IanJ
28-Aug-2015, 12:06
I thought you all might be interested in a project I have underway.
First of all, I am an occasional 5x7 shooter, though I do not love the process of doing tray development. I had been using a Taylor 10-key timer, like this:
http://www.amazon.com/Taylor-Precision-Products-5820-10-Key/dp/B0007NIIPO
Which was cool, until a hair-thin wire broke, and I didn't feel like doing the micro-surgery necessary to repair it; I went back to my ancient GE wind-up X-ray timer and counting "one-one-thousand" to myself. That inspired me to make my own timer, which I call the Darktimer, as an open-source project. (Open source in this case meaning you can download the source code, and I'll be producing a wiring diagram and enough information to build one yourself for about $40 in parts.)
The Darktimer is, as its name suggests, aimed specifically at darkroom processing. It has no lights on it, so is suitable for use with open trays. It has one Big Red Button (and some smaller buttons for setting up timers), and can be easily programmed with a series of timers which will run sequentially, requiring just pressing the BRB each time. So I, for instance, would program it with a 60 second timer (prewash), an 8:30 timer (development), a 30 second timer (stop), a 2 minute timer (fixer, obviously variable depending on the state of the fixer), a 10 minute timer for final water wash, and then 30 seconds for rinsing agent. Press the BRB once to start the prewash timer. Press again to start the development timer, and so on. No complex interaction required in the dark.
Each timer beeps once per second, so you know it's going. Each timer has a setting you can change (per timer), which will do a double-beep every N seconds (think agitation reminder), and a longer beep every minute. The final five seconds have higher-pitched triple beeps before the final "you're done" sound, to give you some time to get film and stop bath together at exactly the right instant.
The whole thing is built out of an Arduino board, a little LCD screen, four pushbuttons, one power switch, a speaker, and a battery pack. Construction is pretty simple -- maybe not first-project simple, but pretty simple -- and building the circuit would take maybe a couple hours at most. Honestly, the Arduino is vastly overpowered for this project, but it's cheap and easy to use.
I've got my prototype to the point that it does (almost) everything it should, and I've got materials in hand to turn it into a finished-enough product. If there's any interest here, I'll post a link to the project page once I have it up, which will contain all the information you need to build one yourself. I'm open to questions, and if you have feedback, I'm interested in hearing it, though it probably won't get rolled into this first version, since I'm almost done.
First of all, I am an occasional 5x7 shooter, though I do not love the process of doing tray development. I had been using a Taylor 10-key timer, like this:
http://www.amazon.com/Taylor-Precision-Products-5820-10-Key/dp/B0007NIIPO
Which was cool, until a hair-thin wire broke, and I didn't feel like doing the micro-surgery necessary to repair it; I went back to my ancient GE wind-up X-ray timer and counting "one-one-thousand" to myself. That inspired me to make my own timer, which I call the Darktimer, as an open-source project. (Open source in this case meaning you can download the source code, and I'll be producing a wiring diagram and enough information to build one yourself for about $40 in parts.)
The Darktimer is, as its name suggests, aimed specifically at darkroom processing. It has no lights on it, so is suitable for use with open trays. It has one Big Red Button (and some smaller buttons for setting up timers), and can be easily programmed with a series of timers which will run sequentially, requiring just pressing the BRB each time. So I, for instance, would program it with a 60 second timer (prewash), an 8:30 timer (development), a 30 second timer (stop), a 2 minute timer (fixer, obviously variable depending on the state of the fixer), a 10 minute timer for final water wash, and then 30 seconds for rinsing agent. Press the BRB once to start the prewash timer. Press again to start the development timer, and so on. No complex interaction required in the dark.
Each timer beeps once per second, so you know it's going. Each timer has a setting you can change (per timer), which will do a double-beep every N seconds (think agitation reminder), and a longer beep every minute. The final five seconds have higher-pitched triple beeps before the final "you're done" sound, to give you some time to get film and stop bath together at exactly the right instant.
The whole thing is built out of an Arduino board, a little LCD screen, four pushbuttons, one power switch, a speaker, and a battery pack. Construction is pretty simple -- maybe not first-project simple, but pretty simple -- and building the circuit would take maybe a couple hours at most. Honestly, the Arduino is vastly overpowered for this project, but it's cheap and easy to use.
I've got my prototype to the point that it does (almost) everything it should, and I've got materials in hand to turn it into a finished-enough product. If there's any interest here, I'll post a link to the project page once I have it up, which will contain all the information you need to build one yourself. I'm open to questions, and if you have feedback, I'm interested in hearing it, though it probably won't get rolled into this first version, since I'm almost done.