Servo Motor doesn't move although 5V

Hello Guys,

I dont get it anymore... I want to power a servo Motor with a 9V-Battery. So i bought an LDO which transfer it to 5V and max. 5A. Should be enough for a servo i think?

Well i tried it, and measure the 5V at the servo (so the circuit is correct!). Although the servo has 5V, it doesn't move! Why?! I think it doesn't flow a current.

If I power the Arduino with the 9V Battery (Vin), everything works fine. So where is the problem?

P.S. I use the Sweep-Example-Code for debugging.

The rectangular 9V batteries are for smoke alarms, not motors.

well thats no answer to my question :confused:

what would you suggest instead of a 9V battery?

and still the old question: why doesn't do the servo anything?

Are the grounds on the Arduino and the Servo's power source connected? If not, the pulses from the Arduino wont be read correctly.

Marsha

well thats no answer to my question :confused:

Let me try to be clearer:

A rectangular, 9V battery of the type used for smoke alarms cannot power a motor.

Solution: use a different battery. 6AA cells will power small motors for a while.
As the previous poster suggested, be sure to connect the grounds together.

I want to power a servo Motor with a 9V-Battery.

Servos are normally only rated to 6 V

Groove:
Servos are normally only rated to 6 V

Which is why he says in the next sentence that he was powering it through a 5v LDO....

MarshaJ847:
Are the grounds on the Arduino and the Servo's power source connected? If not, the pulses from the Arduino wont be read correctly.

Marsha

Thank you, that was the solution!

@Groove: I use a LDO?

@Others:

Well, i need to have a light-weight solution. Its a System on a drone, so it should be very light.
If I put four of this Batterys in serial, i should have 6V with 3000mAh, right?

Energizer Lithium-Batterie Mignon AA, 1,5V, 3000 mAh
(http://www.elv.de/energizer-lithium-batterie-mignon-aa-1-5v-3000-mah-4er-pack.html)

Do i need a LDO at 6V, or can i connect the 6V directly to Servos?

Also:
I measured this current consumption: 200~300 mA. So the solution with the battery-pack would keep up to atleast 10 hours?

The servos are okay with 6v.

Note that the Arduino itself is not. If you put it into Vin, the arduino will be getting 4.x volts, due to the dropout on the garbage regulator the Arduino boards use. But it's too much to supply direct to the 5v pin (you could use that LDO to get the 5v, and put the 5v output of that into the 5v pin - but if you do that, you must not connect it to USB while it's powered that way, lest you risk damage to the board)

DrAzzy:
The servos are okay with 6v.

Note that the Arduino itself is not. If you put it into Vin, the arduino will be getting 4.x volts, due to the dropout on the garbage regulator the Arduino boards use. But it's too much to supply direct to the 5v pin (you could use that LDO to get the 5v, and put the 5v output of that into the 5v pin - but if you do that, you must not connect it to USB while it's powered that way, lest you risk damage to the board)

Mhm im not sure if I understood what you tried to tell me :confused:

So i place 4x 1.5V in serial = 6V. THose 6V goes direct to the servos. Parallel to that, 6V goes to the Vin of the Arduino. Shouldn't be a problem, or? On my other arduino, i feed it with 9V into Vin. works fine.
I have readt, that Vin shouldn't be >12V, so the onBoard-LDO gets too hot and damages the board.

Well, i think i need special akkus for servo Motors? Btw: there are two servo-Motors to feed :confused:

Rachmaninow:
Mhm im not sure if I understood what you tried to tell me :confused:

So i place 4x 1.5V in serial = 6V. THose 6V goes direct to the servos. Parallel to that, 6V goes to the Vin of the Arduino. Shouldn't be a problem, or? On my other arduino, i feed it with 9V into Vin. works fine.
I have readt, that Vin shouldn't be >12V, so the onBoard-LDO gets too hot and damages the board.

Well, i think i need special akkus for servo Motors? Btw: there are two servo-Motors to feed :confused:

6V isn't high enough for the Vin of an Arduino. There is a forward voltage drop of 1V to 1.2V across the regulator.
Recommended voltage for Vin is 7VDC to 12VDC.

And 6V is too high for the +5V connection of an Arduino.

Unfortunately, 6V is right in the middle - in limbo.

Don't try powering the Arduino and servos from the same power source. Nearly all the problems
people have with servos are power related. Most servos need 1A or so peak, more than USB can
provide, much more than small 9V batteries can possibly supply, and servoe put spikes and noise
onto the supply that can damage or reset logic chips.

Motors/servos on one supply rail, logic on another (regulated and spike/dropout free) supply. Common
the grounds at the Arduino. Thats the key to trouble free behaviour.

Thank you for your answers.

I want to power the whole system by one Power-Supply.

So, I need a battery with big capacity, light and high current. Price doesn't matter. I connect this battery to the servo-motors via LDO (5V). Parallel to that, i connect it to the Vin of the Arduino..
So the battery has to be >7V?

Maybe, 5x AA (7.5V)? But its not a nice solution... there are a only attachment for 4x AA, not 5x.

Rachmaninow:
Thank you for your answers.

I want to power the whole system by one Power-Supply.

