Dances with electronics

In which your humble narrator manages to get his shiny new Arduino to make the Pentax K10D go “click”.

After some digging around I managed to find out how the remote cable on the K10D is setup, 2.5mm stereo jack.

Tip – Shutter
Ring – Focus
Sleave – Common

All nice and simple, close ring & sleave, watch the camera focus. Close tip and sleave, click. All nicely tested with a bit of wire and a nice fresh jack from Maplin. The important part of the circuit is I don’t want anything from the control side spilling over into the camera side, frying the camera would be a bad thing.

Enter the optocoupler, a nifty little device which allows control on one side to open or close a circuit on the other with no crossover of circuits.

The circuit

U1 – 4N25 optocoupler
R1 – 470 ohm
R2 – 560 ohm


The code is effectively the blink test just slightly tweaked for the LED circuit, nothing exciting or sexy yet.

Optocoupler based firing mechanism

// Control PIN
int pinLED = 11;
int pinCAM = 10;

// the setup routine runs once when you press reset:
void setup() {
// initialize the digital pin as an output.
pinMode(pinLED, OUTPUT);
pinMode(pinCAM, OUTPUT);

void loop() {
delay( 1000 ); // Delay one second
digitalWrite(pinLED, HIGH);
digitalWrite(pinCAM, HIGH);
delay( 1000 ); // Delay one second
digitalWrite(pinLED, LOW);
digitalWrite(pinCAM, LOW);


Next… seeing if I can get the IR LED to fire the camera.