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Old 04-11-2007, 06:01 PM   #46
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I guess you can take any answer and put a spin on it if you want to. Twists and turns are always fun.

Why would we want to come on here and talk with you if you're going to "twist" everything we say. Take it easy man, we're all friends here.

The ESC operates cooler is all, so now, it can be used by more people for more applications. Most if no ALL of the early problems with thermal stem completely from overheated rotors. I know, because I'm the guy that does the warranty inspection on systems. Virtually all of the systems sent in were accompanied by a Motor that had a "toasted" rotor.

I know I know, go ahead twist it around into what ever you want.

The Simple fact of the matter is, the spread spectrum optimized ESC works slightly better under heavier loads and hot conditions. That does not mean in any way shape or form that the regular GTB is bad, or won't work in the same conditions. JUST that the Spread Spectrum Optimized will be better. That is all. Come out to any race and I'll prove it to you. The reedy race this year will have racers using BOTH the Spread Spectrum Optimized and the Regular GTBs Side By SIde on the same track with the same motors under the same conditions. WIll the Spread Spectrum users have an advantage, mostly likely a small one yes, but in racing sometimes thats all it takes.

Adnan's going on vacation for a week or two, if you'd like, you can email me and I'll happily forward your emails to him directly.
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Old 04-11-2007, 06:04 PM   #47
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Oh, Yes, 2 Power Caps is an improvment in performance... Oh wait I better be careful, some might take that as the single cap being bad, or not good enough, or what ever........

Syndrome, No unfortunately that is not the case... I wish it was...

To our count these same posts are on 4 different forums around the wonderful world of the internet.

Thanks buddy.
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Old 04-12-2007, 02:18 PM   #48
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Quote:
Originally Posted by factoid
Thank you MR. Khan for taking the time to explain this in detail. It is text book engineering and exactly what the press released claims with more detail and maybe a few unintended admissions. I agree with almost all of it and I have to say you made my case for me nicely.

I can accept that you had to increase switching speed to the point that there are problems with crystal radios because the unit cannot handle the heavy loads and overheats even with a heat sink and a fan. I guess for marketing purposes that had to be shortened to ‘Spectrum Optimized’. Otherwise it really does not have that ‘I gotta have it’ ring to it.

If it truly makes the unit considerably better, then perhaps the trade off is worth it. If it simply makes it work then I still say it is a Spectrum Bandaid and a marketing spin.

Some may argue that the GTB did not have thermal problems to begin with. I suggest you search the word ‘Thermal’ in the 60 pages on Rctech in the electric onroad section ‘New Novak Brushless system’. It is not like it is a secret that it has been an issue.

I think you should check out the competition a little closer. Many products are switching much faster than you mention. I believe the Castle unit switches in less than 100ns or 10 times faster and so does the Quark unit. I see Tekin does not even have a heatsink on their new unit so they must also be switching pretty fast to pull that off. Somehow they all controlled the RF and do not require the use of 2.4Ghz radio.

Now that it has been explained (admitted) that RF and heat could not be controlled at the same time for some reason in this circuit I will leave it be. At least that is better than a creative marketing angle to cover up a design problem. However for those in the know I have to say you have lost your position as the technology leader and then tried to tell us it was a good thing and we should be excited about it.
Dear Factoid,
I would like to correct a statement that you made in this post. There is nobody in this industry that is switching as fast as you say they are. 100nsec switching speed in a mosfet speed control will drive every non spectrum radio manufactured crazy. The Castle Speed control switches at about 1300 nsec (measured). That's a little higher than 100 nsec. This is about as fast as anybody can switch their speed controls and work with all the AM and FM radios that are in use today. Tekin found this out at one of the last big races when their vender manufactured their new speed controls with the wrong gate resistors and the speed control switched the mosfet’s too fast. They were unusable with standard FM Radios.
Spread Spectrum radios have finally given us manufacturers the ability to switch our speed controls faster to make the speed controls a little bit more efficient. Remember we are in the racing business and any time we can offer a product that gives a little bit of an edge we will manufacture it and sell it to the public. Call it what you may, I call it good marketing.
By the way, another car on the track that has a non Spread Spectrum receiver in it will not be affected by these higher switching speed controllers.
Also everybody needs to remember that ALL radios are crystal controlled even the Spread Spectrum systems.
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Old 04-13-2007, 07:55 AM   #49
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I used to run an old Futaba 2PH radio, 75MHz AM, with a GTB 4.5 system on a carbon fiber chassis. It took some detective work to fix all the issues with this ancient radio and I had to add a receiver cap and use dry cells in the transmitter, put my receiver on the front of the top deck and twist my battery wires together... but the reason I finally upgraded my radio was because I got interference from BRUSHED motors in close side-by-side racing and took people out even in the straightaway.

