Webra Picco and 2.4 GHz conversion with original #1271 actuator.

[F2B]

When looking at the internals of the MIC 4427, there is a (clamping) diode at the input, preventing the first FET's gate voltage rising any higher than Vs + ~o.6 volt.
Without any external supply, the input will supply the entire circuit with Vs = Vin - ~o.6 volt, estimate ~4 volt.
This, apparently is also enough to power the output stage, hence your LED lights up.

[MaxZ]

I can see it now. Thanks Bruno, I will sleep again tonight.....

Edit: I did lose some sleep last night trying to work out what will happen when I connect a low impedance load, like the Picco. Will it draw too much curent from the Arduino port and destroy it? I could not work it out, so I decided to install a 1K resistor between the two chips to curb the current just in case.

[MaxZ]

Hi guys,

The transmitter is done. Throttle is by means of a 3-position switch, the mid position is adjustable with a trim pot which is accessible from the outside, and doubles as a push button.
I have added a countdown timer to stop the motor when it expires, the owner wanted the possibility to practise for gliding contests with limited motor run. A short push on the button will raise the setpoint by 10 seconds every time, a long push will reset the timer to zero. The cutoff will only affect the full power setting. Returning to the throttle closed position will reset the countdown, but keep the setpoint.
Calibrating and reversing are as usual (rudder only), but as the rudder pot is not self-centering I have added a warning and a required acknowledgement before you actually reverse the channel. The pot turns really light, so the chance that it is in an extreme position when you switch on is real.
Testing the actuator is next.

Cheers,
Max.

[MaxZ]

Hi again,
I did test the actuator now, and everything is working as expected. Before that, I changed the connection wires as they looked really shoddy. I must say, the innards of the actuator were not quite what you would expect from typical German engineering and workmanship (by a long shot....). The soldered connections to the coil were just that, no lugs or anything solid to connect to, and the wires were "secured" by pushing those into the plastic base with a hot soldering iron! I replaced that with a blob of hot glue.
I will soon post a video of the whole thing.

Cheers,
Max.

[MaxZ]

Video:



I did attempt to narrate it, but I got bogged down on some of the descriptions, so I will spare you that.
The end of the video shows the throttle action, represented by a servo, and the timed cut off at 10 seconds. You can stop at 2:05, the rest is repetition. I have to find out how I can edit the vid online to cut it off.

This is how the actuator looks on the inside. In front you can see a (smaller) stripped down version, showing the rotating magnet. The delivered torque is really small, even when powered by a 3s LiPo. Surprisingly, I can only detect two very small pieces of iron wire-like material on either side to attract the magnet back to its rest position when the coil is de-energized, which would limit the torque in that direction. Makes you wonder if you can soup it up by adding more bits of iron.......

Cheers,
Max.

Edit: something wrong with embedding the video? Fixed it for you Max - Mike_K. Thanks Mike.