I have previously used two electronise 4x relay switches on my boat, but now have developed an Arduino sketch to power one of their excellent 8x relay systems to do exactly what I used to have for a third the price. Not only that but have been able to write a diving and surfacing routine that responds to a ‘double tap’ of the transmitter.
What I want to do now is make my own depth keeping system. I have an old subtech ADC1 which has died. I dug the old sensor out of it and it is an MPX5100ap. I have attached that to the Arduino and it only measures pressure less that 1 bar. Ie it is at maximum at with air pressure. Ie only works when I suck, which is most of the time.. Now there must be some trick to this, or else there may be another sensor I can use.
The first thing I want to do is make a simple piece of code that starts the water pump when the boat breaches the surface, so a pressure sensor good enough for that would be great. Secondly to also to maintain a depth. If the MPX5100ap simply worked in reverse it would be all I need.