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Author Topic: using two servos with BASIC stamp microcontroller  (Read 3186 times)

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Offline dmehlingTopic starter

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using two servos with BASIC stamp microcontroller
« on: July 04, 2008, 12:30:16 PM »
I have a basic stamp microcontroller on a development board that has been set up to operate a servo.  The power supply of the development board is wired up to an LM7805 5v voltage regulator which is in turn connected to the servo.  I am wanting to know how I would connect a second servo.  Can I use the same voltage regulator and simply run additional wires to the power inputs of the other servo?  I know the voltage regulator can handle up to 1 amp, and the peak current of both servos running simultaneously would be less than 500 mA, so I don't think I would ever overload the power supply.

Offline izua

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Re: using two servos with BASIC stamp microcontroller
« Reply #1 on: July 05, 2008, 02:24:10 AM »
It won't overload the power supply, it would overload the voltage reg, which has thermal protection built in. So if they are doing a lot of motion with some opposing force, the regulator will cease working intermittently
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Offline dmehlingTopic starter

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Re: using two servos with BASIC stamp microcontroller
« Reply #2 on: July 05, 2008, 08:42:04 PM »
I wouldn't think the voltage regulator would be overloaded since it can handle 1 amp and both servos running simultaneously wouldn't even approach that.  As far as wiring, do I run additional leads from the voltage regulator to the header for the second servo, or can I wire that servo header to the header for the first servo?

Offline dmehlingTopic starter

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Re: using two servos with BASIC stamp microcontroller
« Reply #3 on: July 07, 2008, 12:38:33 PM »
At this point I'm not too worried about voltage and current.  Both servos will be doing very low power applications and will not be running simultaneously.  What I'm trying to figure out now is how exactly to connect the second servo.  I have a positive lead running from the regulated output to the positive pin on the header of the first servo.  From that pin can I run another lead to the positive pin on the header of the second servo?

Offline airman00

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Re: using two servos with BASIC stamp microcontroller
« Reply #4 on: July 08, 2008, 10:39:20 AM »
Stall current of a servo can be around 1 amp!

and do not regulate voltage to a servo!

http://www.societyofrobots.com/actuators_servos.shtml#regulate
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Offline dmehlingTopic starter

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Re: using two servos with BASIC stamp microcontroller
« Reply #5 on: July 08, 2008, 01:38:42 PM »
I think you're taking that information on servos out of context.  How else can I provide the right amount of voltage to my servo unless I regulate it?  It seems like the only instance where you would not need to is if you are using a battery that supplies voltage within the range acceptable to the servo, but batteries are pointless for my project.  I have a 12 V adapter so I obviously have to regulate.  I already have one servo set up this way and it is working fine.  As far as having too much amperage, I will not be running both servos simultaneously so if they ever reached stall current (which would probably never happen) it would only be one servo.

Offline airman00

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Re: using two servos with BASIC stamp microcontroller
« Reply #6 on: July 08, 2008, 02:51:02 PM »
I think you're taking that information on servos out of context.

nope

Standard analog servos at 6V have a stall current of around 1 amp, test it out yourself if you dont believe me.


Also make sure you use a switching regulator , so you don't lose any power and so that way you are efficient
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Offline dmehlingTopic starter

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Re: using two servos with BASIC stamp microcontroller
« Reply #7 on: July 08, 2008, 03:28:20 PM »
I was not saying a servo will not reach 1 amp.  I was saying that in my particular application, my servos should not have to reach anywhere close to stall current.

Offline airman00

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Re: using two servos with BASIC stamp microcontroller
« Reply #8 on: July 08, 2008, 03:43:20 PM »
I was not saying a servo will not reach 1 amp.  I was saying that in my particular application, my servos should not have to reach anywhere close to stall current.

ok sounds good.

make sure you don't touch the regulator , it can get really hot and you'll get a nasty burn   :o
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Offline dmehlingTopic starter

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Re: using two servos with BASIC stamp microcontroller
« Reply #9 on: July 08, 2008, 03:49:23 PM »
Should I get a heat sink?

Offline airman00

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Re: using two servos with BASIC stamp microcontroller
« Reply #10 on: July 08, 2008, 03:50:41 PM »
Should I get a heat sink?

either that or get an efficient switching regulator

or dont touch it ,  :D


seriously if it gets to hot it will automatically shutdown (if it has thermal shutoff feature)
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