I am a film photographer and do some darkroom printing and always wanted one of the proper, advanced f-stop timers, but never really wanted to spend a couple hundred dollars on one. Eventually I figured my phone was already perfectly capable of doing the timing, it just needed a way to switch the enlarger.
So I built Darkplug around a cheap smart plug. The app controls the enlarger over the local network and does regular timing, f-stop timing, test strips, has an intuitive dodge/burn workflow, split grade (2 timing channels) and paper development timing.
I’ve been using it for a few months in my improvised bathroom darkroom.
Fair warning: the app was blindly vibe coded using Codex and Xcode.
arnarbi3 hours ago
Very cool. Is it controlling the plugs via direct Bluetooth connection? Or zigbee via a hub, or wifi (direct or via service)?
I always assumed, probably incorrectly, that there would be too much jitter in the actual timing so I had built a few prototypes of e.g. an esp8266 controlled relay, where you would give the MCU a duration rather than separate on/off commands. But I guess that was wildly over-optimizing. In your case, how stable is the delay from the app sending a command until the switch operates?
I'd add voice mode for color printing in total darkness.
jrflo2 hours ago
I was curious about timing accuracy too, has any testing been done on this? Is it accurate to 1s, 0.1s, 0.01s? How dependent is it on the smart switch hardware?
muhehe28 minutes ago
I played with development photos in a darkroom a long time ago. I don't think one second actually makes much difference.
sailingcodean hour ago
Good idea. I wonder if the iPhone's camera would be able to measure the projected negative and guide exposure time?