Electronic Workshop

Before discovering Kite Aerial Photography, electronics was already one of our main hobby. This explains that, after some unsuccessful attempts of mechanical release control with a dedicated line, we implement electronic release systems.

History:

  • NE555 timer
    Our first release timer (1988) was based on the popular NE555 timer. A potentiometer was used to adjust the delay between 1 and 10 minutes. The camera was a MINOX GT35.

  • Discrete logic parts:
    This generation based on 74HCXX or CD40XX logic parts was implemented in the first version of the panoramic cradle. This concept is complex to design, so we move on to microcontrollers.

  • MOTOROLA 68705P3S microcontroller:
    MOTOROLA 68705S microcontroller was very popular in France in years 1990-1994, because of its use in a pirate TV decoder. Advantages were its very low price (under 10 euros), and the large availability of assembler and programming tools. Drawbacks were its relatively high power supply consumption (100mA) and its UV erase process, which requires 15 minutes before a new programming.

  • MICROCHIP PIC microcontrollers:
    PIC 16F84 is member of a new generation of microcontrollers introduced in 1993 by the company MICROCHIP. PIC16F84 is the perfect part for the electronics hobbyist due to the low cost of the part and the free availability of development software. It is amazing to see the number of various functions a single PIC16F84 can do:
    • a sophisticated timer (see robot cradle).
    • a PWM generator to control servos.
    • a coder / decoder for HF digital link.
    • a video generator (see video altimeter).
    • and lots of other things, only limited by imagination!
    New and more powerful microcontroller are today available: AVR from ATMEL and SX from SCENIX for instance. For more complex functions (see video cradle for instance), we use MICROCHIP PIC16F87X, whose software is compatible with PIC16F84, or ATMEL AT90S1200 or 90S2313.


Key electronic parts:
  • HF radio links:
    Most Kite Aerial Photographers use radio control systems designed for hobbyist in their photograph systems. This is by far the simplest solution for kapers who don't want to go into complex electronic design.
    For our part, we use HF transmitter modules produced by European companies AUREL, MIPOT or RADIOMETRIX. These modules are low cost (10 to 20 euros) and make possible the design of reliable and compact digital link, even if you are not a radio specialist. Controlled by a microcontroller, they make possible upward links for cradle control, or downward links for parameters transmission (altitude, wind speed). Disadvantage of these modules is the fact that they work on a single frequency (433.92MHz or 868.3MHz), what creates a risk of interference with other systems using the same channel, as alarm systems or walky-talkys do. We met heavy interference problems with AM models (Amplitude Modulation) some years ago, that we resolve by the use of FM models, less sensitive to interference.

  • Alphanumeric displays:
    We use LCD alphanumeric displays, often 2 lines of 16 characters type. Controled by a microcontroller through a 6 wire bus, they can display helpful data for the kaper, like number of picture, altitude, battery voltage...

  • Sensors:
    We use sensors to get physical data on the cradle that can help the kaper in the control of the camera and in the decision to take or not a picture. Sensors we already implement in our cradles are:

  • On screen display:
    Adding data in the video picture, as we can see in camcorder viewfinders, is a real plus. This function is possible with a specialized circuit named "OSD" (On Screen Display). Combined with a video synchro separator ELANTEC EL4583, the ST-MICROELECTRONICS STV9426 contains in a DIL 16 package all functions to display alphanumeric characters in a video picture. The STV9426 programming through I2C bus is quite complex, but results are great, as shown in the video cradle page.
    on screen display
    on screen display

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