Picture of Make your own Enigma Replica

EDIT: This Instructable has won Second prize in the 2013 Radio Shack Microcontroller Contest. Thank You to all who voted!

EDIT2: Our "Open Enigma Project" Kickstarter https://www.kickstarter.com/projects/438986934/the-open-enigma-project?ref=search is now over. Please visit www.stgeotronics.com if interested. THANK YOU for your support!

This is our very first Instructable and this step by step guide will show you how to build a fully functional electronic replica of the world famous German Enigma machine. This Arduino based Open Source project is able to encrypt & decrypt any Enigma M4 encoded message.

This first ever fully functional Open Source Enigma "exact " Replica was inspired by the Kid's Game to Arduino Enigma Machine by sketchsk3tch.

Using Charlie-plexing Multiplexing for the LEDs, this circuit with 115 light emitting diodes uses only 38 pins and the 36 push buttons use only 4 pins total thanks to properly placed resistors (and the P-Channel MOSFETs) in the keyboard loop. These 4 16-Segment displays & an LED for each keyboard button would add up quickly the total number of pins required and even the Arduino Mega would have ran out of pins without the 2 methods mentioned above....

In response to the overwhelming demand, we designed the PCB and made it available through www.stgeotronics.com. Skip to Step 10 & beyond for more info. We also offer it as a complete electronics kit & an assembled & tested complete product.

Step 1: Proof of concept on Breadboard

Picture of Proof of concept on Breadboard
Before going all out on the development of this electronic Enigma replica, we wanted to make sure we could properly drive the 16 Segment LEDs. If we can do that, than we will be able to do everything as the rest is only Math...
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ST-Geotronics (author) 1 year ago
Boards are tested, working great and available now for shipping. Kits & assembled/tested/boxed Enigma Replicas are also available. www.stgeotronics.com to order.
DIY93931 year ago
This is amazing!

You deserve a reward!
If you don't mind me asking, how much did all of this cost you?
ST-Geotronics (author)  DIY93931 year ago
Thank You DIY9393 for the kind words.
I guess we should have mentioned the hardware costs in the instructable. All in all, we spent less than $200 in materials. But QUITE a few hours...
No problem!

Thanks for the info!
ST-Geotronics (author) 1 year ago
The PCB drawing phase is completed. We have ordered them from the Fab & are anxiously awaiting their arrival so we can populate & test 1 set ensuring that everything works fine. As soon as this crucial step is completed, they will be available for ordering/shipping.

NOTE: There was NOT enough space on the Enigma PCB to have all necessary components AND connect to the Arduino Mega2560, so we had to create a daughter card for the Mosfets & to receive the Duino. This daughter card will be sandwiched between the motherboard & the Mega2560.
ST-Geotronics (author) 1 year ago
We just posted the second and last Circuit Schematic (for the lampfield and keyboard) at the end of the instructable.

We will start soon working on the PCB design, so stay tuned. Don't forget to vote, every vote counts. Thank You!
Thank you!!
reflector wheel=b
wheel order 1,2,3ring setting A,A,A
ground setting RAF
ST-Geotronics (author) 1 year ago
In response to the popular demand, we just added the first of 2 Circuit Schematic at the end of the Instructable. You can now find how each of the 4 16-Segment Displays are wired. Stay tuned: We are currently working on the 2nd Circuit Schematic, which will show the rest of the Perfboard wiring: how the 26 keyboard buttons, the 10 function keys, the 26 keyboard lamps & the 5 LEDs are all hooked up. After that, we will design & post the PCB file.

Thank You for the overwhelming positive feedback & don't forget to vote for this Instructable in both contests if you enjoyed it.

thompsms1 year ago
I just can't wait for the PCB!! Astounding. You deserve a Bletchley Park Medal.
Junophor1 year ago
I am really deeply impressed!!
Take a bow

Yours Aeon Junophor
bob30301 year ago
Most intriguing instructable I've seen. Must be a record for lines of code in an instructable. Your patience in the wiring is commendable. I would be interested in the PCB you mentioned. Thanks for posting.
DiegoC149 days ago
DiegoC149 days ago
kousheekc2 months ago


kousheekc2 months ago


DyerMors8 months ago

I was wondering about the plugboard. If i haven't got that wrong, it isn't really connected, it's only for imitation proupose, isn't it? All the plugboard thing is handed by the programm?

ST-Geotronics (author)  DyerMors8 months ago

Originally, and as described in this Instructable, you are correct, the plugboard was only for show as it was implemented in software only. However, we have since modified the daughter PCB to receive a fully functional plugboard. This 3 PCB combo is now available as circuits boards only, kit, and fully assembled unit at www.stgeotronics.com

Step 18 Daughter Ribbon.jpgStep 19 Plugboard Ribbon.jpg

Schematics for the plugboard would be excellent. Any plans to release?

