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Servo on separate power supply

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(@bobbruch-2)
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Joined: 3 years ago

Hello

Does anyone know what the current draw is for the servos?

When we had the servo drawing the same power as the bluetooth we were continuing to get the broken pipe error.  So, we have been trying to run the servo off of a separate 9v battery.  It seemed to run fine when we ran it at 9v but we were concerned that it would eventually be unhappy running so far out of it's voltage range so we only had it plugged in for a few seconds.  It still works fine on other arduino boards so we know we didn't fry it.

When we use a voltage divider to drop things down to 5v the servo won't work.  We know that the voltage divider is impacting the current but we cannot seem to find a good combination of resistors that will allow the servo to run.  If we go to high on the resistors (820 and 1000) we assume we are dropping the current too low for the servo but if we go low on the resistance (1 and 1.2) the resistors get so hot that they will have to burn up.  

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(@compase)
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Joined: 17 years ago

While I haven't measured the draw, similar servos of that size *should* only be drawing 100-250mA. See https://www.rcgroups.com/forums/showthread.php?828495-Current-draw-of-micro-servos .

The Nano Every has a pretty stout voltage regulator and should be able to handle this draw without a brown out. 

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Posts: 8
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(@bobbruch-2)
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Joined: 3 years ago

We are trying to create a completely separate power supply with a 9 volt battery to avoid the servo/bluetooth "pipeline" error that we keep getting.  

Is there some way to connect the 9 volt battery through the board to take advantage of its regulator while keeping it separated from the bluetooth power draw?

Or can we just run the servo at 9v and hope that it has internal safeties?

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(@hapkidon)
Joined: 3 years ago

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Posts: 5

@bobbruc

You can run a nano off a nine volt battery.  The positive terminal of the battery goes to the Vin pin.  The built regulator will manage it. 

 I would however, be hesitant to run a servo on a 9V battery.  It will (eventually) burn out the servo.    I would use 3 AA/AAA batteries (in series that would give you 4.5 volt).    Just connect the ground from the battery pack to the GRD pin on the arduino as well as Ground on the motor

 

 In the past we have used this something like this, but you should be able to 3d print one as well

https://www.amazon.com/Onwon-Pieces-Battery-Holder-Storage/dp/B07M8RV9DC.

 

Don

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