A small servo presses the trigger button of 
the camera

But what is after the photo was made?
Fetch down the kite and the camera to start the delay trigger again? It would be better, if a camera with motor drive (or a digital camera) could make one picture after the other in a certain interval automatically.

Here is my solution :
The Servo-Autotrigger.

You trigger with a small servo. This is usually attached to a remote control receiver and moves so as it is steered with the remotetransmitter at the ground. It presses the trigger with its sevo-arm and releases the camera. But the needed control signals, however, don't have to come from a remote control from the ground. One can produce them with a little electronic wiring directly at the KAP Rig in the air too and doesn't need the complete remote control therefore any more.

The Servo-Autotrigger for KAP is only
 55 mm x 24 mm small in size

Funktion of the Servo-Autotrigger:

A servo impulse is usually caused every 20 ms in the transmitter and depending on the position of the control stick of the transmitter. It is between 1 and 2 ms in time.

For example if it is 1,5 ms, then the servoarm is in the neutral position and the camera does not not release. If the impulse is prolonged now for 2 ms, then the Servoarm moves, presses the trigger and releases the camera. After triggering the impulse is shortened again for 1.5 ms and the servo moves to the neutral position again.

Well, the electronic wiring must be able to cause servo impulses with different lengths for the neutral position and the trigger position.

Furthermore it must cause the desired delay which is needed to get the kite into the air or between the photos to reach the camera in another height or to another position.

• The changeable servo impulse with 1 -2 ms.
• The impulse recovery time with approx. 20 ms.
• The delay between the camera triggerings, depending on wish between 6 and approx. 40 sec. or at corresponding choice of C1 still longer.

This three different delays can be produced by the integrated circuit NE555. The circuit NE556 contains two timers.

Testcircuit:

At first I have build a testcircuit on a breadboard to test the funktion and the dimensins of the elements. At the outline of this wiring it was important for me that it works with customary components and no microcontroller must be programmed so an after-building is fundamentally easy. With trimmers the interval time as well as the position of the servo can be adjusted for the neutral situation and the triggerposition. After some tests I then have designed a circuit board for the wiring which is fitted with normal, easily available components.

Construction of the circuit:

Now here the layout of the small board, the mountingplan, the wiring diagram and the parts list with further construction notes for the Servo-Autotrigger.

To get a layout film in the right size and with god sharpnes you have to print the layout in a big size and resize and copy it to an overheadfilm by a photocopier. To get the right size of the film the measure 40 mm must be 40 mm. So you receives a clearly sharp foil with which the PCB can be exposed wonderfully.

More information on how to make your own PCB-Boards you can find in my article: The making of electronik circuit bords.

Powersupply:

There are two different ways to power the ciruit and the triggerservo:

1. With a 9 V E-Block or accu.
For that you have to use the pins X2 for +9V and X3 for GND. The pins X4 and X5 are unused. The voltage controller IC 3 produces the needed 5V for the circuit and the servo from the 9 V of the batterie.

2. With an accu out of 4 cells with a voltage of 4.8V.
For that you have to use the pins X4 for +5V and X5 for GND. The part of the PCB whitch contains the voltage controller and the two capacitors C8 and C9 can be cutted at the dotted line. This version is a few gram lighter because both, the PCB and the accu is smaller.

Adjustments:

With the three trimmers of the circuit you can adjust the Intervalltime (Zeit) this means the time between two pictures, the position of the servo on trigger- and neutralposition.

R1A = Intervalltime (Zeit)
R4 = Triggerposition
R7 = Neutralposition (Ruheposition)

Steps to adjust the circuit:

1. Intervalltime at shortest time = right position of the trimmer

2. Trimmer "Neutralposition" in middle position

3. Trimmer "Triggerposition" to the smallest movement of the servo = left position of the trimmer

4. Swith on the powersupply

5. Adjust the trimmer "Neutralposition" so that the servo-arm is only some mm over the trigger button of the camera.

6. If the servo now moves into the "Triggerposition" you have to adjust the trimmer "Triggerposition" so that the camera triggers. The smaller the movement of the servo, the lower is the needet power, the smaller the accu can be.

7. At last you have to adjust the wanted "Intervalltime" with the trimmer R1A.

How does KAP work now with the Servo-Autotrigger?

You have to adjust the view of the camera on the ground, swith on camera and the Servo-Autotrigger and lift up the kite in the air. The Servo-Autotrigger then causes servo impulses, which drives the servo to the triggerposition and the camera releases. If you use a camera with a motor film transport or a digital camera you get that way a photo made after the other till the film or the chip is full. Since you cannot adjust the look of the camera with the remote control from the ground, the desired object must be aimed by your own mouvment on the ground with the kiteline in your hand.