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Does any one have any information about the GTB Novak Spectrum Speedo listed on tower hobbies, (and on other sites for that matter)? Like is it a whole system, motor and all? Or is it a special speedo for people with a spectrum radio? What, if any thing can any one tell me about this. I was thinking about ordering one from tower, because i thought it was the latest and greatest, but I don't really know that, because I don't know any thing about it!!!! Any info would be appreciated... :wave:
 

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Lance you want the 4 cell model. I seen the new ss speedo last weekend it looks like half a gtb. Its not on the novak site yet.
 

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It is for people who have the Spektrum type radio don't think there is any benefit to you if you do not have the Spektrum type radio. I was thinking of getting one (I have a Spektrum), but it is not yet leagal for racing with any of the recognized racing organizations and it could be a while IF they are approved as it would give racers with a Spektrum radio and adavantage so I bought the regular GTB. Ralf
 

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I spoke with Novak about 2 weeks ago and the only difference is that the speedo operates at a higher frequency which allows for the speedo to run cooler. The higher drive frequency will cause glitching in the older FM and AM systems.
 

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Will it mess up other cars on the track using crystals?

Regardless I am not convinced that generating RF is a good thing or required to achieve performance. Yes switching fast can reduce heat, but good fets switch plenty fast without generating RF if done right. It is not as simple as fast=RF. It is a combination of things that cause it and it can always be filtered out with a little money and effort.

Novak should be embarrassed that they could not keep their unit from thermal shutdown without generating so much RF that a crystal radio does not work well, and then telling us that this is a neat new feature.

Sorry, but we put up with so much bull in marketing and I am simply disappointed and insulted by this promo angle. I have always liked Novak products but this is not good engineering. Bugs me enough I did my first posts on several forums.
 

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Factoid again! Exact same post as you put in the General section, at least you know how to cut and paste. Again I SAY "2 POSTS" new member, did you sign up to bash NOVAK? Actually I haven't heard of that many thermalling, and when they do NOVAK's excellent customer service takes care of it promptly, unlike someone else I have had to deal with (but do so NO longer, ever tried to get a hold of anyone at Associated (Thunder Tiger)). Sound like to me thay are again leading the way in the new technology for us Oval racers, I see more and more people going to Spektrum radios so they are going with the flow and not just sitting on the bank waiting to see what happens like the other manufacturers. My .02 Ralf
 

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I have forwarded this post to Bob Novak for response and I will post his comments here, when available.

factoid said:
Will it mess up other cars on the track using crystals?

Regardless I am not convinced that generating RF is a good thing or required to achieve performance. Yes switching fast can reduce heat, but good fets switch plenty fast without generating RF if done right. It is not as simple as fast=RF. It is a combination of things that cause it and it can always be filtered out with a little money and effort.

Novak should be embarrassed that they could not keep their unit from thermal shutdown without generating so much RF that a crystal radio does not work well, and then telling us that this is a neat new feature.

Sorry, but we put up with so much bull in marketing and I am simply disappointed and insulted by this promo angle. I have always liked Novak products but this is not good engineering. Bugs me enough I did my first posts on several forums.
 

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Been reading for years, finally bugged enough by something to get involved. We all had to do our first post somewhere and had a reason that motivated us. Found this thread second and it had more viewers.

I am not bashing, I am stating the fact that this is a design problem that marketing is claiming as a sales feature. I love brushless, but do not like seeing one of the most respected companies in the industry market like a bogus claims infomercial.

What exactly is the advantage? "Does not provide any noticeable performance difference", claimed in their own press release. "Does make the esc slightly cooler", which would not matter if it is was not problem to begin with. Why accept a negative like RF noise unless there is an advantage to offset it? Show me a good design engineer that will say anything different. Prior to this press release Spectrum Optimized would have meant broken to most of us and now it is a good thing?

Like I said I have always liked Novak products, but this is insulting. Blind loyalty just makes you one of the sheep they are counting on. If you have not heard of any thermal issues with the Orange and Blue systems you live in a box with no windows. May not be a major issue for everyone, but I have seen it, done it and read about it hundreds of times. Why else would they corner themselves into one radio type unless there is some performance advantage for the user, unless they had to make it work.

Looking forward to hearing a solid arguement from a experienced designer such as Mr. Novak. Show me the facts and convince me.
 

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Adnan Khan (Novak Electronics) GTB Spread Spectrum

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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Factoid says

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.
 

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All the thermaling problems I was close enough to that I could ask questions were ALL abuse problems due to improper gearing, again we tend to abuse our equipment in RC.... Ralf
 

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If Tekin ever actually releases any of the 23 products that they say are "coming soon", we will all be able to judge Tekin's new technological superiority.

After all, Tekin only recently admitted that a capacitor is necessary with high performance speed controls. ;)

Hmm...."factoid"?

factoid said:
Factoid says

...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....
 

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All the thermaling problems I was close enough to that I could ask questions were ALL abuse problems due to improper gearing, again we tend to abuse our equipment in RC.... Ralf
This is why Charlie from NOVAK suggested we OVAL guys don't try to use the Rock Crawler 18.5 motor w/ the LIPOs as a STOCK 4 cell replacement. Having no heat protection in that motor..he's afraid knowing how us OVAL guys PUSH things really hard...it would probably have a overheating issue.

Waiting on something like a 21.5 now...cause the 17.5 was still a couple TICKS too fast.
 

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Well it looks like Novak answered Factoids latest post on RC Tech... heres a copy...

"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.
Bob Novak"
 
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