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Wooden case by Peter Meijer, Germany
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Peter Meijer from Germany, has sent us pictures of the wooden box that he
created for his Enigma-E. But what's more, he found a clever way to use the
morse code sounder, without added an extra buzzer and he's come up with an
alternative circuit to feed the Enigma-E, for those who'd like to give it a try.
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Peter used the back of on old cupboard (8 mm) for the case, and some
new 4 mm plywood for the top cover, which is not as dark as the rest.
The first image shows the finished box without the electronics and you
can clearly see the black battery holder, fitted inside the case, and
two 3.5 mm stereo sockets for the serial ports. One socket is wired as
suggested elsewhere on this website and connects to
the PC.
The other 3.5 mm socket is used to connect an LCD terminal that is used
to display the decrypted text. As the LCD terminal only needs the TX line,
the other wire (normally used to carry the RX signal) is tied to +5V
to provide power for the LCD terminal.
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Using only 2 AA type batteries
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Rather than using a standard 9V block battery, which won't last very
long if the Enigma-E is used extensively, Peter has used 2 standard
AA size batteries, e.g. Alkaline, NiCd (chargable) or NiMH.
As the two batteries together will produce no more than 3V,
but the Enigma-E requires at least 5V to operate,
so Peter had to come up with a solution and designed a small
but cunning circuit.
The circuit is based on
the LT1073
Switching Regulator from Linear Technologies,
which can deliver up to 100 mA in this circuit, more than sufficient
for the Enigma-E.
The PCB with this circuit is fitted to the bottom of the case, as can
be seen in the leftmost picture above.
The black tube to the right of the small PCB is the battery holder
for two AA cells, which can be accessed from the rear of the case,
as can been seen in the rightmost picture.
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Older versions of the Enigma-E board
If you want to use this circuit with your Enigma-E, some components
have to be removed from the Enigma-E PCB. The following components
should be removed and will not be used elsewhere:
C8, C15-C17, C23, C24, BRIDG1, D33, FUSE1, IC6.
The mounting hole of the 78M05 (IC6) is now used to accomodate the power
switch, as can be seen in this picture.
➤ View the circuit diagram
➤ Datasheet of the LT1073 Switching Regulator
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Newer versions of the Enigma-E
Please note that on later versions of the Enigma-E PCB, some components,
and hence the numbering of the ICs, have been changed. In his description,
Peter is referring to the power regulator (7805) that is located in the top
left corner of the main board. On later boards it is called IC9 (78L05).
It has no mounting hole and looks just like a normal transistor.
The pin-out of this IC, when looking at the text, is OUT, GND, IN.
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Some words about the circuit: The inductor is not critical.
It should be in the range between 50 and 100 µH
(toroid or pod core with low resistance).
The diode D1 should be a schottky type, D2 in uncritical
(universal type). The two 100nF capacitors should be ceramic capacitors.
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Please note that the modifications described on this page are suggested
by Peter Meijer and not necessarily by the Enigma-E development team.
Any modifications made to the Enigma-E are entirely at your own risc.
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Using the morse sounder without an extra buzzer
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If you want to use your Enigma-E to produce morse code, the manual
suggests to add an extra buzzer, similar to the one supplied with
the kit.
Peter, however, has used the existing buzzer to generate the morse code.
This is done by using a universal NPN transistor
(Tr1 in his circuit diagram, e.g. a BC547)
which works as a Wired-OR with transistor T7 on the Enigma-E board.
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© Crypto Museum. Last changed: Monday, 11 April 2011 - 10:43 CET.
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