My only regret with DSM is no more excuses if I accidently take someone out.
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Old 04-14-2007, 08:05 PM   #50
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Well, I finally got to test the 1711, I have it in my Darkside I Force pan car, with 4 cells, about 40-41 ounce weight. I was able to test it in the street and driveway. Compared to the last time I had a 13.5 in the car with the old Super Sport esc, with the same gearing, I'm impressed!! The motor temp was 98 F and the esc was 85 F all this after 4 minutes of full throttle and stop and go, partial throttle, etc. The best part is the speed appears to be better. I'll know for sure tomorrow if the weather holds. I like it, Good Job Novak!!
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Old 04-14-2007, 08:09 PM   #51
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Quote:
Originally Posted by swopemike
I used to run an old Futaba 2PH radio, 75MHz AM, with a GTB 4.5 system on a carbon fiber chassis. It took some detective work to fix all the issues with this ancient radio and I had to add a receiver cap and use dry cells in the transmitter, put my receiver on the front of the top deck and twist my battery wires together... but the reason I finally upgraded my radio was because I got interference from BRUSHED motors in close side-by-side racing and took people out even in the straightaway.

My only regret with DSM is no more excuses if I accidently take someone out.
I didn't know it was the radio causing those problems!!
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Old 04-16-2007, 05:46 PM   #52
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I was able to give the 1711 a good testing yesterday, 2 heats and the b main, 5 minutes each. I used it on my I Force pan car with a 36/112, 3.11:1 gearing, with 4 cells on a 13,5 motor. I temped the motor and esc immediately after each race, the highest motor temp was 110 F and the esc never exceeded 98 F. The air temp was about 65 F ant the asphalt track temp was about 80 F at the hottest point of the day. I was able to pull the Tc's on the topend and out of the corners, I just lost too much time in the infield section of really tight corners. I am going to work on some things to help the steering. Overall I am thoroughly pleased with the 1711. the car was faster with it that the other esc I was using. (marketing ploy or not, it works!!!!!) Thanks Novak
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Old 04-20-2007, 12:57 PM   #53
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Stupid question. Does the 1711 come with a sensor wire in the box? Otherwise I need to buy one for the vortex.
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Old 04-20-2007, 01:41 PM   #54
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Sorry, the 1711 does not come with a double ended sensor harness for the motor in the box.

Being as that all our motors come equiped with them we didn't see a need to have them included but that is something we are definately re-thinking.

Quote:
Originally Posted by secretsg
Stupid question. Does the 1711 come with a sensor wire in the box? Otherwise I need to buy one for the vortex.
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Old 04-20-2007, 05:32 PM   #55
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Hey guys, I just got the GTB with 4.5. The guys at my local track said that the 4.5 is going to be way to hot for my 4wd off-road car. Anyway to slow it down? Could I just setup my transmitter so I don't get 100 percent full throttle. They said a 6.5 will be more suitable, but I just don't wanna fork out the money for that just yet, and I don't want to run one of my regular mod motors. Is there anyway to make this 4.5 work and slow it down LOL. Is there any adjustment via esc I can change?
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Old 04-20-2007, 05:42 PM   #56
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Silence,

Your best bet would be to turn the EPA down from 100 after you set the ESC up like you mentioned.

