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-   -   Viper RC - (https://www.rctech.net/forum/radio-electronics/455152-viper-rc.html)

nikos2002 08-23-2013 07:30 AM

bob- hold on tight!! we have actually seen team drivers run Punch as low as 20 to keep the wheelspin down.

boostem - glad you figured it out - sometimes the neutral signal is not clear from the radio. but you got it going.

Neo 13 update - Lee Martin uses the VTX8 and new VF8 2100kv motor to lead 1st round of eBuggy practice. He was 4th in round 2, but his 1st round run was still good enough for 2nd fastest so far. Fingers crossed!!!!!

Motorman007 08-23-2013 07:37 AM


Originally Posted by nikos2002 (Post 12476276)

Neo 13 update - Lee Martin uses the VTX8 and new VF8 2100kv motor to lead 1st round of eBuggy practice. Fingers crossed!!!!!

So is the 2100kv Ideal for buggy? I was thinking Truck.

Can you give me some insight on when to use what motor please sir?

VF8.19 (1900kv)

In what buggy or truck?
On what type of track?


VF8.21 (2100kv)

In what buggy or truck?
On what type of track?

VF8.27 (2700kv)

In what buggy or truck?
On what type of track?

Thank you sir

Bob Barry 08-23-2013 07:48 AM


Originally Posted by nikos2002 (Post 12476276)
bob- hold on tight!! we have actually seen team drivers run Punch as low as 20 to keep the wheelspin down.

Neo 13 update - Lee Martin uses the VTX8 and new VF8 2100kv motor to lead 1st round of eBuggy practice. He was 4th in round 2, but his 1st round run was still good enough for 2nd fastest so far. Fingers crossed!!!!!

Yup, last time I ran my VTX8 I was at 55% punch and 16,000 mHz PWM to cut back on wheel spin.

So Nick,

Lee, Neo, 2100 :sneaky:

Cain 08-23-2013 09:57 AM

I think what you may to look at for truck versus buggy is can length. That is primarily what all the other guys have as the difference.

But, to be honest, in a pinch I had to throw in a buggy motor into a truggy once, and to be honest it worked just fine.

Ivegotklas 08-23-2013 10:06 AM


Originally Posted by Barge (Post 12473333)
Are there any write-ups to detail how this actually affects the system in a positive way? As an enginerd it's nice to read about the why sometimes.

http://en.wikipedia.org/wiki/Low-pass_filter

From an electrical stand point the cap really acts as a low pass filter. Kinda like on a speaker crossover. The cross over send all the high pitch noise to the tweeter and the low pitch to the woofer. In this case the capacitor acts like a speaker cross over with no tweeter. The high frequencies produced by the ESC during acceleration and breaking get filtered by the capacitor. The low frequencies (i.e. DC voltage) come from the battery.

So how in return do you get better run time and acceleration. The key here is the effect of the cap on the battery. Lipo's are DC, under a PWN driven motor (ESC) the power required to drive the system has lots of transients (i.e. high frequency noise). Batteries have a hard time with producing that power. With out a capacitor the battery would heat up and have high voltage drop accross it. Thus lower run time and less acceleration. The impedence (i.e. resistance and reactance) of a capacitor decreases as a function of the frequency of the signal applied to it.

No from that perspective you have a battery that doesn't have a lot of resistance under low frequencies DC in our case. The capacitor has low impedence under high frequencies. So electricity always follows the shortest and easiest path. The high frequency signal will flow through the capacitor and the low frequency DC goes through the battery.

If I had a FFT spectrum analyzer I could easily show this with a graph or two maybe need a third. Not only that I always see this question on this forum. But when it comes down to it a bigger capacitor makes life easier for you lipos. Thats why caps are a good thing.

mulepic 08-23-2013 10:14 AM


Originally Posted by Ivegotklas (Post 12476717)
http://en.wikipedia.org/wiki/Low-pass_filter

From an electrical stand point the cap really acts as a low pass filter. Kinda like on a speaker crossover. The cross over send all the high pitch noise to the tweeter and the low pitch to the woofer. In this case the capacitor acts like a speaker cross over with no tweeter. The high frequencies produced by the ESC during acceleration and breaking get filtered by the capacitor. The low frequencies (i.e. DC voltage) come from the battery.

So how in return do you get better run time and acceleration. The key here is the effect of the cap on the battery. Lipo's are DC, under a PWN driven motor (ESC) the power required to drive the system has lots of transients (i.e. high frequency noise). Batteries have a hard time with producing that power. With out a capacitor the battery would heat up and have high voltage drop accross it. Thus lower run time and less acceleration. The impedence (i.e. resistance and reactance) of a capacitor decreases as a function of the frequency of the signal applied to it.

No from that perspective you have a battery that doesn't have a lot of resistance under low frequencies DC in our case. The capacitor has low impedence under high frequencies. So electricity always follows the shortest and easiest path. The high frequency signal will flow through the capacitor and the low frequency DC goes through the battery.

