# Very simple electronic projects for beginner

#### Emoticn

Jun 4, 2017
1
hi all,

Beginner to any electronic projects and would be interested to start my first project.
I was to design a controller that can sensor the rotation angle of a wheel, and able to send out signal on a fixed multiplier basis of the rotation angle.
I decide to use Hall effect sensor and gear to generate input pulse. I can get fixed angle based on my gear design. Let's say the angle between each gear tooth is 7 degree. I would like to have a control unit onboard to send out signal to trigger my electromagnetic device with every 7, 14, 21, 28, etc degree of rotation of input wheel, and it's better to have a small LCD to show it. What electonic component will I need to design a board that fit my need? The input power is 12v by the way.

#### BobK

Jan 5, 2010
7,682
This is more complicated than you think. A Hall effect sensor will not, by itself, give you the rotation angle. It will tell you whenever a magnet passes over it. If the wheel goes in only one direction, and you know the initial angle, you can count pulses to determine the new angle. But what happens if the system loses power? When it starts up, again you don't know the initial angle unless it either automatically goes to some home position on startup or you have saved the position in non-volatile memory (memory that persists when the power is off). Things are even worse it the system might be moved, say by hand, while the power is off.

There are optical encoders that use use a bit pattern to give you the absolute position. This would be the most reliable way to determine the actual angle.

Showing the position on an LCD would require a microcontroller and programming.

In any case, this is not a simple beginner project.

Bob

#### Irv

Jun 7, 2017
112
I have done that with a $3 Arduino nano clone and a$6 display. You're simply counting pulses and displaying them on the readout. Code AKA 'scripts' for this are all over the web, and are relatively simple.

HOWEVER, as BobK wrote, the real problem is two fold: first, is getting reliable (never skip regardless of speed) input detection from the hall sensor, and second, the homing problem. Counting pulses isn't going to mean much unless you know where you started.

For demonstrations, you could just add a switch to manually reset to zero when you have the input wheel at zero. For any actual use, you would need to account for all the possible failure modes he mentioned.

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