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• The control electronics

  Elbert • 05/22/2024 at 20:07 • 0 comments

  The control of the digitizer consists of a PC (laptop) running (through Virtualbox) Linux mint. A C++ program (control) reads the serial port of the ESP32 and captures the frame by invoking the fswebcam program to get a picture from the microscope.

  The ESP32 runs a program (stepper) which gets commands through the serial ports to run the stepper motors and sends back a notification when the stepper motor has reached its target position.

  A variable PWM module (powered from the ESP32) controls the strength of the LED.

• The first prototype

  Elbert • 05/20/2024 at 20:26 • 0 comments

  For a first try, I take the configuration of the manual viewer as layout. I need two stepper motors. The first one is connected to the wheel with tooth that grab into the holes in the film. It has 12 tooth, so 1/12 turn of this wheel advances one frame. The second stepper motor (although it could have been a normal motor) turns the spool. It should be able to slip, so I made a few different clutches.

  I used the simple 28BYJ-48 geared stepper motors with ULN2003 drivers.  

  I made a frame and holders for the stepper motors in OpenScad and sliced it with Cura.

  The best clutch was an outer ring with spring-like pins, and an inside wheel with an curved surface.

  Problems with this first prototype: 

  • The film was too loose around the wheel, so it slipped. 
  • The microscope holder was off. 
  • And it was too dense to tweak. 

  So the second prototype has to be wider, several options for the guarding wheels to get enough tension, and a proper place for the microscope.  

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