DX6i auto timer

I built little mod (hack) for my Spektrum DX6i transmitter as I always forget to turn on my flight time timer when I start flying. Now I can relax as the mod will keep track of the throttle stick position and automatically trigger trainer switch based on the throttle position threshold (which can be easily changed). I though it might be usefull for others as well. Even though its a quite easy project you still need some basic knowledge in electronics.

 Hardware:

I chose AVR microcontroller as I had it laying around in my parts bin.

Parts you would need:

• 1x ATtiny13 microcontroller
• 1x 8pin dip socket (or you can solder the chip directly - just do not overheat it)
• 2x 10k resistors
• 1x 100nF capacitor
• 1x buzzer 7.62mm leg spacing (which emits some kind of sound at 3.3V)
• 1x 6pin 90° male header connector (or you can solder cables directly)

Schematic:

I build this cable where I just solder two wires to the switches and the rest is connected through intercepting connection so I can replace throttle stick assembly easily again if needed (yes my potentiometer went wrong at the best possible time... bloody Murphy) 

Trainer and Flap wires are soldered on the pad which does not have the black cable connected to it. If you want to use different switch for device activation just solder cable from pin 3 to any other switch you like.

Power to the device is obtained from the throttle stick cable plug which has:

• black (-)
• yellow (throtle position signal)
• red (+3.3V) 

Printed circuit board (PCB):

If you want to fabricate your own PCB you can download DipTrace source files and print it from there (link below). How ever if you don't mind waiting a bit you can order it directly from OSHpark for about 6$ (including world wide shipping) for 3 pieces - so you can share with friends :)

OSHpark: http://oshpark.com/shared_projects/mnQSmwfr

Design sources (in DipTrace): dx6i-autotimer.zip

Software:

To upload firmware you would need AVR programer or (arduino). ISP pinout on the device from the top (left to right) is as follows:

• 1 VCC +5V
• 2 GND
• 3 MOSI
• 4 MISO
• 5 SCK
• 6 RESET 

I post it here in the spirit of flitetest free plans so feel free to build, modify, hack as you like.

DX6i autotimer mod by Sokol is licensed under a Creative Commons Attribution 4.0 International License.