Help with a project please?

[3rdgen8284]

Hi people,

I'm a newbie here and quite a green one at that so please be gentle! I'm trying to build a project and the thought process behind it is quite simple. I'll try to itemise it as well as I can.

I need a system which will rotate a sign 360 degrees, stopping at each 120 degree increment. In order to make it go to the next 120 degree position a button must be pressed. Thats it!! I'm guessing I'm going to be into a stepper motor but I don't know anything about PICs or programming them so I really do need your help and advice.

Really looking forward to the replies.

Oh for reference this is what I need..ish..., but with only one button and one direction of travel.

https://www.youtube.com/watch?v=WQKsll_ ... g&index=50

Thank you everyone!

[piratepaul]

What size and weight is the sign?
The size of the motor and spec of the transistors switching it depend on the torque necessary to move the weight and resistance of the sign.
You could make a counter from TTLs which switches the transistors and makes it work.
A microcontroller board and motor are likely to be available off the shelf but it might not be easy to make it do exactly what you want, you would need a multiple of 6 pole motor.

Tar&stuff.

[3rdgen8284]

The sign is 11x6", like I said I'm a total beginner but judging by the video it's possible, so I'm trying to find a way to do it

Thanks for the help, I'll continue to try to absorb the info you throw at me!

[piratepaul]

Hi, I will try to get it right, the weight and weight distribution are big factors in choosing a suitable motor.

For example, suppose you have a bicycle wheel and a car wheel, both are free to spin not attached to the car/bike, the torque necessary to turn the wheels is very different, different size motors needed.
Suppose you have a letter "T" and the motor is vertical at the bottom of the shaft of the "T" if there are weights at the two ends at the top of the T it will accelerate differently to if the weight was in the middle/centre top of the T.
If the weight is at the ends it will accelerate slowly, if the weight is at the centre it will accelerate fast. Like a fly wheel it must be balanced.
It is possible to calculate motor, current and acceleration of the sign, you need to do that to choose a motor and drive electronics.
I will try to help, but I need spec and need to think carefully... Its quite a tricky equation, the control is easy for me but might be tricky to explain.

I am on Vodafone mobile WiFi so don't do utube because it costs silly money to watch video on this tablet.

Tar&stuff.

[piratepaul]

PS ...its definitely possible.

Tar&stuff.

[Pauldf]

Or just have 3 limit switches, one at each point that you want it to stop?
Or a 3 pointed cam and one limit switch.
Then you can get away with using a normal motor