hsign, sky advertising with a drone
This project is released under the GPL license
designed and build a better text display, this one has color
old one here:
it is hard to take a picture of it, the camera blurs it and removes the color, anyways:
Will do to announce 2017
But dangerous flying it will be with all those fireworks...
The test text was *SKYNET* in a different color for each character...
Flown manually at high speed.
circuit diagram, the 1k resistor has been changed to 220 Ohm, put a Schottky diode in the 5 V to battery input line:
Build it, top view:
The idea is that you hang this under the drone, it will flash the LEDs, and when the drone moves it shows like readable text.
Landing procedure is now a bit more complicated.. move slightly sideways so the board turns horizontal.
Have auto pilot hover at about a meter and a half or so, then switch to manual.
Current consumption on average is about 30 mA, this because the LEDs are flashed on for only a short time.
The circuit may be a bit intimidating as it has
9 NPN transistors
8 PNP transistors
3 power MOSFETs
1 Microchip PIC 18F14K22 micro computer
1 voltage stabilizer
8 RGB (5050 type) LEDs.
In retrospect I should have made a PCB, anyone?
The weight is still only 20 gram.
The power MOSFETs could be low power 1A logic level types, but I only had these,
and did not want to wait for weeks for ebay, so then I decided to use these as hinges to hang the board from.
So those MOSFETs go on top.
The bottom LED is only on for true descenders in the font, so off most of the time.
In the asm source you can find the calculation for the speed you need to fly to get nice looking characters.
It is about 3.4 m/s or 12.3 km/h
To fly a specific pattern and speed I use the auto pilot I designed here:
Building this requires a steady hand, good vision, patience, took me a day.
I check every connection with a magnifying glass.
Writing the software took me an other day, debugging an hour.
I made a little cable with an ebay USB to serial adaptor, so I can put it in a PC USB port and configure the text to be displayed:
Text is saved in the chip EEPROM, so preserved when power is disconnected.
You can set 7 different colors for each character, the maximum is about 120 characters, but shorter messages work better,
Serial communication with the thing is at 115200 B 8 data bits, 1 stop bit, no parity, it should run on the USB 5 V.
Type h for help
DO NOT CONNECT IT TO THE MAIN BATTERY AT THE SAME TIME WHEN CONNECTED TO THE PC USB TO SERIAL ADAPTOR, that will blow up your PC.
Maybe I should put a Schottky diode in series with that USB 5 V line.
The thing will work on one lipo cell, 2 lipo cells in series (like the Hubsan uses), and 3 lipo cells in series.
It will be brighter with more cells.
I ordered a cable so it can connect to the 7.4 V Hubsan battery charge balance connector.
The asm code for Microchip PIC18F14K22, this is NOT for MPlab, I use gpasm in Linux:
And for those who cannot assemble it, here the hex file:
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