This project started as a need for a photographic project of mine. I needed to make lot of overlaping exposures on a single print, with variables times. It would have been 80 single exposures, with time going from 3 to 15 minutes each. The whole process would have take more then 12 hours, staying beside the printing box.
So I picked up an Arduino mini I had lying around, a 7 segments clock display and its shift register salvaged from a TV decoder, a rotary encoder from a car audio system, and a few hours later I had already saved a lot of time!
Using it it clearly appeared that this board would have been usefull to me for many years, so I dive into designing one that could be used by photographers knowing nothing of electronics and programming, but in need of such a tool.
The main features of this board are:
- Arduino based design, running on Atmega 8.
- a large (48x18) 7 segments clock display driven by a MAX7219 chip.
- a rotary encoder to setup time.
- a large push button to start/pause/stop exposure (plus the trace on board for a second one if needed)
- a relay, for switching 12VDC led strips as well as 240VAC bulbs or tubes.
- a voltage regulator so it can be powered from led strip power unit, and
- a USB plug to power it from regular phone charger, when used with 240VAC.
- exposed pins for I2C, SPI, serial for further developpement or hacking.
The software do the following:
- set a time (!)
- start, pause, stop exposure.
- save some exposure times into persistant memory
- recall memory saved time.
The board is around 150x50x20mm, intended to be mounted inside a user-made UV box, as well as an existing one. It of course can be mouted also in a dedicated case if the user wants it!
There are screw connectors for power in and power switching on relay side, so there is no soldering needed when mouting it.