Introduction: AltiSafe CTR for RC Aircraft

This Instructable will show you how to turn a Quanum Lipo Battery monitor into a remote Maximum Altitude Alarm. (AGL altitude)

Simply attach the modified Quanum transmitter to the balance leads of the aircraft lipo and the Quanum receiver will vibrate when the aircraft altitude is greater than the configured limit (either 40m or 120m). This is particularly useful when flying within a CTR (near aerodromes).

Theses limits can be easely modyfied for other needs in the C Arduino firmware.

Parts required:

  1. Quanum Lipo Monitor
  2. Pololu A-Star 32U4 Micro : Arduino compatible micro-controller; the C code is included at the end of these instructions.

  3. BMP180 or similar barometric altimeter

  4. PCB and components
  5. 4 X capacitor 0,1 uF
  6. 1 X capacitor 10uF 20V
  7. 2 X resistor 4,7K
  8. (FIRST VERSION) 3 X resistor 1K
  9. 1 X diode 1N4148
  10. (FIRST VERSION) 1X SH108N or BSS138 or compatible MOSFET chanel N 'logic'
  11. (SECOND VERSION ) 1X MOSFET ZXM61P03F or compatible MOSFET chanel P 'logic'

Cheap, about $20.

New version with link described at the end.

Step 1: Remove Blister

Simply split the blister at the side near the antenna. Then make a cut to be able to access the 3 first pins.

Step 2: Cut Off All the Pins in Preparation for De-soldering

Cutting the pins off first, will make it easier to de-solder the connector in the next step.

Step 3: Add Fresh Solder to Help De-soldering

Set the soldering iron temperature a few degrees higher than normal, e.g. 370C.

Then put fresh solder on all pins.

Step 4: Remove Pins

De-solder the pins one by one while pulling them out with tweezers.

Step 5: Clear the Connector Holes

That can be done in many ways, the easiest is with a solder pump.

Step 6: Rebind the Blister

Since the blister is still ok, we can reuse it. Use transparent tape to tighten it and hold it in place.

Step 7: Populate the PCB

The PCB is described at EasyEDA site.

You can download GERBER files or order it there.

The picture here shows my prototype version. The final version on EasyEda is greatly enhanced and beautiful ;-)

The connectors can be soldered later.

Step 8: Assembling PCB and A-Star Together

It's easy to use some header pins or little cable.

You can set the soldering iron temperature to a normal one (320C).

Solder all 7 pins for the Pololu A-Star and 4 pins for the BMP180.

Step 9: Remove the Plastic After the Soldering

After soldering all the pins on one side, remove the plastic.

Step 10: Solder the A-Star and the BMP180 to the Pcb

Align and solder the Pololu A-Star and the BMP180 to the pcb.

Step 11: Trim All the Pins

Trim the pins after soldering.

Step 12: Solder the Pcb and the Quanum

Align and solder the pcb and the Quanum together, then solder the 3 pins which pass through the two boards.

Step 13: Upload the Firmware...

Use the Arduino IDE upload upload the firmware.

First install the BMP180 library from Adafruit.

Wire.h ( normaly already in the Arduino IDE by default )



Step 14: Upload the Firmware...

Install the Pololu A-Star 32U4 Micro drivers in the Arduino IDE.

All instructions here :

Step 15: Upload the Firmware

Download the attached file and open it in the Arduino IDE.

Step 16: Upload the Firmware...

Plug the USB cable.

Open the Arduino IDE, configure the port and the board as described in Pololu site.

Upload the firmware.

That's all there is to it!

The last step is to read the user manual (last step of this instructable;-)

Two important things:

  • Be sure to check the polarity of the battery when connecting it!
  • Chose to plug the jumper or not, to set the altitude alarm
    • with jumper = 40 m
    • without jumper = 120 m

Step 17: User Guide

Download the file.

Step 18: New Version With Full Quanum Monitoring and Simple Plug.

New version with full Quanum fuctionality, see :

Version with PIC, see :

The MosFet transistor is a P chanel 'logic' MOSFET: ZXM61P03F or compatible.

Here is an link: