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Old 09-20-2003, 10:06 PM   #1
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Default servos @ 4.8v and 6.0v (JR DS8201)

i have a JR DS8201 servo that came with my JR heli radio. i want to use this in my nitro car. here are the specs of the servo...

http://www.rotor.com.sg/jrservo.htm

it says: 4.0 kg. cm. torque, .19 sec speed

do you guys know if this will work at 6.0v? the specs didnt say whether its at 4.8v or 6.0v. i used the servo with my 4-cell 4.8v heli pack. i want to be sure if it will work at 6.0v because i will be using a 5-cell 6.0v pack in my nitro car. i dont want to risk damaging the servo. ive seen some heli/plane servos that are rated at 4.8v only and im not sure if the DS8201 is one of them.

if you guys have any info on this servo if it will work at 6.0v, pls post. thanks in advance
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Old 09-21-2003, 03:32 AM   #2
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I dont know this particular servo, but I've never heard about servos that couldnt handle 6 volt. I believe they are designed for use with 4 1,5 volts alkalines. Hope that helps. Otherwise, try to send JR an e-mail.
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Old 09-21-2003, 07:46 PM   #3
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marvi,

It's not the the servo is only rated for 4.8V. That was the voltage used to get those specs. At 6.0V the servo will be faster and have more torque. Some manufactures give both specs (4.8V and 6.0V) . When comparing servos you need to make sure that you're comparing the same input voltage, otherwise two similar servos will be very different due to the increased voltage. You shouldn't have to worry about using a 5 cell pack with your servo.
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Old 09-22-2003, 12:28 AM   #4
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futaba has 4.8v only servos ...

http://www2.towerhobbies.com/cgi-bin...?&I=LXADX7&P=0

ive searched some heli & plane sites about this servo but i still cant find any info if i can use the JR DS8201 at 6.0v. the closest answer i got was when i came about another bb - it was about a JR 811 digital servo (a lower model of the 8201, i think) and the guy also wasnt sure if it can handle 6.0v. another guy answered that it can handle 6.0v, but there are no sites or links where i can verify that.

anyway, i think ill just email JR. their site also doesnt have info if the 8201 can handle 6.0v
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Old 09-22-2003, 08:30 AM   #5
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Your servo's spec seems a little on the low side to put into a Nitro car. Why not upgrade it for a Hitec 645 or better still, a Hitec 5925 Digital servo - this servo really kick's butt and is far cheaper than many other 'big brand' servos despite having a better spec.

With a Nitro car you'll need good, positive steering AND a powerful throttle servo for good brakes. Don't mess about with weak servos, it's a false economy. The servo you mentioned is good for light duty work only. If money is tight, then seriously consider saving up - once you've got them, you've got them for good.

Hope this helps
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Old 09-22-2003, 08:50 PM   #6
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well, i just have this servo lying around and i was gonna use it for nitro bashing only. youre right though, the specs seem to be the same as a standard servo. i was wondering why JR would have a digital fet servo with low end specs maybe they designed this exclusively for planes. as of now, im still afraid to plug it in a 5-cell 6.0v pack so ill just mount this on my 4-cell 1/12 to be safe
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Old 09-22-2003, 10:20 PM   #7
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marvi,

I have seen some digital servos that can not handle over 6V. They were damaged when connected to a freshly chargerd 5 cell NiMH pack. Interestingly the same servo ran great with 4 alkaline cells. After speaking with Hitec tech's it turns out that this can happen with some digital servo/reciever combos. If the reciever does not have a regulator then the voltage to the servo can excede 6.0V and possibly damage the servo. All three examples were in Futaba RX's with one Futaba sevo and two Hitec servos.

Your best bet will be to stick with a servo that gives you specs at 6V as this is an indication that it can handle that voltage.
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Old 09-23-2003, 02:16 AM   #8
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Buddatech:

This all sounds familiar!! I heard from various 'reliable' sources that 'Hitec servos can blow if used on 6v'. The one thing they all had in common was that they wanted to sell me Futaba gear

My Hitec servos - 615's, 645's and my digital 5925's have performed flawlessley on 6 vollts in my MBX4 and other models.

So relax - you can buy performance at lower than Futaba/KO/Sanwa prices
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Old 09-23-2003, 03:05 AM   #9
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A quick chat with the tech guys at Hitech confirms that it is no problem using 6 volts on the servos I mentioned. One more thing - 6v is 6v, so why would it make a difference using Nimh if 4 Alkalines produce the same voltage? I smell a rat

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Old 09-23-2003, 04:00 AM   #10
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Quote:
Originally posted by BuddhaTech
marvi,
...Your best bet will be to stick with a servo that gives you specs at 6V as this is an indication that it can handle that voltage.
thanks for the advice i dont want to risk damaging this servo, its a bit expensive since i plan to use it on my 4-cell 1/12, its safe to say that it will be receiving about 4.8v, right?
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Old 09-23-2003, 08:11 PM   #11
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Horatio,

A cell during charge can reach 1.6V. Once removed from the charger the voltage will begin to fall. It will remain well above the nominal 1.2V rating for a little while or until a load is placed on the cell. If you check the standing voltage of a freshly charged 5 cell (NiCd or NiMh) you can get nearly 7V. The voltage will come down soon to at or just below 6V but in the meantime you could damage the servo or receiver. This is most common when you cheat and throw a higher curent at the pack so you can run right away. A brand new alkaline cell will almost never have more than 1.55 V/cell. No rat's here...

In fact Futaba and Airtronics have receivers that can not handle more than 6V (like the rec. that comes with the MX-3). The instructions (who reads those?) even warn you to not use more than 6V.

Marvi,

You shouldn't have any problems in you 1/12 with that servo.
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Last edited by BuddhaTech; 09-23-2003 at 08:26 PM.
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Old 09-24-2003, 03:35 AM   #12
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Buddatech: Oh right, I see. But doesn't that freshly charged pack that's showing 7v at rest zip down to 6v as soon as a load is applied?

One reason why I may never have experienced this phenomena is because I don't use any of my servos with Futaba receivers; I use Hitec dual filters and LRP micro receivers on 40FM. It makes you think thought doesn't it?

Cheers
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Old 09-24-2003, 11:32 AM   #13
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Default servos @ 4.8v and 6.0v (JR DS8201)

Guys;

Be advised that some manufacturers will NOT warranty a 4.8v Aircraft Servo, if it have been found to be used @6v or in a Car/Truck (JR being one of them).
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