I’ve got a growing list of camera-related things I’d like to try, and the lack of a way to trigger the shutter for my Panasonic Lumix G1 has become a real annoyance. Unfortunately, Panasonic only offers one option, a wired remote shutter release that costs $80, though you can get it some places for a mere $50.
Fortunately, there’s another option, detailed in this blog post:
It’s a simple multi-resistance control, connecting various resistances across one circuit and allowing multiple functions to be controlled with one pair of wires…the second “ring” contact and the “sleeve” contact of the 4-contact 2.5 mm TRRS (“phone” or “phono”) plug. I’m not sure the high resistance has any use, it may allow the camera to detect that an external shutter release is plugged in. Closing the circuit with a 5 kohm resistance signals a half press of the shutter button, and a 2 kohm resistance signals a full press. A few resistors is all that is required to convert it to switch closure control. The second ring contact (connected to the 30-40 kohm resistor) appears to be the ground…this is unimportant if using relays or pushbutton switches, but needs to be accounted for if using transistors or optoisolators.
The main problem is the 2.5 mm TRRS plug used. I was unable to find one of the corded adapters he used, but found a cheap $20 Rocketfish headset that included an adapter. On opening, it proved to be a one-piece plug adapter, but I was able to cut it apart into a separate 3.5 mm jack and 2.5 mm plug. The wires connecting the two were potted in a thermoplastic compound…softening it with heat let me strip much of the bulk off with pliers, prying and cutting with a razor knife did the rest. Given how much trouble it was to get ahold of the 2.5 mm plug, I made a single general-purpose adapter that I would be able to use with a variety of external triggers. I free-formed the adapter onto the plug using 4 resistors (a 15 kohm and 22 kohm in series for 37 kohm total, and a 3.3 kohm and 2.2 kohm) and a header socket, and encapsulated the whole thing in hot glue for a compact and solid adapter.
There’s easier ways to get the plugs, I was unlucky and in a hurry. To my surprise, Mouser does not seem to have these 2.5 mm plugs. DigiKey doesn’t seem to have them either, but does have cords with the required plugs:
Chop one of those in half, and for $6.09 you get two plugs with cords attached. Or you may just want to buy the jacks and use the cords whole…for some reason I’ve found the jacks much easier to find than the plugs.
Newark was the only place I found that actually has the plugs: