This project, called “Mini-Beacon”, is a miniature programmable LED Flasher that is based around the PIC microcontroller. This project grew out of an idea and recommendation posted on RunRyder.com
. The Mini-Beacon basically simulates the light emitted from a rotating light beacon such as those used in older police cars and fire engines. As seen from the observer’s perspective, as a real rotating beacon revolves, a dim light slowly ramps up brighter and
brighter until a flash is seen (light facing directly toward observer), then as it continues rotating, the light slowly dims out and a pause is observed until it repeats over and over again.
Well, the “Mini-Beacon” simulates this exact effect! The user can also choose 1 of 12 different flash patterns to be repeatedly displayed. These patterns include slow, medium and fast rotational beacons (ramp-up & ramp-down speeds), and 3 different selectable flash patterns (single, double and triple flash). This selection is made by simply shorting a small jumper on the driver board. This setting is retained in memory so that every time the “Mini-Beacon” is powered up, it will display this pattern.
If this was not enough, the “Mini-Beacon” also allows you to run it in “free-running” mode (connect battery and it repeatedly flashes), or you can control it (on/off) using a spare receiver channel on your R/C receiver (you can use a transmitter stick or switch). The setting is accomplished using two small jumpers on the board and is described below in detail. Additionally, and most likely most important… you can also control the Mini-Beacon using a “Mini-Flash” Controller by simply plugging them together!
Design Criteria Summary:
1) Design a simple, cheap but effective “Rotating Beacon” simulator/driver
2) Design so user can easily choose 1 of 12 flash patterns
3) Lightweight and simple to build (DIY)
4) Circuit powers off of existing R/C servo connector
5) Use servo signal to turn on or off the flashing Beacon effect
6) Powers a bright LED (around 600mA max… a one (1) watt Luxeon looks great!)
7) Listen to customers and their needs! 🙂
Parts & Tools List …
1) One (1) PIC 12F629 Chip (preprogrammed with Mini-Beacon code)
2) Two (2) 10K ohm resistors
3) Two (2) 2.2K resistors
4) One (1) Servo Lead/Pigtail wire for Mini-Beacon
5) Four (4) 2 pin header (male) – 3 for Jumpers, 1 for LED/output connector
6) One (1) 2N2222 or PN2222A NPN Transistor
11) One (1) two-row header (mating connector for Mini-Beacon output pins)
12) One (1) piece of heat shrink tubing for assembly
13) Two (2) Shorting Jumpers (one for run mode and the other for programming)
Testing and Operation Instructions…
Download the Mini-Beacon User’s Manual below (in PDF format… Adobe reader is required)
The Mini-Beacon controller has a servo cable which can either be plugged into a spare channel on your Radio Control receiver (Rx) or it can simply be connected to a 5-6 volt power source. Opposite of this servo cable lies a two pin connector (inline with board) that is used to connect your beacon LED. The onboard output driver/transistor is capable of providing around 600mA to a connected load. A typical 5mm LED draws 20mA while a 1 watt Luxeon emitter draws an average of 350mA. 3 sets of jumpers/pins located on the Mini-Beacon are used to either set the flash pattern (1 of 12), set the servo control function, or allow the controller to free-run. First thing you will obviously need to do is connect an LED to the Beacon output pins (see picture above, observe polarity). Be sure to use the proper series current limiting resistor inline (series) with one of the LED leads (typically 56-120 ohms).
There are two ways you can operate the Mini-Beacon controller. You can either set it up so it’s in “free-running
” mode (apply power, and it flashes continuously until power is removed), or you can connect it up to a spare R/C receiver servo channel
and control (on/off) the flashing pattern of the beacon using a stick, slider or switch on your transmitter (aka Servo Control Mode). The Mini-Beacon has two jumpers that allow you to set these two functions (labeled “Servo Jumper” and “Free-Run” on the picture above. Only one of these jumpers should be connected at one time.
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