Go Down

Topic: powerfull servo board for 16 high end servo's (Read 350 times) previous topic - next topic

iejun

Hi all,

Am struggling with the Adafruit 16x servo board. I connected 16x 1,8 kg servo's but they arent just that powerfull enough. So i want to gain the stronger ones ..11,8kg. I know that the Adafruit board cant spin them more than 6 ...so am kind of stuck here...can i power them externally and drive them with a Arduino Mega ? Or are there powerfull servo boards on the market because i cant find any.

Was looking at these
https://www.kiwi-electronics.nl/mg996r-digital-metal-servo


cheers Ian

slipstick

I don't know what "can't spin them more than 6" means but if it really is a problem then you don't really need a servo board.

The servos can be powered directly from a battery/power supply with just the signal wires connected to the Mega, which has enough digital pins for 16 servos.

Steve

iejun

#2
May 18, 2018, 10:05 pm Last Edit: May 18, 2018, 10:08 pm by iejun
aa ok. what psu would you reccomend ? I mean i dont want to burn down or damage the servo's ...do i need to add a regulator for each servo channel ?

Wawa

That Adafruit servo board is mainly generating the SIGNALS for the servos (PCA9685 chip).
That part has nothing to do with servo size/power.

That board also connects servo POWER/GROUND to the servos (from the 2-pin screw terminal to the servo pins),
and IMHO the board traces are already borderline for the total stall current of 16 tiny servos.

The real Adafruit version also has a reverse protection diode/mosfet with an absolute max rating of 25Amp in series with servo POWER(+).

If you are using that board with bigger servos, then the obvious solution would be to solder the (thick) servo supply wires (from the servo power supply) directly to the relevant traces (power and ground) of that PCA board.
Leo..

iejun

#4
May 19, 2018, 08:47 am Last Edit: May 19, 2018, 11:48 am by iejun
so you mean i can still use the adafruit boards but only the signal wire and route the powerwires to an external powersupply ? I only could manage to run only 6 big servos directly from the board.

What do you mean with the Real adafruit board ?

Do i still need to ground all 16 servo pins from the adafruit board ?


And would my servo's be safe with a external powersupply ?

Could i use this one ?
https://www.ledtuning.nl/en/shop/product/917/power-supplies/5-volt-open-frame/led-power-supply-open-frame-5-volt-50a-350-watt

cheers ian

Wawa

Don't know what the power/ground traces of ebay clones look like.
Ebay clones also don't have the mosfet protection diode.

Don't confuse the 5volt PCA9685 supply with the servo (motor) supply.
You need 5volt and ground from the Arduino to power the servo board.
And 5-6volt from a powerful external supply to power the servo motors.

Stall current of the six servos from post#0 is 6*2.5Amp = 15Amp.
Just make sure the servo motor supply can deliver that.

A 50Amp supply is overkill if you 'only' need 15Amp.
Leo..

slipstick

But if you're intending to use 16 x MG996 servos as the initial post says then 50A is reasonable. But if you're looking for maximum torque from those servos note that you only get 11kg.cm at 6V. It's only about 9kg.cm at 5V so I'd look for a 6V power supply.

If you want to run 16 servos without using 16 pins then the Adafruit board will work with separate servo power. The grounds from the servo power supply, the Adafruit board (just one connection because they're all commoned on the board) and the Arduino need to be connected together.

But you do need to decide which way you're going with this because the code for the 2 versions with and without the board will be different.

Steve

iejun

yeah indeed ...i think am going to try using the board with the same code but with external psu ...thx for tips guys

Go Up