Besides adjusting the volume and concentration of solutions, controlling the duration of the dosing is a neat way to adjust how much is dosed. For larger tanks or dilute solutions, electronic timers with minute precision are usually precise enough. For smaller tanks, and concentrated liquids, shorter, adjustable dosing duration would be beneficial.
Also, it would be neat to find some electronics gadget that can be connected to the light timer, so that whenever the light turns on, fertilizers are dosed.
In my quest to find a solution I came across this little electronics kit
. I asked someone a specific question wrt suitability for my purposes, and they told me it would work. Unfortunately, this isn't the case.
The kit works by closing a power switch, and when opening it, it will time a couple of seconds and then interrupt power to the equipment that you want to control. Not too useful for this autodosing application.
To make this work, I would need some sort of relay switch that works with 110V, and switches between two pairs of contacts. When the lights are off (no power to relay), the switch of the MX046 would be closed, as displayed in the little picture. When the timer switch turns on, the relay would switch: open the MX046 switch, and turn on the pump, which then runs for the programmed number of seconds and turns off.
Any ideas what kind of relay I could use for that?
Better than a relay (which would draw constant power for long periods) would be some electronic flip flop switch that changes state each time power is applied. That would probably mean dosing every other day... not a problem though.
Anyway, any help, thoughts, comments that don't blow the budget (no X10 or Aquacontrollers) will be appreciated.