This past summer I dedicated some weeks to develop an Android app to serve as a digital f-stop timer using a Raspberry Pico W and a relay. It is called DisparaTimer, similar to the Spanish analog photography community Disparafilm which I am part of and that encouraged this project. It follows the trail of FADU timer, developed by a member of the British FADU forum around App Inventor (visual/blocks programming) and a hacked commercial WiFi switch (Sonoff Basic). Seems like a great app (never used it) but I was told that nowadays there are compatibility issues with FADU timer and there is no support or maintenance since 2021 when its developer abandoned the project leaving a GitHub repository. I opened the project in App Inventor getting several errors and a jigsaw of blocks for somebody not familiar with the development. So this was the trigger I was looking for to develop my first smartphone app, it is based also in low cost components but standard and open. In particular; Java in Android Studio for the app, and a WiFi switch built with a Rapsberry Pico W and a relay (electromechanical or solid state). There is no iOS version of the app and it never will from my side (99 USD/year fee among other "not friendly" Apple conditions). The total cost of the main components is below $20 and the app is totally free (no ads or any other monetization trick). My payment is everything I have learned during this trip which has been quite a lot.
After close to three months since the first publication in Play Store, 82 active installations, and no major issues reported, I think I can bring this timer to a wider audience. Perhaps someone else will find it useful.
After close to three months since the first publication in Play Store, 82 active installations, and no major issues reported, I think I can bring this timer to a wider audience. Perhaps someone else will find it useful.
Main features:
- Switch made of robust, affordable and widely available components.
- Switch easy to build with a basic knowledge of electricity.
- Exposure time from 0.1 to 999.9 seconds in 0.1 second minimum increments.
- Almost instantaneous response. No perceptible lags.
- Great accuracy. Measured error (via Photoplug) of 20 miliseconds in 1 second exposure time using an electromechanical relay (1.02 seconds for 1.0 seconds set time).
- Two working modes: TIMER and STRIP.
- TIMER: Traditional timer with up to 10 memories to store times, base time can be modified in preset f-stops.
- STRIP: Produces test strips using f-stops increments of up to ten steps. Three strip methods (AUTO, MANUAL, SINGLE) that control how each step is configured (incremental, full step time) and how it is the transition between steps (manual, automatic with a preset delay). The test trip can be transferred to the TIMER mode and select individual steps.
The app requires a smartphone with Android 9 or higher (works with Android 8 with some small interface issues). Screen sizes from 5 to 10'', optimum appearance normally from 5-7" with a minimum resolution of 1280x720 pixels.
The app can be downloaded here.
The user manual is here.
And the English site of the project for additional info (videos are in Spanish) below.
DisparaTimer, free f-stop timer — Disparafilm - Fotografía analógica en Español
DisparaTimer is a free app for Android phones that, when connected to a Raspberry Pico, can control your enlarger in the darkroom. A new, modern, and affordable f-stop timer.
There is also GitHub repository of the project published under GPLv3 license.
GitHub - visogonzalez/DisparaTimer: A f-stop timer for your enlager using an Android smartphone, a Raspberry Pico W, and a relay
A f-stop timer for your enlager using an Android smartphone, a Raspberry Pico W, and a relay - visogonzalez/DisparaTimer
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