GTB Speed Spectrum ESC
04-08-2007, 09:55 AM
#16
Tech Rookie
What exactly is the advantage then? "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 and along the lines of a bogus infomercial.
Like I said I have always liked Novak products, but this is insulting and along the lines of a bogus infomercial.
04-08-2007, 10:35 AM
#17
Dude...
You're reading WAY too much into it. That can be dangerous if you don't understand what you're reading.
"RF" is supposed to mean "Radio Frequency", which means little or nothing..."RFI" is "Radio Frequency Interference" which in this case means only slightly more.
All halfway sophisticated electronic devices will *make* "RF" (internally...that's now electronics work)...they don't all *emit* "RF", at least in a meaningful amount or at a frequency that will cause the "I" or "Interference" with other devices.
The conflict/issue they're referring to is internal to your system, not emitted to other systems. If you read what they said on their web page, it said that if they ran the drivers at too high of a frequency, it would cause interference (internally) with the receiver at 27, 40 or 75Mhz.
Since the DSM/Spektrum systems run at 2.4Ghz (2400Mhz?), they can drive them at a higher frequency and achieve some additional efficiencies...waste less energy to heat.
They don't EMIT (or cause "RFI"). Either model.
They're not promising the moon, they just say they made it a little better because they could.
From their page:
"While users should not expect a huge difference in feel or driving style, they will notice improved motor operation and lower ESC operating temperatures."
It costs about the same, I have Spektrum and I'm looking for another ESC (with LiPo cutoff)...why isn't it a good deal?
You're reading WAY too much into it. That can be dangerous if you don't understand what you're reading.
"RF" is supposed to mean "Radio Frequency", which means little or nothing..."RFI" is "Radio Frequency Interference" which in this case means only slightly more.
All halfway sophisticated electronic devices will *make* "RF" (internally...that's now electronics work)...they don't all *emit* "RF", at least in a meaningful amount or at a frequency that will cause the "I" or "Interference" with other devices.
The conflict/issue they're referring to is internal to your system, not emitted to other systems. If you read what they said on their web page, it said that if they ran the drivers at too high of a frequency, it would cause interference (internally) with the receiver at 27, 40 or 75Mhz.
Since the DSM/Spektrum systems run at 2.4Ghz (2400Mhz?), they can drive them at a higher frequency and achieve some additional efficiencies...waste less energy to heat.
They don't EMIT (or cause "RFI"). Either model.
They're not promising the moon, they just say they made it a little better because they could.
From their page:
"While users should not expect a huge difference in feel or driving style, they will notice improved motor operation and lower ESC operating temperatures."
It costs about the same, I have Spektrum and I'm looking for another ESC (with LiPo cutoff)...why isn't it a good deal?
Last edited by Turbo Joe; 04-08-2007 at 10:50 AM.
04-08-2007, 10:44 AM
#18
Factoid, you have been a busy guy this AM!
As I responded on the Hobby Talk forums, where you posted these same comments, I have forwarded your posts to Bob and Adnan Khan (Novak's Senior Design Manager.)
Since it is Sunday--Easter Sunday--here in CA, I expect a response to your assertions sometime tomorrow.
As I responded on the Hobby Talk forums, where you posted these same comments, I have forwarded your posts to Bob and Adnan Khan (Novak's Senior Design Manager.)
Since it is Sunday--Easter Sunday--here in CA, I expect a response to your assertions sometime tomorrow.
Originally Posted by factoid
What exactly is the advantage then? "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 and along the lines of a bogus infomercial.
Like I said I have always liked Novak products, but this is insulting and along the lines of a bogus infomercial.
04-08-2007, 08:26 PM
#19
Tech Rookie
What can I say? Struck a nerve.
Turbo - with all due respect I know exactly what I am reading and what it means in real engineering technical terms. I understand conducted and radiated emissions extremely well and have been thru CE testing many times with high speed switching fet circuits.
The signal between the receiver and the esc is a simple 3v pulse using spectrum or crystals. If the noise is washing out the 3v pulse internally, neither would work. If it is really internal they will have more problems than just radio signal. Hi speed fets passing this kind of current do not take kindly to noise in the circuit. Induce on a high side fet or loose control of a gate for even an instant and the smoke comes out. Hard to convince an engineer that noise is a good thing or that it cannot be controlled
I agree it is probably a fine product and Novak has been a fine company for many years. However, thus far I have to go with Penn and Teller on this one.
