Dedicated servo power supply


 

JIves

TVWBB Member
I'm working on adding a dedicated power supply for my servo as I'm using a larger servo and I want to up the reliability a bit. I've only had one brown out over a couple of cooks but it just makes me nervous.

I've been planning on using the NSR003A0X4Z module from GE Power which will take 4.5-14vdc in and output anywhere from .59v-6v at up to 3amps, which I think should generally be plenty for more or less any servo I would think about throwing at it. Mouser Link and the datasheet

I worked up this design from the data sheet and I'm just curious if anyone here that is smarter than I at power supply design had any thoughts or inputs on it.

I just used the schematic builder at digikey so it's pretty rudimentary but I think the salient details should be pretty apparent. I'm using a 2amp 12v source right now, if I add this on I'd likely go up to a 5 or 6 amp power source for the heatermeter overall.

HNAfepR.png



Thanks for taking a look, anyone see any problems here?
 
Man, it is irritatingly hard to find the .5% tolerance resistors in the values requested by the specs on these power modules. I've looked at a few modules and they all call for .5% tolerance, in the data sheets. It gets a little easier if I go SMD but the approach I was planning on taking here actually makes that kind of annoying.
 
Why wouldn't you calculate the actual current requirement of the servo (based on torque and speed) and just use an RC BEC circuit?
 
Why wouldn't you calculate the actual current requirement of the servo (based on torque and speed) and just use an RC BEC circuit?

I hadn't really thought of that being an option oddly. How would that get wired? I suppose now that I think about it, from a circuit perspective a BEC is effectively what I'm building here. I'm just not sure what a BEC expects to see on the yellow pulse wire. Would I just skip skip the wire and run red/black for the servo and yellow/brown from the HeaterMeter? It sure would be a lot less work.
 
Another thought, BEC's are designed to run off a battery, so I wonder if I'd still need to plan for a buffering cap on the power supply for the BEC still.
 
I fly a lot of R/C and I've not yet seen a BEC with a yellow pulse wire. All of mine 2 wire in and out. They typically have a fairly wide input voltage tolerance (~8V-26V) to allow them to be used with all the different LiPo cell counts in use. I've tried one on a wall wart and it worked fine. Also they're cheap as chips!
 
I've run a BEC right off my power supply no issues. Testing servo torque. I thought some of my very old BECs have a yellow wire. WIll have to dig into the parts box... And yeah, they are stoopid (tm) cheap now!
 
Are BECs typically non-isolated? meaning common ground with the rest of the circuit?

Any specific recommendations to try? I was looking at this one: http://www.amazon.com/exec/obidos/ASIN/B00MNBGDUA/tvwb-20 I like that it's user selectable for 5V or 6V (servo at 6V is preferable) I'm a little worried that it's going to be a decent quality.

The Castle ones seem to be the standard but you can't change the output without another device and then you're in like $50 for the BEC and the "Castle link"

Thanks for the input!

Edit: http://www.amazon.com/exec/obidos/ASIN/B000MXAR12/tvwb-20 this is where I'm seeing the yellow wire.
 
Typically yes since grounding in an RC plane is well, not easy. The ones from Hobbyking (Turnigy) are good. Not a Castle Creations but for 6 bucks?? Or the Hobbywing ones from Dx.com for even less. At that price it is worth a shot I'd say. Free shipping, too. As for the yellow - not sure why the signal wire is included on some.
 
The yellow signal wire is included for programming the BEC using a Castle Link. The only thing programmable on the CC BEC's is the output voltage and the only way to do this is to purchase the programmer.
 

 

Back
Top