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i need help changing voltage from 5-6v to run my servoes from my servo controller that runs at 5v 1a? Answered

hello all i am going to be running 4 servos from this servo controller. it uses a 5v 1amp power and i would like to run my servos at 6v is there a way to do this?  i was thinking not sure if its possible but 5v to controller circuit and 6v to servos  and leave the signal wire connected to controler..

here is the Data Sheet 

2. i feel dumb but my second ? is on a potentiometer do i hookup the middle pin to signal outer left to 5+ outer right to ground sorry just want to make sure i get it right.

thank you

Discussions

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-max-

4 years ago

You can use a boost converter to power the servo.

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AndyGadget

7 years ago

 
The vast majority of servos run perfectly well on 5V, with some loss of torque.  Unless you are pushing them to the max, everything will be fine.
If you really need to do it, connect the 6V supply positive to the servos, the +5v to the circuit and connect the grounds (0V) together. 
Your wiring for the pot is correct.

Just a rider to that - It is better to run servos and circuitry from different supplies as servos do take large peak currents from the rail and can cause problems if the supply is not up to it, but for experimentation and if you're using servos under 40g or so you shouldn't get a problem here.  There is a 2200uF capacitor on the controller which will help with this.

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AndyGadgetAndyGadget

Answer 7 years ago

 
I've just looked at your other question and see it is a serious application and you are planning chunky servos, so I'd say definitely use a separate supply, connected as I suggested, and with it's own large capacitor.  I'm guessing it will need to be capable of providing a couple of amps.
Are you using a setup like SteveAstro suggested in the other question?
(Steve is definitely the guy for advice on a project like this.)


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skullkeeper80AndyGadget

Answer 7 years ago

yes im using the setup steve suggested. i sketched up a pic

1. do i have everything correct

2. with or without cap? if with what size and where does it go, and what polarity?

3.  6v 1.5a  or 6v 2a  for 4 servos only 1 will be used at a time

servo controller hookup.jpg
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AndyGadgetskullkeeper80

Answer 7 years ago

 
Yep, that wiring looks OK.  The 6V 1A should be fine if you're only using the one servo.  I would take the 2200uF off the control PCB and replace it with a 47uF or 100uF, then put the 2200uF across the 6V supply, +ve to +6V, -ve to ground.  The capacitor prevents the supply voltage from dropping when the servo draws a short-term high current (spike).

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skullkeeper80AndyGadget

Answer 7 years ago

Ok cool. here is a new pic with cap.

what volt should the 47uf or 100uf be and witch would be best?

thank you for helping

servo controller hookup3.jpg
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AndyGadgetskullkeeper80

Answer 7 years ago

 
Right, you're getting there.  Either 47uF or 100uF would be do the job.  The servo current is away from the controller supply so the value is in no way critical.
Any voltage rating over 5V would be fine.  Common ratings are 10V, 16V, 25V etc.
You could actually run this just off the 6V supply if you added a LDO (low dropout) 5V regulator  to power the controller circuit.  The LDO is a 3 pin device which supplies a steady 5V to the circuit as long as the 6V supply doesn't drop below 5.2V or so (and even if it does, the capacitor on the controller will support the voltage).  A suitable one would be MCP1700-5002E from Farnell (and elsewhere).

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skullkeeper80AndyGadget

Answer 7 years ago

hey i like that idea cheaper then buyin 2 power supplys.

so how do i go about using the LDO?

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AndyGadgetskullkeeper80

Answer 7 years ago


The LDO will have three terminals - Input (to 6V), Gnd (to 0V) and Output (5V to controller board). It's as easy as that.. Who are you using for component supplies - I'll see what they've got that's suitable.

Just re-winding a bit . . . Am I right in thinking that you're using the continuous rotation servo which Steve suggested and you're extending the wires from the pot internal to the servo to a pot located on the arm?
Also, what are the other 3 servos being used fo?

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skullkeeper80AndyGadget

Answer 7 years ago

is the MCP1700-5002E the right ldo i need mamp and all if so ill buy one the only place in my city to get stuff is radio shack and they dont cary the MCP1700-5002E that i can see so i will have to order one online im in tucson arizona. know of a place to get one in US?

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AndyGadgetskullkeeper80

Answer 7 years ago

 
Hi SK, Mouser is pretty big in the US and stock a good range of components
THIS regulator would suit you.  Keep the 2200uF cap on the 6V side, and add a pair of 1uF ones, one on the input, one on the output, very close to the regulator.
They also do a range of 6V power supplies at a couple of amps.  The site won't give me a price on them as I'm in the UK, but there will be something suitable there.

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skullkeeper80AndyGadget

Answer 7 years ago

cool thank you.  my power supply is going to be car cigarette lighter adapter as im installing it on my wheelchair. what do you think of this pic look about right its my way of doing schematics lol

servo power board.jpg
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AndyGadgetskullkeeper80

Answer 7 years ago

 
That looks good to me #;¬)
Don't forget the 100uF or 47uF on the controller board where the 2200uF used to go.  Also make sure the servo power rails aren't going along a single strip of perforated stripboard.  No need to go OTT with it, but beef up the track with a bit of tinned copper wire if that's the case.
Good luck with the build, and report back!

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skullkeeper80AndyGadget

Answer 7 years ago

sorry what do you mean by make sure the servo power rails aren't going along a single strip of perforated stripboard

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AndyGadgetskullkeeper80

Answer 7 years ago

 
What I meant was that you want to keep the resistance path of the servo power rails low. Stripboard on its own is fine for signal level currents, but if the servos are going to be pulling current spikes of a couple of amps then the resistance of the thickness of copper going past the stripboard holes will introduce some voltage drop - Possibly negligible, but in a case like this I'd always solder a piece of tinned copper wire along the length of the power tracks to thicken them up.   

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skullkeeper80AndyGadget

Answer 7 years ago

Oh ok thats what i thought you meant.

you may laugh but when i make my circuit boards i use

1. prototype circuit boards
2. copper foil strips its 1/4" wide copper on one side sticky adhesive on the other side.. just pill off back stick to board if need to add solder every few holes for better stick. works great and easy heres an idea how it looks.

4410.jpgservo power board front back.jpg
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skullkeeper80AndyGadget

Answer 7 years ago

well i don't have a supplier i just look around the web for cheap usually as long as it works. always open for help pointing out the right product.

yes im going to be using what steve suggested , extending pot to arm.

the other 3 servos is for the rest of the joints. theres 3 joints shoulder,elbow,wrist and 1 to turn the wrist.

heres a pic of kinda how it will be just to give you an idea.

and a pic with LDO...everything look right or anything need changed

do i still need cap on 6v side? i think i have a 2200uF i can put and leave the 2200uf on the circuit.

servo controller hookup w LDO.jpgrobot arm ideaexplained.jpg
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steveastrouk

7 years ago

HEY SKULLKEEPER !

You really are making great progress with this thing. Well Done !

Steve

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skullkeeper80steveastrouk

Answer 7 years ago

Thank You Steve you have been a big help to me iv learned so much.

I'm starting to build the arm soon i finished my acer netbook to tablet mod its running smooth looks pretty cool to weighs about 2 lbs thats a full pound less for the arm to lift.

you pros here are great thank you all for helping couldn't do it without you guys.