I'm looking to rotate an object (probably going to be an LED lighting system) at 60RPM.
I'm familiar with using Arduino, but haven't had any experience with RC electronics.
Should I be using an ESC and somehow program it to maintain this speed on a normal servo motor? Also is this relatively low speed possible? I'd say as long as it is accurate to about 20 RPM and doesn't go lower than 60RPM it would be fine.
Thanks Mike, that's perfect.
I never knew about slip rings.
PS is there any method available that would allow a range of speeds e.g. from 30 RPM to 300 RPM?
Those servos are continuous rotation, and vary their speed depending on how far away from the middle point the provided PWM value is. If it is above a certain value, it goes one way, below, it goes the other way. In the middle, it stops. The farther away from the middle point, the faster it goes. Unloaded speed of up to 70RPM when you use a 6v supply, up to 60RPM when you supply 4.8v
This is just one example, there are other servos like it if you need to vary your specs. At some point (80RPM?) it gets cheaper to use a different solution, but this is pretty easy and a modest price with simple control, and works directly with RC gear (TX/RX, you can use a pot or set up switch PWM values) or an Arduino or an APM.
Is it sensible to look at ESC's?
If you want very high speeds or want to use a step down transmission, maybe. Adds significant costs, and most off the shelf option will be in the thousands or tens of thousands of rpms, not tens or hundreds, if you just grab some at random.
Just check if the servo will support your rotation speed requirements. Most random servos will be just shy of hitting 60RPMs, and those spec'ed to hit 60RPM might not quite make it with a load. Which is why I chose one that is spec'ed for 70rpm. Since I'm guessing you might need to buy one, you might as well buy one that already does what you need, without needing to mod. But moding is fun, and if you are up for it, you can save some cash. Just get one that will be fast enough....
Thanks for your help.
Can you think of a way to maintain the same speed... I'm thinking if the batteries run down a little it will go slower, and ideally I would like some way for this to be maintained.
The continous servo is specified as moving fastest at 6V.
I am considering using a LM7086 voltage regulator and a 9V power source, and letting the voltage regulator output a constant 6V.
This should maintain a constant speed until the batteries run down significantly.
Can anyone see problems with this?
Ok checking out continuous servo mod, thanks :)
Meh just realised I'm going to need to use a Arduino controller to send PWM to this continuous servo. I only want it to go at full speed. Would connecting the PWM to DC to make it 100% send it at full speed?