiff.
Be carefull with these cables as they might have become fragile
after all this time. Once you got them out of the storage compartment,
it is probably best to leave them out and store them separately with
the PSU in the future. This will protect the cables against too much
For safety reasons, it is advised to thoroughly check the
mains power cable
before connecting it to the mains. As the cable is rather old,
the insulation of the internal wires may have become brittle and might have to
be replaced. Use the mains cable only if you are certain that it is safe.
The data cable
is something truely special. It is a vital part of the
TEMPEST feature of this PSU and allows the PSU to monitor the 5-bit data
stream created by the Fialka. One side of this cable holds a
10-way data connector
that fits the digital data output
at the right side of the Fialka.
A switch, that is mounted at the base of this plug, senses whether the
plug is placed in the socket and activates a relay inside the PSU.
This relay switch the 24V output of the PSU on. This is done
to ensure that the cable is in place and that the TEMPEST safety measures
At the other end of the data cable is a rather
large circular plug
that should be connected to the МАШИНА II socket at the rear of the PSU.
If this cable is missing, it is advised to build a
suitable alternative before continuing.
The remaining cable
simply connects the 24V DC output of the PSU
to the 24V DC input at the left side of the Fialka.
The PSU can be placed either to the left
or to the right of the Fialka.
It can also be placed behind the machine or on a shelf.
The various cables should just be long enough for that.
Before connecting the power supply unit (PSU) to the Fialka, you first
need to check the voltage settings on the device, and adjust them if
necessary. First check the setting of the ВЫКЛ switch at the bottom
left of the front panel and ensure that it matches your mains AC voltage
(127 or 220).
This switch can be altered by unscrewing the ring
and rotating the excentric disc
at the center by 180°. The centre setting
of this switch turns the PSU off. For most European 230V networks,
you should set this switch to 220V.
If your mains voltage is slightly lower or higher, you may compensate for
this by setting the toggle switch at the center to МЕНЬШЕ (less)
or ВОЛЬЕ (more).
For 230V networks - which is common in Europe nowadays -
this switch should be set to МЕНЬШЕ (less - i.e. the leftmost setting).
It prevents the mains transformer from going into saturation.
Ensure that the PSU is switched OFF
(ВЫКЛ set to the centre)
and connect the Fialka to the two sockets at the rear of the PSU.
A thin cable
connects the PSU socket МАШИНА I to the
24V DC input
at the left side of the Fialka.
A thick cable connects PSU socket
МАШИНА II to the
at the right side of the Fialka.
Ensure that the Fialka itself is switched off at this stage.
Now connect the PSU to the mains
by supplying the mains
AC voltage to the СЕТЬ socket at the front right and then turn
the PSU on (leave Fialka off at this stage). Ensure that the meter
at the top
shows a reading between 50 and 60.
If it is higher or
lower, use the rotary switch at the centre to adjust the voltage.
When it is within the required range, it is safe to turn the Fialka on.
At this stage, the motor of the Fialka should start running.
If it doesn't, there might be a special condition: the motor
may be blocked (engine grease has dried up), one of the fuses
in the Fialka may be broken, or
one of the fuses of the PSU may
be blown. When the Fialka is running, the primary current within
the PSU can be checked by pressing (and holding) the
on the PSU, marked КОНТРОЛЬ I. The meter should
show a reading between 40 and 90.
Likewise, the secondary PSU current can be checked by pressing
(and holding) the rightmost push-button,
marked КОНТРОЛЬ II.
It should give a reading between 80 and 90. Now press a key on
the Fialka keyboard, whilst still holding down КОНТРОЛЬ I
or КОНТРОЛЬ II. The STROBE light to the right of the meter
should flash briefly. If it doesn't, there might be something
wrong with the thick data cable
between the Fialka and the PSU. The STROBE light indicates the
presence of the STROBE signal on the data cable and confirms
that the TEMPEST circuit is operational.
The circuit of the TEMPEST PSU is extremely complex and difficult
to trace. Roughly speaking we can device the circuit into three
functional blocks: the transformer, the stabilizer and the
TEMPEST circuit. This is illustrated in the simplified circuit
At the left is the mains transformer,
which has several taps
at the primary side in order to adjust it to the local mains
voltage. The output voltage can further be adjusted with a
10-position rotary that selects the appropriate secondary tap.
After rectifying the secondary voltage, a stabilizer circuit
converts the raw 29V DC into a more stable 24V DC that is suitable
for driving Fialka.
The block at the far right is the TEMPEST circuit. It consist
of five identical sub-circuits; one for each bit of the 5-bit
digital data output of Fialka. The simplified circuit diagram below
shows how it works on one of the bit-channels. To the left
of the dashed line is the output circuit of one of the data bits
of the Fialka. This circuit (T1) drives the printer/puncher
To the right of the dashed line is the input circuit of a single
bit of the the PSU. Whenever the solenoid (S1) is activated,
is not conducting and the dummy-load resistors are not driven.
As soon as S1 is realeased (i.e. the bit is not driven),
T2 starts conducting and the dummy-load resistors are activated.
There are five identical circuits;
one for each bit.
The value of the dummy-load resistors
is choosen carefully,
so that they the circuit draws the same current as the solenoids.
As a result, the PSU will not only supply a constant voltage,
but will also consume a constant current. This way, an eavesdropper
can not obtain any valuable information by tapping the mains
power line (TEMPEST).
The interior of the PSU can be accessed by removing the two side panels
and the bottom panel. The side panels are held in place by two screws
at either side of the PSU. After
removing the two screws, the side panel
can be removed. Other other side panel can
be removed in the same way.
At the right side,
the grey mains transformer is immediately
visible. Below the transformer is an array of five capacitors
that are connected in parallel. Some of the power transistors are
mounted to the rear panel for sufficient cooling.
The other side of the PSU holds a large brown printed circuit board
(PCB) that contains the electronic circuits. Apart from the 24V
stabilizer, this board contains the TEMPEST circuit. The dummy-load
resistors are visible as an
array of resistors
at the top edge of the board. The actual
TEMPEST circuit itself
is located in a corner.
Also on this PCB is the
STROBE sensing circuit
that enables the TEMPEST circuit
whenever the user presses a key on the Fialka keyboard.
This circuit also drives the STORE check light,
to the right of the meter a the front panel.
In some of the circuits, 2TC613 ICs are used .
Each of these ICs contains four transistors, They belong to
one of the first generations of Russian ICs.
Behind the transformer is a relay that switches the 24V output.
It is activated by the data connector switch.
One of the most important cables is the
thick data cable, that
connects the 5-bit digital output of the Fialka to the PSU, to
that it can monitor its activity and enable any of the internal
dummy-loads. If the cable is missing, use the diagram below
to create an alternative:
The data connector at the right is shown looking into its pins.
It has 10 pins, all of which are wired. The numbers at the end
of the arrows correspond with the numbers of the pins of the
large circular connector. Please note the switch that is built
into the base of the data connector at the right. It will be
activated (i.e. closed) as soon as the plug is inserted into the
data socket of the Fialka. It is wired to the large connector
via two additional wires (18 and 19).
For completeness, the pinout of the data socket at the right side
of the Fialka is given here as well. It is identical to the data
socket at the rear centre of the PSU and is wired straight through.
As the data socket on the Fialka will be used by the PSU, any
external device (e.g. a transmitter or a telegraphy device)
should be connected to the PSU instead.
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© Crypto Museum. Created: Monday 12 May 2014. Last changed: Thursday, 07 January 2021 - 15:14 CET.