Standard Navigation Lights circuit drives LEDs directly from the PIC. This limits
maximum current to about 20mA per output. Outputs include 2 asynchronous strobes, a
Landing Light, and 3 permanent Lights. Three servo positions are detected,
selecting either all outputs ON, all but Landing ON, or all OFF (use channel 5 to control.
Mix in the throttle channel to turn on the Landing Light at low throttle!).
LEDs should have series resistors in their leads (in addition to the on-board 100 Ohm
resistors) to set the desired current. Depending on LED requirements, it may be
possible run two or more LEDs in series or parallel on the same cable.
PIC12F629/75 can be programmed in system (especially useful for SMD version). Supply power
through the servo connector (+5V, GND, and Vpp to signal input), and Clock/Data through the
LED outputs. Keep wiring short!
High Voltage Navigation Lights circuit drives LEDs through external transistors.
You can use a separate LED supply voltage (eg. 9V dry cell or 3S Lipo). With high
voltage you can drive several LEDs in series, eg. 3 x RED/YELLOW or GREEN, 2 x BLUE
or WHITE, depending on how much voltage each LED consumes. RED, YELLOW and GREEN LEDs
typically use 1.7~2.2V, BLUE and WHITE LEDs use 3.5~4.2V each.
LED current is determined by three factors:-
For example, if you are using a 9V battery with 1 RED and 1 GREEN LED in series, and
you want the LEDs to draw 20mA, the required resistance is:-
- Resistor in series with the LED(s)
- Voltage dropped by the LED(s)
- Supply voltage.
(9V - 1.7V - 2.2V) / 20mA = 255 Ohms
Source code (PIC12F630/75)
HEX file (PIC12F675)
I designed this circuit for use with a gas Helicopter. It obtains high current output using discrete power FETs.
The servo input controls 2 Strobes and 3 fixed outputs. There are also 2 continuous (non-switched) Strobes. When
a receiver battery is used the LEDs can be very bright. If using a BEC, please verify that it can handle the extra
current wihout overheating!
Source code for Helicopter Navigation Lights (PIC12C508/9 or 12F630/75)