I was wondering, though, will you ever give us the schematics for the project with the fully functional plugboard?? I'm relatively new to electronics so figure out a solution to implement the plugboard is quite a difficult task :(

That's really amazing, but just for the sake of the challenge, i wanna build it on perfboard, but i still love the fact that you make available the pcb as well as the project schematics! Keep up the awsome work

SimonAdam7 months ago

Wow, this is amazing and an epic code... good work.

I was wondering if you able to provide a schematics for the project with a fully functional plugboard. i would like to know how the plug board is wired and how it fits into the Arduino or daughter board?


do'malley7 months ago
I am currently building this, but can you tell me which switch on the board is switch 0, switch 1 etc. Is it like the attached image with mode button as sw0? I dont want to wire it up wrong. Excuse the crude editing, it was done using android!

Thanks, David
DavidO29 months ago

What exactly are the "Alpha buttons" and where can I find them?

Are LEDs attached to them to light up the correct letter, or how does it work?

ST-Geotronics (author)  DavidO29 months ago
DavidO2, for the first unit we ever made described in this instructable, (and the next couple), we used normally open buttons containing a blue led with a cap with a character of the alphabet. We found these on ebay but seem to no longer be available. These were a pain to install and solder, not to mention very expensive.

Since then (and for every machine sold in our kickstarter), we simply used surface mount white LEDs and added a printed sheet on top that contains every key in sequence of the keyboard. This provides more light and looks a lot more like a real Enigma...

Visit www.stgeotronics.com for components, kits and assembled/tested units...
Razapple121 year ago

What kind of buttons did you use? I'm trying to make one... :) This is a really great looking replica by the way

ST-Geotronics (author)  Razapple121 year ago
Razapple12, Like most everything else, we found them on eBay:

Search for something like: "Momentary Tactile Push Button Switch 12x12x11mm DIP + Black Round Cap"

This is an example:


Razapple121 year ago
Where did you buy your buttons?
ST-Geotronics (author)  Razapple121 year ago

Razapple12, Like most everything else, we found them on eBay:

Search for something like: "Momentary Tact Tactile Push Button Switch 12x12x11mm DIP + Black Round Cap"

This is an example:


nwsayer1 year ago

This is great, but it always astonishes me greatly when folks embed a prototyping board in a custom printed circuit board design. If you're going to all the trouble to design a custom printed circuit board, then why not just embed the ATMega chip directly into your design? It just can't help but be cheaper, lighter and smaller that way.

MarkCauer1 year ago

How does the arduino measure the resistance if there is no current traveling through the resistor and pushbutton setup? Shouldn't there be a ground somewhere?

qbrown21 year ago
I guess i can peak at the code but how did you translate the 7 segment digit dispays to nixie ?
ST-Geotronics (author)  qbrown21 year ago
QBrown2, we didn't:

The 7 Segment displays are actually 16-Segment displays (17 if you count the decimal point) and we are using these as opposed to 7 Segment so we can have a nice Alphabet.

We decided to wire them standing up & encapsulate them inside a test tube to give it somewhat the look of period accurate Nixie Tubes.

So, no Nixies were used in this project...
P.S. the printed circuit board we made allows for 16-Segments LEDs to be horizontal or vertical, but still has not been designed with Nixies in mind...
ST-Geotronics (author) 1 year ago
Thanksgiving Holiday brought us our Prototype boards. We are now busy populating & testing one to make sure it works as great as the proof of concept does. We are now accepting orders at www.stgeotronics.com & expect very soon to start shipping. We added Step 10 to this Instructable to show pictures & more details.

ST-Geotronics (author) 1 year ago
We are finished drawing the motherboard PCB (top), and have started drawing the daughter car (interface between top PCB & Arduino). Daughter card is required cause we can't fit all components on motherboard. As soon as daughter board is complete and we verify they fit together in Enigma machine, we will send them for production. We expect both boards in our hands sometime in December.
Thank you. Will you upload the PCB design file?
ST-Geotronics (author)  englishfire1 year ago
Yes englishfire, we will upload both PCB design files (Motherboard & Daughter Card) once they are both complete & tested. We are aiming for sometime in December.
Any news about the PCB?
ST-Geotronics (author) 1 year ago
stringstretcher: Reflector wheel= C Wheel order = 3,2,1 ring setting A,A,A Ground setting = USA IYRF TTQP DUPA AIMC DBTG YTNF

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