Author Topic: servo switching motors on  (Read 5774 times)

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Offline jshalcottTopic starter

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servo switching motors on
« on: April 01, 2007, 11:02:38 PM »
so what a servo does is allow power to the motors, thus making them turn.
Well what does the servo switch and how does it do it.
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Offline Hal9000

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Re: servo switching motors on
« Reply #1 on: April 02, 2007, 04:05:32 AM »
A servo is not a motor

A servo is not built for continous rotation, and is at a certain angle depending on the square wave you feed into it. It has 3 inputs

A motor has 2 inputs and is built for continous rotation
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Offline ed1380

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Re: servo switching motors on
« Reply #2 on: April 02, 2007, 08:38:27 AM »
A servo is a little contraption with a geared down motor and control board with feedback


The servo control board provides power to the motors until they reach the desired position

The servo control board turns the motors on and off in the direction needed

A servo can be used in a way like a relay, where one of the horns would push a high-amp switch or whatever. In electric rc racing the servo pushes the knob of a large variable resistor to make it go forward or reverse, more or less acceleration
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Offline jshalcottTopic starter

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Re: servo switching motors on
« Reply #3 on: April 02, 2007, 10:35:58 PM »
where could i find one of these things
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Offline jshalcottTopic starter

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Re: servo switching motors on
« Reply #5 on: April 03, 2007, 10:19:14 PM »
i don't need a servo, and know what it is. Now what does the servo switch to turn on the battery. does it like swith an esc that is connected to a switch. I found this thing online, could this work.
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Offline trigger

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Re: servo switching motors on
« Reply #6 on: April 03, 2007, 10:22:45 PM »
i don't need a servo, and know what it is. Now what does the servo switch to turn on the battery. does it like swith an esc that is connected to a switch. I found this thing online, could this work.

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Offline jshalcottTopic starter

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Re: servo switching motors on
« Reply #7 on: April 04, 2007, 10:06:00 PM »
could this switch above be hooked up to a motor controller or something like that and the servo switches it off and on
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Offline trigger

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Re: servo switching motors on
« Reply #8 on: April 04, 2007, 10:11:39 PM »
could this switch above be hooked up to a motor controller or something like that and the servo switches it off and on

Yes, but I have no idea why you'd want to do that.  Waste of a servo.  If you want to control a motor with a servo-controlled switch, you're wasting components.  Send digital pulses to the motor controller with a microcontroller.  That's how it's done.  Or maybe I still don't understand what you're saying. 
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Offline jshalcottTopic starter

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Re: servo switching motors on
« Reply #9 on: April 05, 2007, 11:59:56 PM »
i'm trying to stay away from microcontrollers. I'm just wondering if i could use this, and if i did what would those three little plug thingies. would it hook up to a motor controller
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Offline ed1380

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Re: servo switching motors on
« Reply #10 on: April 06, 2007, 01:23:49 AM »
MCU>>>servo>>>switch>>>load acomplished
MCU>>>mosfet(s)>>>load acomplished

one is ground; another is power; and third is signal

Even if using a servo you'll use a IC of some sort
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Offline jsmoker

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Re: servo switching motors on
« Reply #11 on: April 06, 2007, 12:04:46 PM »
If you actually layout your application specifically you might get some more direct responses.  If you just want to control a motor you could buy an ESC as in controlling a throttle.  If you want to use the servo as a motor, you could modify it.  If you just want to use a servo as a switch, you could go with the two options in the previous post, or yank the motor in the servo and connect it to a relay switch.

As mention before the three connectors are ground, Vcc and Input.

The Input is PWM.  When the servo is still, it means the servo is at the position coresponding with the pulse.  A pulse 1.5ms long corresponds to the midway position of a servo.  1 or 2ms pulses correspond to the ends.  This is done by a means of proportional control within the servo.  The input of the control is changed via a potentiometer.  If you disconnect the potentiometer, make it stationary(glue it down), and tell the servo to go to the 90 deg position, the servo will continuously try to turn to get to the position cause the input doesn't reflect any changes.  I say "try to turn" cause usually there's a mechanical stopper on the last gear to prevent it.  Just make sure you're not drawing too many amps with a modifies servo.

Offline jshalcottTopic starter

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Re: servo switching motors on
« Reply #12 on: April 06, 2007, 08:37:48 PM »
in the esc do i need servos. if not what does it hook up to
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Offline ed1380

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Re: servo switching motors on
« Reply #13 on: April 07, 2007, 04:05:50 AM »
Is this whole thread about your rc robot?

i think then this'll work http://www.hobby-lobby.com/boatcont.htm 2nd from botom

http://www.rcdriver.com/articles/controllers.shtml
« Last Edit: April 07, 2007, 04:07:51 AM by ed1380 »
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