Turbo - with all due respect I know exactly what I am reading and what it means in real engineering technical terms. I understand conducted and radiated emissions extremely well and have been thru CE testing many times with high speed switching fet circuits.
The signal between the receiver and the esc is a simple 3v pulse using spectrum or crystals. If the noise is washing out the 3v pulse internally, neither would work. If it is really internal they will have more problems than just radio signal. Hi speed fets passing this kind of current do not take kindly to noise in the circuit. Induce on a high side fet or loose control of a gate for even an instant and the smoke comes out. Hard to convince an engineer that noise is a good thing or that it cannot be controlled
I agree it is probably a fine product and Novak has been a fine company for many years. However, thus far I have to go with Penn and Teller on this one.
04-08-2007, 08:42 PM
#20
Funny...if you know so much about this stuff and you're such an authority on it, why don't you 1) Just build your own ESC or...2) Wait for an answer from the guy who designed it?
If you don't want to hear what he has to say on the subject, then I would submit that you're not as smart as you think you are about it and that you're more interested in hearing yourself "talk" than learning something.
If you don't want to hear what he has to say on the subject, then I would submit that you're not as smart as you think you are about it and that you're more interested in hearing yourself "talk" than learning something.
04-08-2007, 09:07 PM
#21
Tech Apprentice
Originally Posted by Turbo Joe
Funny...if you know so much about this stuff and you're such an authority on it, why don't you 1) Just build your own ESC or...2) Wait for an answer from the guy who designed it?
If you don't want to hear what he has to say on the subject, then I would submit that you're not as smart as you think you are about it and that you're more interested in hearing yourself "talk" than learning something.
If you don't want to hear what he has to say on the subject, then I would submit that you're not as smart as you think you are about it and that you're more interested in hearing yourself "talk" than learning something.
Yes this is my first post, I was reffered over here from RCU, but I am no noob to RC.
04-08-2007, 09:17 PM
#22
It just seems reasonable to wait for an explanation from the guy who designed it before throwing the "BS flag".
Bob and the rest of the Novak guys I've met have always been willing to help out and/or share info when asked without blowing smoke. They're always out at the local enduros beating the crap out of their stuff AND lending out stuff for others to beat on.
They build it and they actually race their stuff every week. If they offer to explain what's new and different about it...then I think only an ignorant tool would turn down the info...or keep ranting about it being BS in the meantime.
BTW -- I just ordered mine from Tower, so don't start about me having some "hook-up" or special "homey" deal.
Bob and the rest of the Novak guys I've met have always been willing to help out and/or share info when asked without blowing smoke. They're always out at the local enduros beating the crap out of their stuff AND lending out stuff for others to beat on.
They build it and they actually race their stuff every week. If they offer to explain what's new and different about it...then I think only an ignorant tool would turn down the info...or keep ranting about it being BS in the meantime.
BTW -- I just ordered mine from Tower, so don't start about me having some "hook-up" or special "homey" deal.
Originally Posted by DeltaForce
A little testy after someone questions the almighty Novak product? factoid makes valid points. I'm no EE or anything, but if that system doesn't work with crystal radios and receivers, it's inadequate. No attempt at fixing the problem encountered = Spread Spectrum Optimized? Gimme a break.
Yes this is my first post, I was reffered over here from RCU, but I am no noob to RC.
Yes this is my first post, I was reffered over here from RCU, but I am no noob to RC.
04-08-2007, 10:01 PM
#23
Tech Rookie
Did I indicate I was unwilling to wait for an answer or not interested in learning? Take it to a flame session if you like, I will not engage in pointless jabs. I was simply establishing some credibility to show I am not a 12 year old just interested in hearing myself talk.
Besides I already read their desc and I do not expect a response here to be any different. It’s a good story and there is not much more to it than they have already told us. They explained it correctly, I just don’t see the advantage. What I read is that they could not fix the problem, which it appears existed in the original version also (see above post), so it became a sales feature. Just does not sound like the Novak I grew up with and respected for all those years.
I will behave myself, but someone has to play devils advocate and I love a good technical debate. I assure you I am smart enough not to show up to a gun fight with a pocket knife.
