nategri / chernobyl_dice, Hacker News

In this clip the Chernobyl Dice set to continuously generate numbers in the range [1,26]. You can check out a longer YouTube clip showing various modes of here:https://youtu.be/8uue9Aae9ss

************Introduction

************************** Description

The Chernobyl Dice is a quantum random number generator [0] that uses nuclear decays from a weakly radioactive sample as a source of entropy. It consists of four primary components:

An Arduino Nano microcontroller
A Geiger counter
Nixie tube display

Geiger counter events (“clicks”) are converted into random bits using the following algorithm:

In a ring buffer, for each millisecond record either a 0 or a 1, depending on whether or not a Geiger event occurred Perform an initial de-bias of this 0-dominated stream using von Neumann’s method [0]
1. Further de-bias by XOR-ing bits generated in the previous step with the mod2 of elapsed 4 microsecond intervals since since the device was powered on

   The uranium glass sample is illuminated by an. array of ultraviolet LEDs at each Geiger event, which makes them fluoresce bright green. This has nothing to do with the radioactivity of the sample, but it does, however,

   look really cool (**********************************.) ********************************

   Operation

   The device has three modes of operations, which can be selected via the rotary switch:

   Clock Mode

   Displays the current time, with the Geiger board unpowered. The time can be set by flipping the toggle switches on and off (the ‘‘toggle increments the hour, the’ 8 ‘toggle increments minutes, the ‘4’ toggle increments 1 minute, and the ‘1’ toggle resets the seconds).

   Streaming Mode

   Repeatedly generates random numbers of a size specified by the toggles (or random bytes from 0 -********************************************************************************************************************************** if no toggles are set. Numbers generated in this mode are transmitted over serial via USB. This mode also has a “turbo” setting to facilitate statistical testing, which can be enabled by holding down the pushbutton. When “turbo” is enabled bit generation will be indicated by LEDs in the display, and the Geiger “clicks” will be silent.

   Dice Mode

   In dice mode random number generation is initiated via the pushbutton, and the size of the random number to be generated is set by the sum of the toggled switches (no switches are set the device will generate random byte in the range 0 – 500. Press once to generate the number, and once again to clear the display. The size of the number to be generated is displayed in blinking digits.

   ******************* Statistical Performance

   Further testing is required to confirm the consistency of results, but currently the Chernobyl Dice is capable of generating a 1.5 megabit file that passesa Python implementationof the NIST statistical test suite [1]. This means the Chernolbyl Dice is likely a

   very fair dice. SUMMARY ——- monobit_test 0. PASS frequency_within_block_test 0. PASS runs_test 0. PASS longest_run_ones_in_a_block_test 0.PASS binary_matrix_rank_test 0. 0753308212732 PASS dft_test 0. FAIL non_overlapping_template_matching_test 0.PASS overlapping_template_matching_test 0. PASS maurers_universal_test 0. PASS linear_complexity_test 0. 938296605093 PASS serial_test 0. 629208901365 PASS approximate_entropy_test 0. PASS cumulative_sums_test 0. PASS random_excursion_test 0. 999998184707 PASS random_excursion_variant_test 0. PASSSUMMARY ------- monobit_test 0. PASS frequency_within_block_test 0. 672504584189 PASS runs_test 0. PASS longest_run_ones_in_a_block_test 0. PASS binary_matrix_rank_test 0. PASS dft_test 0. PASS non_overlapping_template_matching_test 1. PASS overlapping_template_matching_test 0. 0753308212732 PASS maurers_universal_test 0.PASS linear_complexity_test 0. PASS serial_test 0. PASS approximate_entropy_test 0. PASS cumulative_sums_test 0. PASS random_excursion_test 0. PASS random_excursion_variant_test 0. 424389760139 PASS

   Statistical test suite results for two byte random binary sequences ('rand.binary.1' and 'rand.binary.2') generated by device. EXPERTS NOTE: The last two tests of the first sequence generate the message: 'J too small (J=

   The directory (statistical_testing) ************************** contains some utilities for assessing and gathering data from the device, including sample random binary data files,rand.binary.1 and (rand.binary.2) **************************************. **********

   CAD Drawing

   A Fusion 728 CAD drawing of the device can be viewed and downloaded at this URL:

   https: // a 300 .co / 2OeFT1n

   **********

   Thanks to the following GrabCAD users for their models:

   Alex(Nixie tube)

   (Arduino Nano) (****************************(Various pin headers) (************************************************************************** ********************** and Parts List

WARNING: These instructions and resources are not polished and are somewhat untested. This is a project for advanced makers, and you should fully expect to have a bit of an adventure while building your own Chernobyl Dice! That said: Shoot me a message if you run into trouble, and I’ll try to help you out and improve the instructions as well.

**********

Print or fabricate the following custom parts from files in the GitHub repository

Enclosure (using 3D printer or 3D printing service)
Logic, Nixie Display, and Control Panel Custom PCBs (using a board fabrication service such as OSHPark) Stainless steel front panel (using a service such as OSHCut)
Acrylic back panel (using a service such as Sculpeo) (******************************

Order other components (see URLs in the parts list)

Embed brass standoffs into enclosure (this is how front and back panels and custom PCBs will be mounted)

TIPS
A single drop of cyanocrylate (superglue) should be placed in the standoff holes in the enclosure before they are pressed in (the tip of a Phillips head screw driver works well for this task)
If the tops some holes came out of the printer a bit distorted then they can be widened easily by twisting a largish Phillips head screwdriver in them until the top of the hole is wide enough.