So, I need a battery with big capacity, light and high current. Price doesn't matter. I connect this battery to the servo-motors via LDO (5V). Parallel to that, i connect it to the Vin of the Arduino..
So the battery has to be >7V?

Maybe, 5x AA (7.5V)? But its not a nice solution... there are a only attachment for 4x AA, not 5x.

5 x AA isn't "big capacity", particularly if running two servos. And don't forget that your battery voltage will drop during discharge, so ideally you want 7V or a little less "at the end of discharge", not fully charged.

If I were you, and cost wasn't a concern as you say, I'd go with a NiMH or, better still, a Li-Po battery. 7.2V to 7.4V. They start out at 8V+, and drop to <7V when fully discharged.

How long do you want between recharges?
To determine battery capacity, you need to take that into account.
For 3 servos, the arduino itself and a few extra low-current peripherals, I use a 7.2V 4800mAh Ni-MH battery, which gives me a few hours between recharges. I've never taken note of the exact time - might be 4 hours.
(I recharge when the terminal voltage drops to about 6.5V or a fraction lower.)

Is your 5V 5A regulator linear or switching?

Thank you OldSteve, the first precise answer :slight_smile:

LiPo sounds nice, also a 7.4 Voltage is fine.
Well, i send sensorvalues via 433 MHz on this arduino, who shall controll 2 Servo-Motors. So with 4800mAh, it could be 4-5 hours? Sounds nice.
So i had a look on this battery:

Well, it has a nice capacity but its way too large and weights to much i think... :frowning: Never thought, that battery-management is so hard.

My 5V regulator is a linear one. "LM1084" (http://docs-europe.electrocomponents.com/webdocs/0780/0900766b807800b5.pdf)

EDIT:
I found this one:

its smaller than the other one, has more capacity

Rachmaninow:
Thank you OldSteve, the first precise answer :slight_smile:

LiPo sounds nice, also a 7.4 Voltage is fine.
Well, i send sensorvalues via 433 MHz on this arduino, who shall controll 2 Servo-Motors. So with 4800mAh, it could be 4-5 hours? Sounds nice.
So i had a look on this battery:

Uppps... Sie sind weitergeleitet worden !

Well, it has a nice capacity but its way too large and weights to much i think... :frowning: Never thought, that battery-management is so hard.

My 5V regulator is a linear one. "LM1084" (http://docs-europe.electrocomponents.com/webdocs/0780/0900766b807800b5.pdf)

EDIT:
I found this one:

Uppps... Sie sind weitergeleitet worden !

its smaller than the other one, has more capacity

Li-Po is as good as it gets in terms of energy density, (energy for weight/size). Both of those batteries sound fairly good.

With a linear regulator, you'll probably need a heatsink, especially when the battery is fully charged and the load is high. On my little robot, I currently use two LM2940CT-5 LDO linear regulators with small heatsinks, but have a 5V switching regulator on order, to reduce heat dissiaption and power wastage. That's for 3 servos, though - a higher load than your 2-servo project.

Nice okay.

So i will connect the Li-Po to the servos via LDO. Parallel to that, i connect it to the arduino (Vin). Also parallel to that, i want to power my 433 MHz module (Voltage increases range, 5V isn't very good). Maybe I can increase the voltage with this LDO:

http://www.exp-tech.de/pololu-12v-step-up-spannungsregler-u3v12f12?gclid=Cj0KEQiAycCyBRDss-D2yIWd_tgBEiQAL-9RkiuCb2OUDoP0vOXj4krR8xHNrMQWXvKkk9hAbmFbRksaAhMl8P8HAQ

to 12 V? So i get more range?

DrAzzy:
you could use that LDO to get the 5v, and put the 5v output of that into the 5v pin - but if you do that, you must not connect it to USB while it's powered that way, lest you risk damage to the board

This is curious. How could applying 5V to the VCC pin (whilst connected to USB) damage the board?

Rachmaninow:
Nice okay.

So i will connect the Li-Po to the servos via LDO. Parallel to that, i connect it to the arduino (Vin). Also parallel to that, i want to power my 433 MHz module (Voltage increases range, 5V isn't very good). Maybe I can increase the voltage with this LDO:

http://www.exp-tech.de/pololu-12v-step-up-spannungsregler-u3v12f12?gclid=Cj0KEQiAycCyBRDss-D2yIWd_tgBEiQAL-9RkiuCb2OUDoP0vOXj4krR8xHNrMQWXvKkk9hAbmFbRksaAhMl8P8HAQ

to 12 V? So i get more range?

That should give good range. Make sure you use good power supply filtering/decoupling though, to ensure there are no remnants of the switching on the output.
Are you sure you can't get enough range just with the 7.4V battery? You might not need to step up to 12V at all.
Having said that, though, I've had my best results by powering those cheap 433MHz RF transmitters from 12V. I use little A23 12V batteries in my alarm system remote controls - they don't get used very often so the battery lasts for months.

Mhm, yea i power the transmitter with 9V but its still not enough range. Maybe 20 Meters, without any walls - thats really poor. Also I use 17,3 cm long spiral-antennas (wire) at transmitter and receiver. Is it necessary to power the receiver with more than 5V to get a better range?

I also use this "cheap" 433MHz RF transmitters; i think the same like you. What did you do to extend the range?