You will probably want to add some negative throttle exponential to your radio as well to help smooth out the bottom end as well.
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Old 04-20-2007, 08:11 PM   #57
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lower voltage battery packs.
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Old 04-20-2007, 08:24 PM   #58
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hi novaks

how do we get our old GTB upgrade to the new GTB??

is there a extra fee? how much?

thanks
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Old 04-20-2007, 08:31 PM   #59
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Quote:
Originally Posted by Charlie
Oh, Yes, 2 Power Caps is an improvment in performance... Oh wait I better be careful, some might take that as the single cap being bad, or not good enough, or what ever.........
charlie, i have seen nexus' 2 power cap.

would you make one as an option part so we can buy it.?

thanks
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Old 04-20-2007, 09:55 PM   #60
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So, the new GTB is simply only a high frequency switching version of the old GTB. Which is a FAR CRY from what is mean by Spread Spectrum (Such as Spread Spectrum in CDMA mobile phone system). Maybe Novak means it is the RFI generated is Spread Spectrum

From Novak web site:

"Please note, the #1711 GTB Spread Spectrum Brushless/Brush ESC and the #1715 GTB 4-Cell Spread Spectrum Brushless/Brush ESC are for use only with Spread Spectrum radio systems (2.4GHz radio systems)."

So, does it means that the new GTB cannot be used with traditional AM/FM crystal based radio ? How many manufacturer actually product Spread Spectrum (2.4G) radio system ?

Novak in the past produce very high quality and robust ESC, hope they continue this tradition. We want high quality product, not marketing hype.

Quote:
Originally Posted by NovakTwo
Over the years, the Mosfets used in Novak's ESCs have steadily gotten better and now we have reached a point of diminishing returns as far as the Rds On of the Mosfet is concerned. The GTB uses Mosfets that have a Rds On of 1.2 milli ohm. The PCB and wires have much higher resistance than the Mosfets, so why does the ESC still get hot? That is because most of the heat is caused by the switching losses and not the Rds loss.

In an ideal situation, we would like to see zero switching rise and fall times. Fast rise and fall times cause large current spikes and produce lots of radio frequency interference. In a power supply or piece of industrial equipment, typically the manufacturer encloses the power section in a steel box and uses a large ferrite core to reduce the RFI noise. We don’t have that option!

In the GTB design we have had to slow the rise and fall time significantly so that it would work with ALL the radios out in the field (slowing the switching rate brings the noise floor down by 30-35 dbm). Compared to other high performance ESCs out in the field, the GTB has the fastest switching rate as we use 6 layer power PCBs with lots of ground plane and high frequency capacitors to de-couple noise.

Slowing down the switching rate causes more heating because the Mosfets are in the linear region of operation for longer periods and that accounts for most of the heating in the ESC. Also as you slow the switching rate, the pulse width driving the Mosfets starts to look like a trapezoidal wave form instead of a square wave and that causes the trigger control resolution to go down.

The last issue is that the dead time between the electronic commutation required goes up as we have to wait for one bank of Mosfet to turn off before we can turn on the next bank. In our Brushless ESCs we have six commutation steps per revolution, so any improvement in dead time reduction and switching efficiency can be significant.

The Spectrum optimized GTB uses a very fast Mosfet drive circuit switching speed (in the order of 1uS or less) and that will translate into significant improvement in efficiency under high loads and much smoother throttle response. We at Novak are committed to bringing the best possible racing Brushless system out to market and we are continually pushing the envelope of technology. Spread Spectrum allows us to improve the system performance without affecting the radio performance.

One last note on the fast switching ESC: it does not interfere with the radios outside of the car, so you will not be causing interference to the car next to yours whose user has the traditional crystal radio.
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