Building an Intervalometer for the Panasonic GF1
Or, Detonator? I Hardly Knew Her! (Don’t Bring This Through Security)
Monique had the great idea to shoot a time-lapse of our move in together, and I was excited to get to work on a new little project. It was quick that I remembered that my camera (and most others) don’t have the ability to take photos at regular intervals (“Please buy our \$50 remote!”). If this wasn’t being done while we were moving I would have just bought an app for my phone but I also figured that it couldn’t be that hard to build a simple timed trigger. After looking at some camera stores and Radio Shack for an intervalometer I ended up buying a 555 timer, 2.5mm plugs and some pushbutton switches at RS to build my own.
Panasonic uses a voltage divider and a 4-conductor 2.5mm plug for remote triggering. I found a basic schematic of Panasonic remotes here. I couldn’t find a 4-conductor plug at RS (Mouser and DigiKey both have them) but you can use a 3-conductor plug and just not insert it all the way. That guide mentions that you can use common resistor values in place of the strange values mentioned (Panasonic, you jerks) but I just put resistors in series to get closer to the spec values.
The basic premise of the circuit is to use the 555 timer to output high at regular intervals (10s, 30s, etc.), activating a transistor which serves as a switch closing the “shutter” portion of the voltage divider and triggering the shutter on the GF1.
The 555 is being used in astable mode, which will generate a square wave with regular intervals. There are independent time spans for the output being high and low, and using a diode across R2 allows the delay between high signals to be longer than the length of the high signal itself (i.e. a duty cycle of less than 50%). I set the interval between shots to be about 15s, and the trigger itself lasts about 1s (to make sure that the camera fires, and I put it in single-shot mode to prevent duplicates). The values that gave me those times are a 22µF capacitor (C1), 10kΩ for R1 and 1MΩ for R2. You can adjust the interval between shots with R2, and it’s linear.
There’s a schematic up on Circuit Lab here:
I can’t see myself using this very often but it’s a useful little device to have around. The pushbutton allows manual triggering of the camera if you need a shot on the fly, and the LED lights up when a shot is triggered by either method. Everything fits nicely in a little tin I had laying around and will probably last forever on the 9V battery. Timing circuits based on charging a capacitor are generally imprecise for long intervals, but for my uses it works just fine. I might move the circuit onto perfboard and add a linear potentiometer (I only have log ones right now) to adjust the timing without swapping resistors if I feel the need.