Overlapping Segments Rotary Digital Clock

Darrell Aldrich's smart idea of overlapping segments digital clock,

https://www.youtube.com/watch?v=Ol5JYbCdf2A

is used to make the digits relatively larger than former Rotary Digital Clock.

Instead of painting segments, printed part is just sticked to the rotor.

Necessary parts

• ESP32 based micro computer
• 28BYJ-48 geared stepper motor and driver circuit comes with
• Several 2x8mm tapping screws
• Wire, soldering iron, lubricants such as silicone oil
• Double sided adhesive tapes or superglue

• Print all parts with supplied posture.
• body.stl needs support for print.

• Remove blobs and debris well. Especially, the both sides of rotors should be smooth.
• Stick or glue the segments to the rotors.
• Attach circuits and the motor into the axis with 2x8mm tapping screws.
• Stack all wheels. Place spacers among wheels.

Using Arduino IDE, flash program to the clock. Please start from the demo.ino that shows numbers from 0000 sequentially.

You can set SSID and password of your WiFi using smartphone app.

This function is named SmartConfig. The apps for setting are at

Android : https://play.google.com/store/apps/details?id=com.khoazero123.iot_esptouch_demo&hl=ja&gl=US

iOS : https://apps.apple.com/jp/app/espressif-esptouch/id1071176700

The way to set SSID and password using apps are shown in the video of former rotary clock.

The status of WiFi connection is indicated by the motion of the rotor.

• Large reciprocal motion : connecting to WiFi of past setting stored in non-volatile memory.
• Small reciprocal motion : SmartConfig mode. If 30 seconds of WiFi connection trial fails, it automatically moves to the the smartConfig mode (waiting for the setting from smartphone app.)

Please note that your smartphone should be connected to 2.4GHz WiFi.

Q1. A rotor is unintentionally rotated by the neighboring rotor.

A1. The position of the stepper motor is also very important. If the motor is not centered precisely, the second wheel is unintentionally rotated. It is also useful to increase the thickness of spacer if you are making the numeric type clock.

Q2. Can I use Wemos D1 mini or ESP8266 based board?

A2. I have not tried them yet because Wemos D1 mini and most ESP8266 based board can not be used in Japan legally.

Q3. I would like to set WiFi settings in the source code directly.

A3. Please take a look at the top of the source code. Turn off the flag named WIFI_SMARTCONFIG (at line 10), from true to false. In this case, you should write your SSID and password.

Q4. How to change the source code between 12H and 24H versions?

A4. Please take a look at the top of the source code "7seg.ino". Turn the flag named HOUR12.

Q5. It seems that the motor is rotating to the opposite direction.

A5. Please take a look at the source code Change the content of array named port[4] .

Q6. Numbers or segments are not well aligned.

A6. Some parameters to tune the alignment are prepared in the source code. One is the KILL_BACKLASH parameter which compensate the backlash of internal gear of the stepper motor. The other parameter is in the function setup(). When the motor pushes the rotor to the endstop, it will be distorted. The value at the comment "release pushing force to align all digits better" could be tuned to compensate it.

Q7. Sticked segment peels off.

A7. Some options to solve this problem.

• Wrap the rotor with transparent adhesive tape, as shown in the picture above
• Stick the segment part to some cylindrical object (radius is around 7cm) using adhesive tape. Then warm up it using hair drier or heating gun. After cooling down, it is nicely curled and easy to stick without peeling off.

This clock is based on Darrell Aldrich's smart idea of overlapping segments digital clock shown above.

My related projects

• Minimal Mechanical Digital Clock with Network Time Acquisition : 1st version of numeric type clock
• Rotary 7-segment clock : 1st version of 7-segment type clock. Detailed description on how to show 7-segment number with only 3 rotors are there
• Rotary Digital Clock : 2nd version of two projects above. It has mechanical endstop to initialize, so photosensor is not necessary.