Viper RC -
#2522
#2523
It wasn't my intention to ruffle anyone's feathers over who has more FET's. As I said before I was using it as an example. Thanks for the heads up Randy, I appreciate you clearing up the FET number. And my user name on here and RCSC are a good indication of how much I can actually eat. 

#2524
#2525
#2526
Tech Master
iTrader: (5)
Joined: Nov 2003
Posts: 1,850
So, my Viper VTX10R quit working today, right before the qualifiers started. Ran fine all day yesterday, and throughout practice, then failed. It turns on and initializes with two double beeps, then nothing. I get steering, but no throttle. The N and R LEDs are flashing, but I did not see that error code described in the instructions. What does the N and R LED flashing mean? I tried a different sensor cable, and even plugged the sensor cable into a different motor. Running a Durango DESC410R with a Novak 4.5 550. Had to quickly pull the Viper out and put my backup RX8 in before the first round started. Qualified BQ, won the B, bumped to the A, and finished 2nd, in a very competitive field. Gave the Viper to the hobby shop guy I bought it from to send it back to Viper for repair. Hope Viper gets their reliability issues resolved, the ESC is great when its working.
#2530
i think alot of this could have been avoided by just simply stating that the esc has x amount of fets, although u may not mean it to be a negative comment, when u say it has twice as many fets as another esc, you are basically saying yours is better because it has more fets then the other. i run a rx8 in my 1/8 and its a great esc, i also had a vtx10r in my shortcourse, also a great esc, just put a product out there and the products feedback will speak for it self
#2531
I was just wondering if your in R&D for a 4 pole 1/8th scale motor? Beacuse I was really set on buying the 1/8th 2 pole motor. But after how I saw my buddy Dean's buggy running yall's motor it was a turd. We had the same exact buggy, electronics, lipos, besipe the motor's I was running a tekin 1850kv, and he was running your VSE1800B 1800kv motor. And it was acting as slow as a Honda civic with the E Brake's on. And it had a overheated issue so he went down on gearing a little bit it kind solved it. But it made it slower even more beacuse of the gearing. But it still did'nt get anymore torque when he drop the gearing..
#2532
Tech Adept
Joined: Aug 2010
Posts: 166
FETClicky clicky.
It has relatively low gain-bandwidth product.
MOSFET has a drawback of being very susceptible to overload voltages,thus requiring special handling during installation.
So the Viper has more of these disadvantages?....I am no electrical engineer....what the heck does it mean if it has more or less fet
2. Theory of DC motor speed control
The speed of a DC motor is directly proportional to the supply voltage, so if we reduce the supply voltage from 12 Volts to 6 Volts, the motor will run at half the speed. How can this be achieved when the battery is fixed at 12 Volts?
The speed controller works by varying the average voltage sent to the motor. It could do this by simply adjusting the voltage sent to the motor, but this is quite inefficient to do. A better way is to switch the motor's supply on and off very quickly. If the switching is fast enough, the motor doesn't notice it, it only notices the average effect.
When you watch a film in the cinema, or the television, what you are actually seeing is a series of fixed pictures, which change rapidly enough that your eyes just see the average effect - movement. Your brain fills in the gaps to give an average effect.
Now imagine a light bulb with a switch. When you close the switch, the bulb goes on and is at full brightness, say 100 Watts. When you open the switch it goes off (0 Watts). Now if you close the switch for a fraction of a second, then open it for the same amount of time, the filament won't have time to cool down and heat up, and you will just get an average glow of 50 Watts. This is how lamp dimmers work, and the same principle is used by speed controllers to drive a motor. When the switch is closed, the motor sees 12 Volts, and when it is open it sees 0 Volts. If the switch is open for the same amount of time as it is closed, the motor will see an average of 6 Volts, and will run more slowly accordingly.
As the amount of time that the voltage is on increases compared with the amount of time that it is off, the average speed of the motor increases.
This on-off switching is performed by power MOSFETs. A MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) is a device that can turn very large currents on and off under the control of a low signal level voltage. For more detailed information, see the dedicated chapter on MOSFETs)
The time that it takes a motor to speed up and slow down under switching conditions is dependant on the inertia of the rotor (basically how heavy it is), and how much friction and load torque there is. The graph below shows the speed of a motor that is being turned on and off fairly slowly:
You can see that the average speed is around 150, although it varies quite a bit. If the supply voltage is switched fast enough, it won’t have time to change speed much, and the speed will be quite steady. This is the principle of switch mode speed control. Thus the speed is set by PWM – Pulse Width Modulation.
#2533
I am looking for a new speed controller...The one I am currently using has no timing or boost and I am getting blown away with the tekins that the other racers are using...I like the features the VTX10 has especially the Pro Gauge...
My question is this...How does the VTX10 compare to the Tekink RS...I don't want to spend this much money and still have them beating me because they're faster...
Any help on this question is greatly appreciated...
Racer53
My question is this...How does the VTX10 compare to the Tekink RS...I don't want to spend this much money and still have them beating me because they're faster...
Any help on this question is greatly appreciated...
Racer53



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