Power monitor and Lost and Found Transmitter(LPD frequency range)This project incorporates 3 helpful units for model air plain pilots.
(click to the pictures)
- Battery power monitor
A dual color LED provides information about the current battery condition. The color and the blinking frequency informs about how good charge still is. The power monitor provides a kind of memory for the lowest voltage ever reached since power has been turned on, even in the air. There are 5 different levels.
- Battery power empty warning during flight
Before the battery voltage of the plain reaches the lowest level, an on board 433 MHz transmitter starts a low voltage warning . Any 433 LPD hand held receiver can receive the signal.
- Lost and Found monitoring if plain escaped
Via a RC channel , a 433 MHz transmitter can be turned on to provide a FM signal for locating a lost plain. The transmitter emits an alternating RF signal with 4 different power levels automatically . This allows locating of missing plain in a wide distance range.
HW: A MSP430F1232 controls a Hope RFM02 transmitter module.
Features: Size : 30mm x 43mm (without box) RF range : 4 channels 433.400 MHz LPD CH 14
433.800 MHz LPD CH 30
434.200 MHz LPD CH 46
434.650 MHz LPD CH 64
Power range : 4 levels - 13 dBm
- 7 dBm
3 dBm ( with optimal environment)
Power consumption : Transmitter active : 35 mA ( full power setting, LED on) Voltage : 3.5 .. 5.4 V external power (via a standard RC connector) Battery power monitor :
Battery color blinking frequency RF low voltage warning
> 5.0 V green slow off
> 4.8 V green fast off
> 4.6 V orange slow off
> 4.4 V orange fast off
> 4.2 V red slow on
< 4.2 V red fast on
Look at the schematic here. (pdf)
The assembly drawing of the PCB can be found here. (pdf)