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Old 07-17-2008, 09:33 AM   #1
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Questions?? servo upgrade?

I tried searching but the word servo brings up a ton of threads that don't look like what I need to know. I'm looking for suggestions on a new servo. I currently have the B4 RTR servo in my B4. I run a CC sidewinder + 5700 combo. I've got a futaba 2pm 2.4Ghz radio. The car can go faster than I can drive for the most part. I race and am trying to get faster. I'm getting to the point where I'm making around the track with minimal crashes. It seems as though my next challenge will be to learn how to pass cars I'm laping.

Back to question at hand! What servo could I get that would improve my lap times and not break the bank. To me that's about $55 or less. Also reliability is key for me. I don't want to be replacing it after one season of normal use. Digital or analog? BB? High torque necessary? Is .20 sec a fast time at 6.0V? I'd probably like to stick to Futaba, but am open minded.
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Old 07-17-2008, 10:20 AM   #2
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The Futaba S9452 would be a good choice, but its around 80 bucks. Its a very quick digital servo that should last you quite a while. You get what pay for especially with servos. Spending a little extra now will save you money later so you're not replacing a cheapie real quick like.
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Old 07-17-2008, 11:01 AM   #3
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Originally Posted by jla8874 View Post
The Futaba S9452 would be a good choice, but its around 80 bucks. Its a very quick digital servo that should last you quite a while. You get what pay for especially with servos. Spending a little extra now will save you money later so you're not replacing a cheapie real quick like.
JLA8874 is right, Buy a good servo once especially if you are really into racing and feel you will be into this for a while. My recommendation is the jr9100s if you can hold off and get one. It will last you for years to come although it isn't cheap @ 114.99.
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Old 07-17-2008, 11:20 AM   #4
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+1 I have a JR 9000t that is 4 years old. I run a 9100s in my 1/10th scale.
the JR 8711 is awesome in my truggy.
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Last edited by badassrevo; 07-18-2008 at 09:20 AM. Reason: oops I meant 9000t
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Old 07-17-2008, 11:24 AM   #5
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+1 I have a JR 9100t that is 4 years old. .
How is that possible ?
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Old 07-17-2008, 02:13 PM   #6
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I personally use a H645MG from Hitec. That is enough for me, but I could go for a faster transit time...

Main things to look for is torque (Over 133 oz-in (at 6.0V) if you're doing offroad), transit time (<0.2sec), and metal gears and dual BB to have it last a long time...

I've always found Hitec servos to be the best value for the buck...

I'm going to experiment with a Hitec HSR5990TG servo that I use in my bot. This thing puts out roughly 333oz-in at 6.0V, but again, transit time is another matter. The shorter the transit time, the more "real-time" your car will feel to your input when steering...
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Old 07-18-2008, 06:14 AM   #7
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Hey buddy, THIS looks like a good deal.
He's down to 70 shipped now and its BRAND NEW.
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Old 07-18-2008, 09:10 AM   #8
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Hmm, I wonder if those are the servos that were built for the Robo-One. It doesn't seems like it, since the thing comes with a fancy case. Also the transit time seems really fast, 0.11, perfect to be used for steering in an RC Car application...

One word of advice, stay away from HS5995. The FETs inside these servos have been known to cause unexplainable failure (with minimal or no load on the shaft)... These were servos created for the Robo-One competitions, and they weren't really made to last...

Oh yeah, BTW, Hobbico CS-170 is the rebadged HS5955TG (which is simlar in torque to the HSR5990TG except it can't be raised to 7.2V). The only difference between a CS-170 and a HS5955TG is that the CS-170 can't be programmed with Hitec's HMI servo programmers (not that you would need to)...
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Old 07-18-2008, 09:47 AM   #9
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raised to 7.2V I guess I may be a little confused on the voltage thing for servo's. I have my car setup as follows. My battery 6 cell 4200 nimh (7.2V I think) is connected to my esc. The esc had a switch on it that shorted out so i cut it off and hard wired the wires together. The esc runs to my receiver and my servo is also connected to my receiver.

Do some of these servos require their own power pack? I read something in one of them that made me wonder about this. Are they all compatible with the way I am hooked up. I liked having a switch at first but had it turn itself off once in a qualifier so now I appreciate the hard wired setup again. Also a lot of the specs on the servos I am looking at are rated at 6.0V. Will I see improved performance over these numbers as I am running 7.2V. Am I seeing this all correctly? Thanks for the suggestions. I'm trying to do my research now and pick one up this winter for next season. Most of my slowness currently lies between the 6 inches of real estate between my ears and the two fixtures that hold my transmiter.
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Old 07-18-2008, 09:55 AM   #10
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Quote:
Originally Posted by squeaks View Post
I tried searching but the word servo brings up a ton of threads that don't look like what I need to know.
Asking such a vague question is going to give you a bevy of opinions, likley not a whole lot different than what you've already seen in other threads on the same topic.
Don't shortside yourself by relying on just a few opinions, but instead get some knowledge by reading what a lot of people have said. Use the seach option and learn something, a lotta something ~ and then when you have a more specific question log back in.
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Old 07-19-2008, 01:23 AM   #11
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hey squeaks, you pose some good questions, let me try to answer them...

On a hitec, the red wire is for the supply and the yellow is for the PWM (pulse width modulation) and the black is gnd/common... I won't go into what PWM is, but just know that it's a mechanism to control the position of the servos...

You would hook up servo packs in a nitro since the nitros can't provide the receiver with a supply through the "red" wire.

In an electric vehicle, the red wire off of the ESC to Receiver connection provides power to the receiver, as well as the servo since the servo's red wire is on the same rail... I believe some ESCs will crank(regulate) the supply (battery) down to either 4.8V or 6.0V and feed that to the receiver.

For robotics, often times, the receiver's power (red) is fed separately with a dedicated power source. Torque is often the most favored attribute of a servo in robotics, and torque is proportional to the supply voltage into a given servo. However, most servos (standard size for hobby use like RCs) are rated up to 6.0V. You can feed it higher voltage, but it won't last as long and you risk blowing out the servo (usually the power FET).

The 5995s have been prone to this problem...

In R/Cs however, it's not just about torque. Although in off-road, you will need quite a bit of torque. You also need a fast transit speed since that will dictate how responsive your car will feel...

To answer your question, I have hooked up a 6-cell Sub C (nominal 7.2 but it can be as high as 9.0V after fully charged with no load) to my H645MG which have max operating voltage of 6.0V.

The servo felt like it was on steroids (more torque, faster transit time), but it's quite dangerous and my servos heated up quite rapidly...

I wouldn't recommend it. Notice how most "radio" packs are 6.0V or less, consisting of a 5-cell 2/3AA size...
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Old 07-21-2008, 06:49 AM   #12
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dear rocket,

It was meant to be a vague question. After 5 years of college my vocabulary is still a little shy apparently. I have no idea what a bevy is comparative to( ton, metric ton, shit ton). In this thread I have found a plethora of the information I was looking for. I found no other threads looking for a general outlook on servos(not to say that one doesn't exist, just couldn't find it). I did not want a X vs Y comparison. I wanted to know what was available on the market. Now I know enough of something to make a semi educated decision imo.

Dear Tom,

Thanks! I knew about the Nitro thing, but was just unsure if some hardcore people were doing the extra pack on electric as well. Thought maybe something had changed since I first got into this a decade ago. I've recently started racing and am looking for all the competitive edge I can get a hold of. Is there a good way to tell what the voltage coming to my receiver is? aside from busting out my multimeter and checking while the car is hooked up. I have a CC Sidewinder esc btw.
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Old 07-21-2008, 06:52 AM   #13
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your sidewinder puts out 5 volts
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Old 07-21-2008, 12:58 PM   #14
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having come to electric from 8th nitro, servo strenth has always been a worry of mine. i started off with the servo from my 8th buggy a Ace/associated 1015 it is half the price of most servos in the uk, just as quick and 3 times as strong, i have since moved up to a super quick ko one but for the money you cannot beat the ace, mine did a full season of 8th then 2 1/2 seasons of 10th and i was racing nearly every weekend as well so well worth a look
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