16 Channel Servo Driver w/2-wire Actuators??
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16 Channel Servo Driver w/2-wire Actuators??

by siforek on Thu Jan 17, 2013 4:29 am

First off I'm sort of a n00b with this stuff...

Got everything in the tutorial here: http://learn.adafruit.com/adafruit-16-c ... pberry-pi/
Working good upto the point where I was trying to use these: https://solarbotics.com/product/gm10/

As any non n00b probably can tell it's not working. I wanted fast motors, didn't realize or quite understand PWM at the time of ordering everything & wanted to know if there's any way to get these working with the 16 channel? Even if it takes considerable rewriting of the python libraries?

Thanks in advance :)
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Re: 16 Channel Servo Driver w/2-wire Actuators??

by adafruit_support_bill on Thu Jan 17, 2013 6:14 am

These motors are fundamentally different than servo motors. Connecting them directly to the PWM outputs is likely to damage the board.

There are a couple ways to approach driving them from this board. Both involve additional circuitry. What exactly do you want to do with these motors? Do you want just speed control, or do you need direction control too?
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Re: 16 Channel Servo Driver w/2-wire Actuators??

by Buken on Fri Jan 18, 2013 2:25 am

I am responding for siforek. we are working together on this. here is a link of basically what i need the motors to do. http://david.neonquill.com/projects/cam ... index.html. so it is either we go about more circuitry or maybe a servo? we will see what you have in mind.
thank you.
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Re: 16 Channel Servo Driver w/2-wire Actuators??

by adafruit_support_bill on Fri Jan 18, 2013 6:18 am

That is a nice looking doorbell project!

Using those motors, you don't need direction control, since they have a built-in return spring. You also probably don't need speed control. I expect you will want the actuators to be as quick as possible.

You could use a darlington array to drive the motors: http://adafruit.com/products/970
And control the darlington array from the PWM board. Although, that would be overkill if you are not using the PWM to actually control the speed. Another option would be to drive the darlingtons from a port-expander: http://adafruit.com/products/732

The simplest option would probably be to go with some micro servos using the PWM controller you have.
https://www.adafruit.com/products/169
https://www.adafruit.com/products/1143
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Re: 16 Channel Servo Driver w/2-wire Actuators??

by Buken on Fri Jan 18, 2013 7:14 pm

we are using a Rspberry pi and need it to be fast with little to no motor noise. there will be 12 motors.
thanks.
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Re: 16 Channel Servo Driver w/2-wire Actuators??

by adafruit_support_bill on Sat Jan 19, 2013 6:45 am

I don't know how quiet those pager motors are. Servo speed and noise depends mostly on the quality of the servo. Servos from HiTec or Futaba servos are some of the best.
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Re: 16 Channel Servo Driver w/2-wire Actuators??

by Buken on Wed Jan 30, 2013 12:35 am

Ok support.
It does look as if servos will be the best bet being that we will also be able to control speed. however my next question is servo noise. No noise would be preferred while in idle and running. I've read that capacitors can help. any suggestions? thanks.
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Re: 16 Channel Servo Driver w/2-wire Actuators??

by adafruit_support_bill on Wed Jan 30, 2013 7:08 am

Since you will have no load on them when idle you can stop sending the PWM pulses and they will be silent. In motion, there will be some audible motor & gear noise. Capacitors can reduce the electrical noise, but they won't do much to reduce the audible noise. In my experience, the high-quality servos tend to be quieter than the low-cost versions. HiTec and Futaba are two of the better brands.
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Re: 16 Channel Servo Driver w/2-wire Actuators??

by Buken on Wed Jan 30, 2013 12:41 pm

ive takin your advice and been looking at those two brands. i also read that analog are quieter than digital. do you know?
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Re: 16 Channel Servo Driver w/2-wire Actuators??

by adafruit_support_bill on Wed Jan 30, 2013 4:24 pm

My experience has been that they were about the same. But I have not used very many different models of the digital servos.
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