I've modified one of these to be controlled by an Arduinohttp://www.arduino.cc/
, bypassing the salinity(conductance) tests and timer, but utilizing the relays and fuses on the board. I've tried a couple of different control sets, to mimic what other SWG makers use. One was a percentage setting - where it operates for a set percentage(10,20,30,etc..) of a set time period(15 minutes, 30 miutes,etc..) and reverses after another set time period(2 hours, 4 hours,etc..) Another delayed for a set time, then ran for a set time, reversing at a set time. I have a pump timer that I like, and seems pretty reliable, so I use that to power on the SWG with the pump. I like the delay after starting, it gives the water a chance to mix, and me to get a sample, before the chlorine production starts.
I originally wanted to unsolder the Sonix mcu, and put a socket in its place, so that I could use the Arduino to program a chip and stick it in the socket, but I ran into a lack of ability. I also needed it done quickly, so I just used the parts of the board that I could decipher, and isolated the rest by cutting/removing components/traces. If you don't want to use an Arduino, you can just control the relays with inexpensive timers. I found the Arduino fun to play with.
Here is what I found for the relay control: K1 connects the rectifier output(24 VDC) to the NC terminals of relays K2 & K3, and the 5VDC control power too. The relays are switched by grounding them after K1 has supplied them with power. When K2 & K3 are NC, the cell is idle(has no power), Leaving K2 NC and switching K3 puts positive power to the cell, switching K2 and leaving K3 NC puts reverse power to the cell. The fuses are built in between the relay outputs and the terminal strip where the rectifier and cell connect.
The Green LED will come on with the cell. I wanted to use the two buttons and two 7 segment LEDs for the programming UI(User Interface), but I've found that it isn't necessary to alter the settings much, and when I do, I just plug my laptop into the Arduino via USB cord sticking out of the bottom. The unit looks just like a "stock" one, except when its running, only the green LED is on, the red 7 segment counter LEDs are not on and pushing the buttons doesn't do anything. There are also no error alarms, and I won't know if the fuses are blown until after the fact,
When I get more time/motivation I would like to incorporate a power monitor that will alarm (bleep/flash LEDs) when set-points are reached (I don't know what the set-points even are!)