One motor works while another similar one does not? Current related?

Other Hardware Motors, Mechanics, Power and CNC
1

Hi all,
I'm having a little trouble getting a servo I recently purchased to work how I would like.
I originally bought a cheap smaller servo to test everything out with and had no problems at all, this was the Futaba S3003, which can be found here http://www.futaba-rc.com/servos/analog.html.

However now that I've purchased the larger motor that I will use, it behaves quite strangely and I'm not sure why.
This motor is the Savox SV-0236MG, which can be found here http://www.cmldistribution.co.uk/cml_product.php?productId=0000006204

When this motor is plugged in the serial LED flashes very quickly, stopping only momentarily for the blue light next to the PM port to flash, before the red light begins to flash repeatedly again.
While this happens the serial output is blank.

This is compared to when the Futaba is plugged in, when the output in the serial port is as it should be, and the serial LED only flashes every 2 seconds, which is the delay programmed into the loop.

I'm unsure if I'm missing a major difference between these two servos which is causing the different behaviours, but I'm having trouble finding this if there is. Perhaps the amount of current being drawn for the larger motor is too high?

Any input at all would be a great help and hugely appreciated.

Thanks.

2

If you are powering the servo from the Arduino +5V, don't. That almost always leads to trouble. Use a separate power supply and be sure to connect the grounds together.

3

'm unsure if I'm missing a major difference between these two servos which is causing the different behaviours, but I'm having trouble finding this if there is. Perhaps the amount of current being drawn for the larger motor is too high ?

Don't be offended , but what you are missing is a basic understanding of electronic and mechanics.
FACT-1
The large servo is designed to run of voltages between 6V and 7.4V .
FACT-2
It is a METAL-GEAR servo , meaning there are no plastic gears connected to feeble motors to limit the current. Even small plastic
gear servos can draw more than 1A in a stall (jammed).
The large servo would easily pull your 5V down even without stalling. (I would expect)
That servo needs it's own power supply an it would have to be a 6V walwart that can handle several amps.
You could get by with a 6V ,1A walwart until you put a load on the relay (connect the arm to something) but once you have a load you would need at least 2 or 3 amps.

4

Not at all, I appreciate the responses, thank you both.

5

Would it not be possible to simply rewire the wires providing power to the servo directly to a 12V battery?

6

Would it not be possible to simply rewire the wires providing power to the servo directly to a 12V battery?

DON'T DO THAT UNLESS YOU WANT TO FRY THAT EXPENSIVE NEW SERVO ! (Vin =6V -7.4V)

7

I appreciate the urgency there!
I assume I would need some sort of power module the control the voltage coming through it, like this one which I will already be using [u]https://store.3drobotics.com/products/apm-power-module-with-xt60-connectors[/u], but one with a higher voltage cap?

8

Can you use anything on this page ?
https://www.google.com/search?q=6v+3a+power+supply&rlz=1C1GPCK_enUS504US504&oq=6V+3A+&aqs=chrome.1.69i57j0l5.12094j0j8&sourceid=chrome&es_sm=93&ie=UTF-8

9

I expect many of them would work however I'm unsure how difficult it would be to adapt them to attach to both the battery and the servo motor. Do you have any insight into this?

10

This is what I would use , running off a 12V motorcycle (or motor scooter) battery or 12V Gel-Cell battery.

http://www.ebay.com/itm/DC-DC-3A-Buck-Converter-Adjustable-Step-Down-Power-Supply-Module-LM2596S-/181400104288

Specifications:
Input: DC 3V to 40V (input voltage must be higher than the output voltage to 1.5v above can not boost)
Output: DC 1.25V to 35V voltage continuously adjustable, high-efficiency maximum output current of 3A.
PCB size: 45 (L) * 20 (W) * 14 (H) MM (with potentiometer)
Adjustment using the 3296 adjustable resistance.
The characteristics of the low price, small size, and relatively simple function.

IN + input positive IN-enter negative!
OUT + output the positive OUT-output negative!
Note that the input and output can not be reversed. Reverse may burn out.

Alternately ,
http://www.ebay.com/itm/DC-DC-Buck-Converter-Adjustable-Step-Down-Breadboard-Power-Module-1-25V-36V-5A-/231216889753

1?Input voltage range:4?38VDC(Note:input voltage not exceeding 38V)
2?Output voltage range:1.25-36VDC adjustable
3?Output current: 0-5A
4?Output power: 75W
5?High efficiency up to 96%
6?Built in thermal shutdown function
7?Built in current limit function
8?Built in output short protection function
9?Input reverse polarity protection: None (if required, high current diode in series with the input).
10?L x W x H =5423.817.6MM
11?Weight: 16g
Note:Some customers report: "The module can not adjust the output voltage is always equal to the input voltage." When you encounter this problem, please counterclockwise rotation of the potentiometer 10 laps or more, then use the module you can adjust the output voltage. Because the factory default output voltage of about 20V.

11

Seems to be just what I'm looking for!
And these are simply wired between the battery and the servo itself?

12

Look at the photos. See those holes in the corners with solder on them ? See the IN+/IN- and OUT+/OUT- ?
See the little blue trimpot for adjusting the voltage ? You can get some brass hardware and ring terminals and you're good to go.
Don't use any non-brass hardware. (trust me. I'm a professional).

I guess I don't have to tell you to adjust the voltage to 6V BEFORE connecting the servo, right ? (the converters are shipped with the output pre-adjusted to 20V) That would be bad.... =(

FYI- FOR $5 , I WOULD GET THE 5A BECAUSE THE INDUCTOR IS LARGER AND IT HAS A HEATSINK

13

Sorry to say it turns out I was mistaken and there are in fact two 6V batteries connected in series to make 12V.
It was possible to rearrange the batteries into parallel leaving me with 6V out.
Is it as simple as connecting the positive and negative of the battery to the two wires that would match to + and - on the Ardupilot ports? With the remaining signal wire being plugged into the Ardupilot as was before?

14

This is the first time you mentioned the ardupilot . Please post a vendor link or some documentation for that.
I think the answer to your question is yes but I would rather wait until I know what you are talking about.