Category Archives: News

Glowing marquee

Inspired by the Record Player Display projet, I start doing one of my own. A glowing stripe marquee, using an old scanner ripped off. The objective is to learn how stepper motors works, optic switch and resume my experience with logic chips like the 74HC595 shift register. Globally, everything is relatively simple and it’s just a matter of seeking the right information over the internet, and a bit of thinking. The current video is presenting my first test, without the mechanical part. Just the leds and the glowing vinyl stripe moved manually. The last week, I solder the leds and the shift register on an permanent circuit board. It will be fixed on the scanner soon. The optic limit switch works and it will be used to know the reset position of the scanner. The next step will be to assemble the circuit board for the step motor driver. I use a L293D. So happy viewing. You will understand why I certainly make some mistake in my writing.

Step one, step two, motor on!

When I was young, I had two unipolar (don’t know that detail since this week) stepper motors. My pleasure was to connect them together and when I spinned one, the other performed nearly the same rotation. It was a great pleasure to play with. But I finally make one (bipolar) really work today. Yeah! I work hard to understand the motor I got, the MITSUMI M42SP-4. When I look over the Net to find some specs, it’s never what my motor look like. So I guest a four wires bipolar, and I tried it on 5v, safely. Something append, but not correctly. Any bad connections with the L293D? I think not. I found, after a while, that my problem was the Arduino stepper library. I don’t know if I was doing something wrong but it’s look like the stepper function always stimulate both coils at the same time. So I coded an ugly function to recreate the four steps needed, and Bingo! This will make my projet go further.