Ribble's blog archive for August, 2012 - RC Groups
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Archive for August, 2012

V911 Notes 01

Posted by Ribble | Aug 16, 2012 @ 03:02 AM | 8,201 Views
V911 Binding
Newer Version V911 Transmitter
Origami 2k-2k-1k Transmitter Rudder Modification - Reduces Rudder Throw
Gradual Rotation
Binding Yellow V911 Helicopter
V911 Stock Batteries
USB Hub Charging Batteries
Transmitters That Bind And Fly V911 Helicopter
V911 Wind-Surfing

V911 Binding
Transmitter off, throttle minimum
Helicopter on
Transmitter on quickly while V911 LED is blinking fast
You may have to turn the transmitter OFF and ON after V911 LED blinks slow again
V911 LED is on solid after good binding.

Newer Version V911 Transmitter
The original V911 transmitters moved the rudder so much that the helicopter was hard to control. The newer version reduced how much the rudder stick causes the helicopter to rotate and makes flying the V911 much easier. In low rates, the newer version transmitter shows two tabs on the LCD display for full left or full right rudder.
Night flying and reduced current draw. Numerous measurements
V911 TX Mods

Battery = 7.61v = 6x NiMh LSD 1.2v 2200mah AA cells
76.1ma = Normal LCD off
92.5ma = Normal LCD on
100ma = Normal Beeping
33.1ma = Current into 3.3v voltage regulator Vin = 5.13v ... RF Input power ~ 3.311v x 33.1ma = 110mw (about 20dbm)
13.1ma = 5 Red LEDs Vf = 1.817v

Origami 2k-2k-1k Transmitter Rudder Modification - Reduces...Continue Reading
Posted by Ribble | Aug 16, 2012 @ 01:57 AM | 7,366 Views
Transmitters That Bind And Fly V911 Helicopter
V911 Wind-Surfing
Motor Overheating
Gyro Test
Spins nose-right (clockwise) problem
Rudder Fake-out
Mixing Arms Reversed
Troubleshooting And Other Information
Stuck Servo
Servo Repairs
V911 Helicopter Printed Circuit Board (PCB)

Transmitters That Bind And Fly V911 Helicopter
Stock V911 transmitter (and V929 quad transmitter), still best bang for bucks.
Turnigy 9x and clones
FS-CT6B - What I use when wind is steady, allows hands off hover pointing into wind.
Unconfirmed report that Trex 100 is "fully compatible"
FS-T6 reportedly

In my opinion, the best for price, performance, ease of use, is the stock V911 transmitter. But then I only fly V911's in low rates windsurfing outside, Elevator trim full forward.

V911 Wind-Surfing
For forward flight with the V911, push the nose down and add throttle. Throttle makes it go faster as well as maintaining altitude.

When playing in the wind, keep the nose down or the V911 will float away in the wind. Control forward speed with throttle. Practice nose-left (counter-clockwise) turns to circle around and dive back into the wind. Nose-right turns are easy but hard to pull out of because the V911 picks up too much speed.

Motor Overheating
To check for motors overheating, touch the main motor and kiss the tail motor. Touching tail motor to your nose also works quite well, but my nose isn't calibrated for heat. After you kiss the tail motor, get in the habit of blowing air into...Continue Reading
Posted by Ribble | Aug 07, 2012 @ 01:20 PM | 6,643 Views
Solder bridge the Motor Overload Protection System (MOPS). Suggest scraping some green enamel and splash solder across, right below the two MOPS leads (white line between leads). This grounds the source leads on the two motor FETs (like on the DH9104) Do not remove the MOPS orange loop.

You can put a wire jumper across the MOPS connections, but you stand a chance of ruining those connections, which are critical. So create a solder bridge below the connections. The solder bridge will have some resistance and there will remain some minor motor protection. To later undo the solder bridge, move the soldering iron down the gap between the enameled copper.


9116-PCB-Bottom 9116-PCB-Bottom

MOPS leads - Scrape green enamel below and solder bridge
>I've put on a solder bridge and that solved the problem. I can now spool up to full power without any cut-out affect.
>It was recommended only to do this with the stock battery - my plan is to use a 900mah 20C (40C burst) battery.

Adding more battery mah with a battery that weighs the same as the stock battery does not add any additional workload. A higher "C" rating allows you to fly harder, though the average workload will still be about the same - unless you use the additional available power to fly straight up for a long time, or stall a motor by not turning throttle off upon crashing..

Adding more battery mah with a battery that weighs the same as the stock battery does allow flying longer with added...Continue Reading
Posted by Ribble | Aug 07, 2012 @ 01:16 PM | 5,774 Views
The servos run off the +5v voltage regulator. You can short circuit the voltage regulator and it will just limit the current and work fine when the fault is cleared. Shorting the voltage regulator would drop the gate voltage on the motor switching FETs and turn them off, stopping the motors.

The servos have +5 volts on the center pin (of three) and you can plug the servo connector in backwards with no damage, the servo just won't work. Someone a while back was using a jumper wire to short the servo connector and all it did was reset the DH9116 receiver.

Sounds unlikely that a bad servo could cause damage to anything else.

What will kill the circuit board is stalling a motor. Kill the throttle before you crash. Stalled motors will suck up all the amperes that the LiPo or Li-Ion battery can provide and with a good battery, something has to burn out. It can happen faster than the Motor Overload Protection System (MOPS) can act.

DH9116 printed circuit boards are quite rugged and take much abuse.
Posted by Ribble | Aug 07, 2012 @ 01:11 PM | 5,638 Views

Yes, MOSFET - Metal Oxide Semiconductor Field Effect Transistor.

In the beginner section, one should not abbreviate. Spelling out what MOSFET stands for only makes it worse.

In the case of the DH9116, they are power transistors that are controlled by an electrical charge on the "gate". Put zero volts (ground) on the gate and the transistor turns off (turns very off, like it isn't there). Put +5 volts on the gate and the transistor turns on (turns very on, like a direct short). The gate only needs a voltage and no current, so the power needed to control the MOSFET is practically zero watts.

Fantastic devices. The two MOSFETs on the DH9116 printed circuit board can switch (I seem to recall) 80 amperes to turn the main and tail motors on and off.

A short circuit dissipates no power. An open circuit dissipates no power. The MOSFETs only dissipate power during switching, the transition between a short and an open.

But voltage spikes from the motor's inductance during switching will kill a MOSFET. So, across the main and tail motor connectors are "snub" diodes to short motor spikes.

Enough electronics. MOSFETs are such a mystery to RC helicopter pilots, but are as vital as the LiPo batteries.