I'm looking for guidance on how one would approach powering numerous servos that require a voltage that's not a common one provided by power supplies (that plug into an outlet, vs. batteries)
I can find plenty of power supplies (that plug into an outlet) on Amazon that output 12V or 5V with high current (eg. 30A up to 100A), which would be completely fine if my servos required 5V, but say they don't... instead, requiring 6V, 6.8V, or even 7.4V. I cannot, for the life of me, find any power supplies that output any of those voltages with a high current, whereas 12V and 5V are a dime a dozen.
I've been trying to research (I'm still relatively new to electronics), and the solutions I've come across - such as voltage regulators, DC to DC, etc. - all seem to adjust the voltage properly but also severely limit the max current output, and because I'm powering some hungry servos, I can't afford to lower the available current.
A power supply like this would be wonderful, Amazon.com except it outputs 12V.
So how would you guys approach this? Consider I have 10 servos, let's say each one is a ZOSKAY 6V 20kg servo which requires 6.8V. I also have a PCA9685 servo board to connect all the servos to, receiving commands from an Arduino Mega on the I2C bus. The last bit of the puzzle would be finding a power supply to power just the servos that can output 6.8V and 30A (can't find a spec sheet for how much current the ZOSKAY servos draw, but I'm just overshooting for now). And hypothetically, say I'm using 10 servos that require 7.4V instead, or even 6V. Any suggestions or potential topics to further research?
Welcome to the Arduino forum. As you gain more experience in electronics, you will learn how easy it it to reduce a voltage to what you need. Find a power supply that will provide the current you need, say 24 volts DC. Then find an adjustable buck converter that will handle 24 volts input and the current you need. Adjust it's output to the voltage you need for your servos.
mrbanana103:
let's say each one is a ZOSKAY 6V 20kg servo which requires 6.8V.
You might have understood that wrong.
That servo requires according to it's specs 4.8 to 6.8 volt.
6.8volt is absolute max.
A (safe) voltage range in case you use a battery to power the servo (think 6volt lead/acid).
A 5volt regulated supply is perfectly fine.
You make it easier for the servo at the cost of loosing a bit of torque.
Most metal frame 5volt supplies can be turned up to 5.5volt (or more) with a trimpot near the terminals if you must squeeze some more out of it.
Leo..
You could get a hefty 12v power supply, then get one or more 6v UBEC voltage converters to reduce the 12v to 6v. In the RC world the UBEC is used for powering servos from higher voltage batteries. You can find them on ebay starting at about $2 and up.
A UBEC is basically just a shrink-wrapped switch-mode DC-DC converter (sometimes with an inflated price).
I just had a look on EBay and there are dozens of 30A buck converters available with adjustable outputs. Even if for some reason you have trouble finding one with high enough current rating you can always split the servos into groups and use several converters t power them (just remember to connect all grounds together).
In an RC model the radio receiver and servos are typically powered from a 2S LiPoFE4 pack (6.6V) or a 5 cell NiMH pack (6V), or sometimes a 2S LiPo pack (7.4V).
Most servos are not rated for 7.4V, hence the LiFePO4 battery with its lower voltage.
Basically servos are not designed for RC models which traditionally did not use 5V. 6V and 7.2V were common (5 and 6 cell NiCd packs). LiPo hadn't been invented and an RC plane's prop motor was a glowplug petrol motor.
So 6V and 7.2V are the commonest ratings for servos.
There days some are appearing able to run from 2S LiPo (ie 7.4V nominal). LiFePO4 packs are good substitute for heavy NiCd/NiMH, and they are 6.6V for 2S.
In fact the commonest voltage rating for hobby servos, most of which were designed for model aircraft use, is 4.8V because almost everyone used 4 x NiCd and later NiMH cells. That's also why most ESCs have 5V BECs.
Most will tolerate 6V. But it's only recently that servos have also been specified for 2S LiFePO4 or 2S Lipo packs and even now it's mainly the larger servos. Micros are still 4.8-6V.
So the moral of the story is check the specification for the actual servo you're using! E.g. if you try a 2S Lipo (8.4V fully charged) on a little SG90 it may not survive the experience.