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A project log for Jumbled Clock

Jumbled digits on clockface, but hands still point to the correct digits

Michael MöllerMichael Möller 12/28/2019 at 18:360 Comments

The program has been written and the logic for when to nudge the hour hand has been debugged with plenty of Serial.print(). It is missing the clock stuff, as I still need to find a clockchip in my stuff or buy one.

A simple circuit with a ULN2001 to drive a simple 4 coil stepper has been created, and yes, the motor moves as it is supposed to.

Didn't need the the "Stepper" library, I just drive the 4 pins. With only full steps, the program logic is trivial. Turned off when stationary.

Having some difficulty with the stepper choice, both mechanical and electrical. I have a good stepper but it is large and heavy, but it runs at 5V with 200 steps/revolution. I have a smaller stepper which is better, but has only 50 steps/revolution, which is too coarse. OK, so a simple large gear on the hands being driven by the stepper would do it. I only need 4:1 or better. The lighter stepper wants 24V - but that is for full power, I can drive it at anything 10V-24V, the torque is still more than enough to move the hands. Which means two power rails (5V and something >10V), either two walwarts or a stepdown converter

Whilst I use a normal Arduino for development work, I want it on a dedicated board at the end.

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I'll go with the heavy 5V motor, to get a "beta"-version constructed. Pro: No gears, simple 5V supply, Con: heavy/bulky behind clockface.

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