Don’t feed me BS and I won’t feed it back.
Besides I already read their desc and I do not expect a response here to be any different. It’s a good story and there is not much more to it than they have already told us. They explained it correctly, I just don’t see the advantage. What I read is that they could not fix the problem, which it appears existed in the original version also (see above post), so it became a sales feature. Just does not sound like the Novak I grew up with and respected for all those years.
I will behave myself, but someone has to play devils advocate and I love a good technical debate. I assure you I am smart enough not to show up to a gun fight with a pocket knife.
Don’t feed me BS and I won’t feed it back.
04-08-2007, 10:13 PM
#24
It sounds like you've already made up your mind that they're full of crap...but hey, that's just how I read your explanation.
You could try to explain your reasoning further, but it doesn't sound like there could be anything else you could add that will change my mind.
You could try to explain your reasoning further, but it doesn't sound like there could be anything else you could add that will change my mind.
04-08-2007, 10:39 PM
#25
Tech Rookie
Not trying to change your mind or tell anyone not to buy it. I am sure it works great when used with a spectrum radio. Honestly the original works works pretty darn good on a crystal radio. I still respect them enough to think they would not sell a poor product. They are not stupid, somebody just seems to think we are.
Man these forums are addicting. Now I remember why I do not get involved. I am done unless there is some real science to argue. Its my own damn fault for letting it bother me to begin with. I only intended to start a discussion not be the center. I might have to kick my own ass.
Man these forums are addicting. Now I remember why I do not get involved. I am done unless there is some real science to argue. Its my own damn fault for letting it bother me to begin with. I only intended to start a discussion not be the center. I might have to kick my own ass.
04-08-2007, 11:40 PM
#26
...and they say subtlety is wasted on the internet...LOL 
You missed the joke. 
I'm really interested to hear what he has to say. I bought it because I needed one, it was only $10 more and it had the LiPo cutoff. If it runs cooler because of the high-frequency stuff...good deal...if it only works as good as my SS+ already does...good deal, too.
I have a Mamba 7700 (got it CHEAP!), but it's pretty "hungry" compared to the Novaks. Fast as hell, though...
You missed the joke. I'm really interested to hear what he has to say. I bought it because I needed one, it was only $10 more and it had the LiPo cutoff. If it runs cooler because of the high-frequency stuff...good deal...if it only works as good as my SS+ already does...good deal, too.
I have a Mamba 7700 (got it CHEAP!), but it's pretty "hungry" compared to the Novaks. Fast as hell, though...
04-09-2007, 07:17 AM
#27
Tech Regular
Wow, you guys are simply amazing.
If you think that there's no advantage then simply don't buy the product. It's really that simple. Some of us actually run enough motor to thermal the speedo and the new speedo's should help this. It's a good thing for everyone that's running the current stuff at the limit and has DSM.
The whole interference thing has been around ever since they introduced speedo's with adjustable drive frequencies. Crank them up too high and you'll get hits. This was not just with the Novak products either...
Crystals are on the way out (analog in a digital world). It's only a matter of time.
If you think that there's no advantage then simply don't buy the product. It's really that simple. Some of us actually run enough motor to thermal the speedo and the new speedo's should help this. It's a good thing for everyone that's running the current stuff at the limit and has DSM.
The whole interference thing has been around ever since they introduced speedo's with adjustable drive frequencies. Crank them up too high and you'll get hits. This was not just with the Novak products either...
Crystals are on the way out (analog in a digital world). It's only a matter of time.
04-09-2007, 10:49 AM
#28
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.
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.
04-09-2007, 11:35 AM
#29
I love when you talk technical.
04-09-2007, 03:58 PM
#30
Thanks Adnan. I'm a ChE not an EE, but I actually followed about 50% of what you said. 
Nevertheless I appreciate the explanation. With my 4.5, it is taxed fairly heavily (more so offroad actually than onroad where I spend more time BRAKING). The ESC definitely gets hot. I understood enough of what you said to confirm that I definitely want the SS version for my next GTB purchase.
Nevertheless I appreciate the explanation. With my 4.5, it is taxed fairly heavily (more so offroad actually than onroad where I spend more time BRAKING). The ESC definitely gets hot. I understood enough of what you said to confirm that I definitely want the SS version for my next GTB purchase.