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Improve your Enigma-E with these suggestions
We've just finished the wooden boxes for our own Enigma-E units
and have made some nice enhancements that we'd like to share with you.
First of all, we've added some chargeable batteries to the unit, plus
a proper charge circuit. Next we found a place to put the power socket,
the power switch and the socket for the serial port. One of the most
significant improvements we've made so far is the addition of white
LEDs on the lamp panel though...
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Contents of this page
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Using chargeable batteries
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If you want to carry your Enigma-E kit around and use it in every
location, you might want to add chargeable batteries to it. You can
use standard AA-size NiCd batteries, which are relatively cheap these
days. 6 of such AA-size cells will give you about 7.2V (1.2V each),
which is enough to power your Enigma-E for days.
When using chargeable batteries, it's important to use a proper
charge circuit. Just applying a voltage isn't suitable and is likely
to damage your battery cells. A proper charge circuit is given in
the drawing below. It supplies a constant current of 60mA to the
batteries, which is 10% of the maximum current the battery can deliver
without damaging the cell.
This curcuit required only a few components and can easily be built
on a small piece of vero board. You may even be able to fit the
batteries and the charge circuit in a small case which can be mounted
inside the Enigma-E box.
For this circuit, we've made use of the rectifier that is present on
the Enigma-E PCB (BRIDG1). The power from your adapter first goes
to the rectifier on the Enigma-E board (AC1 and AC2).
The output from the rectifier (N)
goes to the charge circuit. The output of the charge circuit goes
to the Enigma-E circuitry (C). The circuit is in effect a constant current
source, the base of which is formed by the transistor TR1 and the
yellow LED D1. Please note that we've used an LED to create the
correct reference voltage. The Zener diode D2 is used
as a protection against overcharging.
F1 can be an ordinary fuse, but it's better
to use a self-restoring multifuse instead.
Please note that it is important to use a 100mA fuse as close
to the battery cells as possible, despite the
fact that the Enigma-E PCB already contains a fuse. After all, you
are using wires to connect to the switch and the PCB and if you make
a mistake you will need the fuse as a protection.
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Fitting the socket for the power adapter
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The kit is supplied with a socket to allow you to connect an external
power adapter. Many people have asked us what the best place would be
to fit the socket. Of course, if you've built a wooden box around the
unit, you could drill a hole in it and fit the socket. That would
however destroy the authenticity of the case, now wouldn't it?
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After a bit of trying and probing, we found that the ideal place to
put the power socket, is on the Steckerbrett. Both at the left and
at the right of the Steckerboard sockets there is enough room to fit
a socket.
We've mounted it on the right hand side of the Steckerbrett as you
can see in this picture. Be careful when drilling a hole in the
Steckerbrett PCB as you might otherwise damage the tracks on the
rear side. If you do, don't worry, you can easily repair them with
a couple of wires.
As we wanted to be able to see that our unit was on, we've added
a bright blue LED to this panel as well. Fir this, we've drilled
very small hole in the YiG logo, as you can see in the picture.
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Below are two images showing the rear of the Steckerbrett PCB.
You can clearly see how the power socket and the blue LED
have been mounted.
Please note the series resistor (used between the power source and the LED)
and a protection diode (1N4148) connected anti-parallel over the LED.
The latter is used to protect the LED against reverse current in case you
are using an AC power adapter.
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Whilst on the subject of modifying the Enigma-E, we found a good
place to mount a power switch. For this we've used the centre hole
of the Steckerbrett. This hole is intended as a mounting hole when
using the PCB in a horizontal position. However, in the wooden case,
the Steckerbrett is mounted straight up and the centre hole isn't used.
Find a suitable tumble switch and solder or glue it to the rear of the PCB.
In the images on the right you'll see a tumble switch glued to the rear
of the Steckerbrett, using two-component glue. The hole had to be enlarged
slightly.
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Fitting the socket for the serial port
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The Enigma-E has a fully functional serial port that can be used
to connect the machine to, say, a PC (using a terminal program)
or another Enigma-E. Normally, a 9-way sub-D connector is used
for this purpose, but that may be too large to fit to the Enigma-E.
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One user suggested to use a 3.5 mm stereo mini jack for this
purpose, which fits nicely on the left hand side of the Steckerbrett.
As you can see in the picture, we've tried this too and we're very
happy with it.
Before drilling the hole somewhere in the Steckerbrett, please ensure
that you are not cutting any tracks of the PCB. The area indicated in
the picture, is free from tracks in all versions of the PCB.
Also check the quality of the jack socket before buying one.
There are many variants of this socket, but the best results are
obtained with the slightly more expensive ones.
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The best way of wiring the 3.5 mm stereo jack is shown in the drawing below.
If we all use the same wiring, all Enigma-E machines can be connected together.
Use three-way cable to connect the serial port: 2 wires plus a shield.
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One wire is used for transmission (TX) and one for reception (RX).
The shield is connected to the Ground connection if the Enigma-E.
We've used the tip for TX, the ring for RX
and the ground for the cable shield. You may then use a cross
cable to connect two Enigma-E machines together.
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Using white LEDs on the lamp panel
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Although white LEDs are much more expensive than the usual yellow, green
or red one, we couldn't resist to try them out on the Enigma-E kit.
After an extensive search, we've found some low-power, high-brightness
ones which work well on the Enigma-E. Follow the link below to read
more about the use of white LEDs. Partnumber and datasheet are available.
Update: All Enigma-E kits with a serial number of 503 or higher are now
supplied with high-brightness yellow LEDs, so for these users there is
no need to swap the current LEDs for white ones.
➤ Read more about using white LEDs
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© Crypto Museum. Last changed: Tuesday, 05 August 2025 - 10:38 CET.
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