Variable Speed Rotating Platform HELP!

[RoyalKensington]

Hi, so I'm new and I just wanted to ask about building some kind of rotating device. I'm a totally electronically illiterate, so please forgive me.

I'm working on a video project and for one shot I want to have the camera in the centre of a circle of people, with the camera rotating in place. I had tried using a turntable (record player) but it spun too quickly and the filmed images were blurred. I tried a number of ways of slowing down the rotation eg: putting weights on the turntable, wedging cards under the turntable, slowing it with my finger but it was hard to get a constant speed. Manually turning the turntable has the same problems!

Is there a device, like an electric motor I could use that allows me to set/control the speed of rotation? I've racked my brain/s and can't come up with anything and the shot is absolutely critical to the project! Aahhh! Anyone know anything that could be useful?

 

[Someone Electro]

Get a disco ball and hang the camera from the string isnted of the ball?

 

[RoyalKensington]

Hmmm...maybe though I'm not certain suspending the camera is going to be stable, I need a very solid locked in rotation, no wavering up and down, just around on the central axis.

Is there not something like a stepper motor? I'd be greatful if someone could give me even some keywords to search out for...I literally don't know anything about this type of equipment!

 

[Someone Electro]

Well you just have to steady the camera, it wont swing up and down from the rotation just if the base moves.

Anyway yes a stepper motor would be a good solution.But note that stepper motors need electronics to get going.What it basicly dose is pulse 4 windings in the right order the faster you do that the faster it spins,since each of these pulses thurns the motor a exsact number or degrees(how many depends on the motor) The down side is that they are normaly pretty noisy

A nother solution is a DC motor with a rpm counter so its regulated to a constant adjustable speed.The quick way of regulating it is to simply put a nother DC motor on the same shaft and meshure its output voltage.

 

[3v0]

Check the surplus supply and robotics places, they often have DC motors that are geared down. Look for gearhead and gearmotors. Do you have a given RPM in mind?

To some degree you can change speed by changing the voltage. For example if you found a 12V 5RPM motor running it at 6 volts may give you a speed or 2RPM. Do not expect it to be linear.

I am thinking a stepper motor would be too jerky.

 

[arhi]

I am thinking a stepper motor would be too jerky.

L297 + L298N combo can do half stepping and with a decent stepper motor (10+ steps per full rotation) it should turn smooth .. anyhow, without stepper or servo I do not see how you can achieve controllable and steady RPM. If speed does not need to be precise, then any geared motor will do.

 

[3v0]

L297 + L298N combo can do half stepping and with a decent stepper motor (10+ steps per full rotation) it should turn smooth .. anyhow, without stepper or servo I do not see how you can achieve controllable and steady RPM. If speed does not need to be precise, then any geared motor will do.

I do not know much about steppers.

Once a DC gearmotor is up to speed, it should provide uniform speed if the load is balanced.

The OP describes himself as "electronically illiterate". Changing speed by adding or removing a few cells is something he could do. Setting up a stepper motor may be too advanced.