Assemble custom PCBs and ‘exixe’ nixie tube driver boards using build photos as a guide

TIPS
The female headers on the Nixie Display Board for the nixie tube driver PCBs can be assembled using only four long female header strips (eg there’s no need to separately attach sixteen 7-pin female headers — see photos)
The “CS” 8-pin male header is a currently a tight fit, so you will probably need to use needle noise pliers to push the pins through the board
For the control panel PCB you can temporarily mount the toggle switches in the front panel and then press the PCB on top of the back of the switches to ensure good alignment — you can then pull the whole board-and-toggle assembly off of the front panel to solder it, or even solder it in place and then pull it off
The file ‘nixie_holder.stl’ is a provided as a useful place to rest the nixie tube while soldering them to the ‘exixe’ driver boards

Attach the acrylic back panel and panel mount USB cable to the rear of the enclosure

Mount custom PCBs inside enclosure and perform wiring (see wiring schematic and build photos)

Partially dis-assemble rotary switch to attach it to the “lock plate” (lock_plate.stl)

Perform any necessary finishing to the stainless steel front panel

TIPS
Some mounting holes for toggles and switches may need to be widened (use a round file for this)
Surface finish of a laser cut part can be improved by sanding (with the grain) ******************************** (using ~) **************************************************************************************************************************************************** (grit sandpaper) test on the back side first)

Mount toggle-and-PCB assembly, LED-with-holder assemblies, rotary-switch-and-lock-plate assembly, and pushbutton on front panel

TIP
While attaching the LED to the holder, apply a drop of cyanocrylate (superglue) to prevent the LED from falling out of the front of the holder

Perform wiring of the control panel (see wiring schematic and build photos)

Fit the eight nixie display driver boards into the female headers of the Nixie Display Board

Wire the Control Panel to the Logic Board

Mount the front panel to the enclosure, taking care to insure that the hole in the rotary switch lock plate lines up with the upper-left standoff on the front of the radioactive sample holder

**************************************** (Standoff Size Guide) *************************************************

(**************************************************** (Location) **************************************************** (Standoff Length) (Type) (******************************************************** (****************************************************** (Rear of enclosure)

(mm) (Female-Female) ********************************************************** (****************************************** Front of enclosure (mm) (Female-Female) ********************************************************** (****************************************** Nixie Display Board mount************************************** (mm) ********************************************************** (Female-Female) ********************************************************** (****************************************** Logic Board mount************************************** (mm) (Female-Female) ********************************************************** (****************************************** (Logic Board-to-Geiger Board) (mm) ********************************************************** (Male-Female) ********************************************************** (****************************************** (Geiger Board-to-Bottom of Uranium Sample Box) ********************************************************** (mm) (Male-Female) **********************************************************Bottom of Uranium Sample Box-to-Top of Uranium Sample Box (********************************************************** (6 mm) ********************************************************** (Male-Female) ********************************************************** (****************************************** (Top of Uranium Sample Box-to-Front Panel) ********************************************************** (6 mm) ********************************************************** (Male-Female) ********************************************************** (**********************************************************

NOTE: For large internal standoff distances (eg the Nixie Display mount) two standoffs can be stacked to achieve the desired distance.

****************************************

How connect the internal wiring of the Chernobyl Dice.

********************** Build Photos

Enclosure with Standoffs Inserted

(******************************************************************

**********

You can ignore the white breadboards on the left of the enclosure. These assisted in an earlier iteration of the project and are not needed for assembly.Click herefor larger photo.

(Logic Board Mounted) ************************************************

**********

Note the wires for UV LED array are run beneath the logic board. Click herefor larger photo.

(Nixie Display Board Wiring) ************************************************

**********

Click herefor larger photo.

(Nixie Display Board Mounted and Logic Board Wiring) ********************************************

(**************************************************************************

Click herefor larger photo.

(Geiger Board Mounted) ************************************************

(******************************************************************************

NOTE: You must pull the JMP2 jumper near the center of the Geiger board (this turns off the built-in speaker of the board — we want these clicks to be optional and controlled by firmware instead). Click herefor larger photo.

Uranium Sample Holder Lower Half Detail

(**********************************************************************************

UV LEDs and piezo speaker are glued mounted into place using cyanocrylate (superglue) adhesive. Uranium glass marbles will be held in place mechanically when the top half is mounted. (Click herefor larger photo.

Uranium Sample Holder Lower Half Mounted

(**************************************************************************************

The middle standoff is attached on the underside with a nut. (Click herefor larger photo.

Uranium Sample Holder Top Half Mounted

() ****************************************************************************************

(Click herefor larger photo.

(Control Panel Board Wired) *************************************************



(Click herefor larger photo.

(Control Panel Board Wiring Detail) **********************************************

**********

Click herefor larger photo.

Many thanks to Emily Velasco (@ MLE_Online

for advice on stainless steel surface sanding, and for generally being enthusiastic as heck about this project.

[0] “Quantum Random Number Generators.” M. Herrero-Collantes and J. C. Garcia-Escartin.https://arxiv.org/abs/ 2019. 212667

[1] “A Statistical Test Suite for Random and Pseudorandom Number Generators for Cryptographic Applications.”https://csrc.nist.gov/publications/detail/sp/ – / rev-1a / final

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