If I had a FFT spectrum analyzer I could easily show this with a graph or two maybe need a third. Not only that I always see this question on this forum. But when it comes down to it a bigger capacitor makes life easier for you lipos. Thats why caps are a good thing.


How does it impact the heat generated by the motor and esc?

Ivegotklas 08-23-2013 10:51 AM


Originally Posted by mulepic (Post 12476746)
How does it impact the heat generated by the motor and esc?

The battery voltage under load with a capacitor is higher. Thus to get the same power you will need less current. Less current equals less heat.

us4phil 08-23-2013 03:20 PM

Just received the copperhead VX4R.45 I am assuming since the wires aren't marked it doesn't matter what order they are connected to the ESC?
Also when I turn motor shaft by hand should it be smooth or a considerable amount of resistance?
Thanks in advance for your info.

godofcable 08-23-2013 03:31 PM


Originally Posted by us4phil (Post 12477544)
Just received the copperhead VX4R.45 I am assuming since the wires aren't marked it doesn't matter what order they are connected to the ESC?
Also when I turn motor shaft by hand should it be smooth or a considerable amount of resistance?
Thanks in advance for your info.

The motor will feel notchy. As far as the wires, hook them up any way. If the motor turns the wrong way, reverse any two.

aussiek2000 08-23-2013 04:01 PM

In regards to top speed timing. How much does it actually help? How much heat does it build at 5* or so?

mulepic 08-23-2013 04:47 PM


Originally Posted by Ivegotklas (Post 12476848)
Less current equals less heat.

I knew this I just wanted it said by someone else. This needs to be the mantra for the "Electric Off-Road" forum. I built an e-1/5 that was 14s w/ a 120A esc based on this principle.

Cain 08-23-2013 08:04 PM

Got to hook up one of my VTX8's. Was a bit getting used to coming from SP, Castle, and Tekin style setups. But in a good way too :)

I am pretty impressed with the quality feel of the case. But as a side note, make sure you have a GOOD soldering iron as I think it wicks away at the heat. I had to reset my soldering gun tips to get it to work right.

The V-port setup is awesome! I love not having to mess around pulling my receiver wire to do anything. Only thing I hope you guys do in the future is maybe offer that on the case itself.

Now, to the one issue I thought I had resolved but I guess I didn't follow, I thought out of the box I was all set to connect the ESC to my PC, but it appears I need to buy the PC Link. Not a big knock here, I guess I didn't find it clear what I needed.

Lastly, can someone give me a better explanation than what Throttle PWM Frequency is done in the manual? Coming from the world where I can adjust Timing, boost etc, I recall something similar to this on other ESCs and I am a bit lost.

Other than that, I believe I am going to very happy :)

Ivegotklas 08-24-2013 05:55 AM


Originally Posted by mulepic (Post 12477746)
I knew this I just wanted it said by someone else. This needs to be the mantra for the "Electric Off-Road" forum. I built an e-1/5 that was 14s w/ a 120A esc based on this principle.

Yes it does. But I still run 1/8 scale at 4s. Would be far to expensive to buy all those batteries.

Motorman007 08-24-2013 07:36 AM


Originally Posted by Cain (Post 12478256)

Now, to the one issue I thought I had resolved but I guess I didn't follow, I thought out of the box I was all set to connect the ESC to my PC, but it appears I need to buy the PC Link. Not a big knock here, I guess I didn't find it clear what I needed.

So I do need the PC link? I have the Pro Gauge now. I'm still getting all my parts for my EB48.2

EB48.2 - Check
Esc Viper -Check
Rx Futaba 614fs - Need
Motor VF8-Need
Pro9 Cap-Need
PRogauge-Check
Packs-Check
Servo- Check
Transponder-Check
Novak Mod 1 pinions 15t-20t- Need
Tekno 8x1.3 piston - Need
Kyosho Springs Blue F/Orange R-Check
tekno Hubs front and Rear 1mm and 2mm- Need
6mm RCPROPLUS Supra X Gold Bullet Polarised Battery Connectors- Need
http://www.hobbyking.com/hobbyking/s..._5_pairs_.html

JConcepts Finnisher Tekno EB48 Body -Need
Tekno Front Arms-Need
TKR5253 - Tekno RC Aluminum Servo Horn-Need
Viper PC link--Need or not????

I like to buy once even if I have to wait a little.

Cain 08-24-2013 09:56 AM

If you want to make changes to your VTX8 settings on your PC and update the firmware for it , you will need the PC Link from what i am seeing.

However, with 1/8 4S, I haven't really found a need for a lot of the various boosting, etc features That for some ESCs I think you need to modify on a PC. With the EZ Link / Pro gauge, seems like everything I woudl want to set is there.

but having the option to upgrade it would be a big plus, hence the PC Link.


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