Hardware help Please

I would like to order all of the parts necessary to build a 1 year clock... (servo motor, controller, battery pack, usb cables, and whatever else I would need) Sorry, I shouldn't guess at the model numbers. I'm New and I want to start off on the right foot...

So, I would need the servo to rotate 1/365th of a revolution (or rotate backwards a bit first then forward to the desired position), once a day. The result being 1 full revolution in 1 year... mounted to the wall-as a clock would be. The position needs to be "close", not infinitely perfect.

-Additionally there will be a "single clock hand" that will be of balanced weight, it will weigh 6- 8 ounces. creating a slight side load on the servo motor...

I will order them today if you have a complete list of bits that I would need. Also if what im requesting cant be bought and I would require a third party motor, would you be kind enough to let me know which one...?

You probably want a stepper motor, one that you give a pulse of energy to step from position to position,
I am not aware any that have that few degrees between steps. The best I can recall seeing are 1.8 degrees per step, or 200 steps/rotation.
What you may have to do is use that and some gearing so that each step is 1.0139 degrees.
The rest - a promini, an FTDI Basic for programming it, a DS3231 RTC, a huge battery pack, a stepper motor driver, are pretty standard.

A normal servo is an "angular" motor that only turns about 270 degrees.

The nice thing about a stepper motor for an application like this is that it has "mechanical memory"... That is, even with power removed it will tend to hold it's last position. Just step it once a day. A servo would (probably) have to be continuously powered.

With a stepper motor, you will probably need "home position" sensor, although with an application like this, you could set the starting position manually. Unlike a servo, a stepper doesn't "know" it's absolute position. It only knows how many steps it's made from the starting position. (Well, the motor doesn't know anything, but your program does...)

And, you can gear it down to more than 1 step per day. (Timing pulleys are probably better than actual gears.) Since 200-step stepper motors are common, and 1 degree is a common angle, I'd guess you can find timing pulleys with a ratios that divide evenly.

adam_bgi:
I would like to order all of the parts necessary to build a 1 year clock... (servo motor, controller, battery pack, usb cables, and whatever else I would need) Sorry, I shouldn't guess at the model numbers. I'm New and I want to start off on the right foot...

If you are new I suggest NOT buying all the stuff before you start because as you learn you will have more knowledge from which to decide what you need.

Also you should be aware that a complex program is just a collection of small pieces and you should develop/learn each piece separately before trying to "join" them together.

If you are going to use a stepper more please read stepper motor basics before you spend any money. Also note that that Thread does not deal with the small 28byj unipolar stepper motors which may be sufficient for your clock.

..R

The Greatest Common Factor of 365 (days) and 200 (steps per revolution) is 5 so the ratio is 73 to 40. Put a 40-tooth gear on the stepper and a 73-tooth gear on the pointer shaft and you will get 365 steps per revolution.

Awesome input guys!!! I Appreciate the tips as yes, I am a newbie… The specifics that you have provided are a great starting point for me.

This is a hobby project for me as well as a learning project, it’s my intent to learn the programing language also. If you have any recommended links, or books that step a beginner thru the programming language, I would appreciate that also.

  • I’m new to this forum and must credit it, this is the best forum that I have posted a question on. THANKS! Great answers!

Adam