First off, I'm new to Arduino and I was only ever taught basic electronics back in high school, most of which is a blur. I'm trying to build an animatronic spider with 12 x SG90 micro servos moving the leg mechanisms. My problem is power 12 servos simultaneously. From what I know the servos run on 4.8 volts and that I shouldn't go over 6 volts for powering them. I have also been allowing 1 amp for each servo motor, meaning I need to supply 12 amps with only 6 volts for the servos to run at full torque if required. I have only ever run two servos before simultaneously using the 5V power outlet on the UNO R3 controller board which worked fine, but from my research trying to do that with 12 servos would fry my board and it wouldn't be able to supply 12 amps anyway. I then started looking at external power sources, starting with AA batteries, using 4 AA batteries (Roughly around 6 volts) to power 12 servos (I know, this was a stupid thought). When I realised that wouldn't work I thought what if I split the 12 servos into groups of 3 and powered 3 servos together using 4 AA batteries for each group, and wire all these separate battery holders into the GND outlet on the controller board. But then I wouldn't know how long that would last when running and if it would work at all since 3 amps is still a lot for 4 AA batteries. A friend recommended to me I should look into step up/down transformers which led me to find this LED switching power supply (Data sheet for this is attached below, I'm specifically talking about the LVP-100-5 model) which can be hooked up to the mains and has an output of 5V and a current range of 12 amps, which sounds like it would be suitable but I am no where near an expert, plus I'm not sure if it would work with servos since it's meant for LED's. Honestly, if none of my ideas are feasible, I could really used some advice or at least something to point me in the right direction. I have looked at a lot of forums asking the same thing I am, but I really couldn't understand a lot of what was being talked about. Would be really grateful for any advice
You COULD sent signals from a regular Arduino UNO to 12 servos if their power pins are supplied from an external 5V to 6V supply. BUT how many OTHER arduino pins do you need for other things on your project. UNO has:
12 Digital I/O pins (usuall pins 1 nd 0 dedicated to programming)
plus
6 "Analog" pins that CAN also be used as digital In out Out
So 18 or so...
To connect the servos and supply them with a separate power supply the easiest way is to use a "Sensor Shield" that plugs on an UNO and has a separate terminal block to supply external power to the power pins. Like this:
The SG90 servos have a stall current of around 650 mA. If not all will be moving at once, you could probably get away with a 5-6V, 5 A power supply for all servos.
Freshly charged AA NiMH batteries can supply 2-3A, so perhaps two 5xAA packs in parallel.
Wizard357:
First off, I'm new to Arduino and I was only ever taught basic electronics back in high school, most of which is a blur.
I'm trying to build an animatronic spider with 12 x SG90 micro servos moving the leg mechanisms.
My problem is power 12 servos simultaneously.
From what I know the servos run on 4.8 volts and that I shouldn't go over 6 volts for powering them.
I have also been allowing 1 amp for each servo motor, meaning I need to supply 12 amps with only 6 volts for the servos to run at full torque if required.
I have only ever run two servos before simultaneously using the 5V power outlet on the UNO R3 controller board which worked fine, but from my research trying to do that with 12 servos would fry my board and it wouldn't be able to supply 12 amps anyway.
I then started looking at external power sources, starting with AA batteries, using 4 AA batteries (Roughly around 6 volts) to power 12 servos (I know, this was a stupid thought).
When I realised that wouldn't work I thought what if I split the 12 servos into groups of 3 and powered 3 servos together using 4 AA batteries for each group, and wire all these separate battery holders into the GND outlet on the controller board.
But then I wouldn't know how long that would last when running and if it would work at all since 3 amps is still a lot for 4 AA batteries.
A friend recommended to me I should look into step up/down transformers.
Which led me to find this LED switching power supply (Data sheet for this is attached below, I'm specifically talking about the LVP-100-5 model).
This can be hooked up to the mains and has an output of 5V and a current range of 12 amps, which sounds like it would be suitable but I am no where near an expert, plus I'm not sure if it would work with servos since it's meant for LED's.
Honestly, if none of my ideas are feasible, I could really used some advice or at least something to point me in the right direction.
I have looked at a lot of forums asking the same thing I am, but I really couldn't understand a lot of what was being talked about. Would be really grateful for any advice
Sorry I had to spread out your questions into point form.
Tom....
Lipo batteries are great in delivering high current and are lightweight compared to other batteries.
However they are sensitive creatures,if you overcharge then they might selfdestruct and blow up,same if you discharge them to much.
So you would need a decent charger. And also a low voltage cutoff. And some step down module since a single battery has a to low voltage and a 2s (2 in series) has a to high voltage.
In the end the good old nimh will probably be the easiest. Changes are you have a charger for them already laying around the house and tond of battery holders to be found for them
jremington:
The SG90 servos have a stall current of around 650 mA. If not all will be moving at once, you could probably get away with a 5-6V, 5 A power supply for all servos.
Freshly charged AA NiMH batteries can supply 2-3A, so perhaps two 5xAA packs in parallel.
So if I used 4 AA NiMH batteries in each holder and had 4 of these holders, each holder powering 3 servos that would in theory provide enough power to run all the servos. Would you say they would last an hour for each charge or less if they were using full torque (They probably won't but I want to be prepared)? Also, if I switched to a Pololu's Maestro servo driver, wouldn't channelling that much current through it damage the board? Would I need to power the servos externally from the board and only connect the GND and PWN wires to the board like the Arduino UNO R3 board? I know that using a Pololu's Maestro board will make moving the servos easier so I can easily create a walk cycle with the servos, but unsure of how much voltage and current it can handle.
had 4 of these holders, each holder powering 3 servos
I suggested two 5xAA NiMH holders, but more wouldn't hurt.
Also, if I switched to a Pololu's Maestro servo driver, wouldn't channeling that much current through it damage the board?
No. The Pololu engineers are quite competent. But you could read their extensive documentation to be sure.
unsure of how much voltage and current it can handle.
The extensive Maestro user guide is BY FAR your best source of information. You will find that to be generally true, if you buy from a reputable manufacturer and then take a little time to educate yourself.
