Replica of the AMT72 by Human Since 1982

Projects General Guidance
1

Hello to you all,

While surfing on Internet, I came across the masterpiece A MILLION TIMES AMT72 by HUMAN SINCE 1982 and was immediately seduced. Today, I'm trying to reproduce this masterpiece, and as I'm not very well versed in electronics, I'd like to know, with your help, if my editing is “electronically” correct.

OPERATING PRINCIPLE

1 master module with an ARDUINO MEGA 2560 (chosen because of the I2C internal pull-up resistors)
18 slave modules, each with an ARDUINO NANO, 2 AX1201728SG drivers, 8 DRV5032 hall effect sensors and 4 BKA30D-R5 biaxial motors. The master controls the slaves via I2C.

Here you have the block diagram

Blocks
Blocks1118×893 88.9 KB

and here the wiring diagram

SLAVE MODUL
SLAVE MODUL1675×1190 83.3 KB

MASTER MODUL
MASTER MODUL1190×845 65 KB

Thank you for your feedback.

2

Good but the number of slaves possible to use is not unlimited anyway.

That likely calls for additional pullups. Read datasheets and their data regarding the I2C lines..

4

Thank you Railroader for the feedback

Capture d'écran 2025-08-27 224605
Capture d'écran 2025-08-27 224605518×388 16.7 KB

5

This sounds weird to me.
The Mega 2560 chip does AFAIK not have internal I2C pull up.
A Mega board has therefore physical set of 10k resistors added.

Multiple processors to control a bunch of stepper motors is a common beginner's mistake.
One processor with port expanders (shift registers) is a better solution.
I have posted a project on this site controlling 48 stepper motors with a single Classic Nano.
The limit with that board was about 150 motors (at full speed).

Did you search for the prices of commercial units.
Be prepaired to sink the price of a small car in a project like that.
Leo..

6

Could you please send the link to the project
Thanks

7

It all began here (click).
@ba47 made a variation of it.
Also see the Sparkfun ClockClock project.
Leo..

8

Thank You!

Not providing any exact recommendation for Your project general knowledge of using a bus, like I2C, You aim for a maximum I2C project.

One important part is the lenght of the I2C bus cables. It’s designed for rather short cable lengths.

9

Note that A6 on a Nano is analogRead only and has no internal pull up.
The Rx pin of the ESP8266 could be damaged by the 5volt-logic of the Mega.
It should include a 1k:2k2 resistor level shifter.
Leo..

10

The artworks being imitated sell for USD 100K-200K.

11

BKA30D-R5 biaxial motors.

Are driven like the X27 automotive gauge steppers, and require a special pulse sequence for accurate positioning. What is your plan to produce that pulse sequence?

An 8 pin ATtiny would suffice as a driver for one X27 gauge motor but 8 pins are required for the four motor coils on the biaxial stepper.

12

A library is available for those 6-step sequence motors.

The writer didn't think of adding an option to drive shift registers.
If modified for that, then a 74HC595 could drive one of those dual-shaft motors.
A single Nano could drive a whole train of shift registers. No other parts needed.
OP's current plan adds too much complexity. Upscaling is not as easy as OP might think.
Leo..

13

The maker of the project in post#1 must have used different motors.
No way you can fit BKA30D-R5 so close together.

There are AFAIK dual-shaft X27.168 motors available for two pointers, at a price.
Leo..

14

Oddly enough, the diameter of the outer motor shaft of the BKA30D-R5 does not seem to be available to the public. Neither are in the data sheet, but according to an eBay seller, the inner shaft diameter is 1 mm.

15

The rotation angle of the inner shaft is also limited to 270 degrees,
which makes it a poor display for a clock.
Leo..

16

Oops! And the outer shaft is limited to 320 degrees. Useless for a standard dial clock.

Anyway, that motor was fun to think about, for a few minutes. :wink:

There is the Arduino Lunch Time Clock Project, which hacks a regular digital clockwork. Its purpose is to extend the time you have for lunch.

17

The X10.504 is an Analogue Car Clock motor.
No separate hour/minute drive though.

There are X27.xxx motors with two decks and separate inner/outer shaft drive.
Seems to be the X40.xxx family.
Leo..

18

https://www.aliexpress.com/item/32854428147.html
72 motors > US$615.75

19

Do you recommend buying this from aliexpress?
Or is this a minimum price indication?

20

Just a hint if you want to go for the smaller X40 motors.
Wise to order several types of motors before you commit.
And make a small prototype first.
Saves you from making costly mistakes.
Leo..

21

For a work of art (as well as time display like the AMT72) the single shaft motor would be fine, just a bit more limited in the number of interesting patterns that could be displayed by an assembly of them. Costs only about USD 2 on Alibaba.

A symmetric pointer with a centered mounting hub might be a better choice for that.