Buying from e-bay a common valve usually is not gravity feed.
Needs a lot of pressure in order to allow the water to flow when the coil is energized.
The tools that we are going to need in order to make this modification are :
A glue gun
A water bottle
A screw driver
A dremel with 1.7 mm drill bit
A 12V 1A AC to DC adapter / power supply
Time ago i bought the ATTEN TPR 3003T regulated power supply.
That device had constant voltage and constant current mode.
Offered voltage and current tuning by using two potentiometers a coarse one and a fine tune one.
It was a 30V / 3A general purpose power supply.
Recently i came across with Atten-APS-1502D. It was a voltage power supply (15V/2A) at a very attractive price.
I didn't spent further time and i bought that one too since i was a happy customer 🙂 .
When it arrived i noticed that the voltage selection would be really hard to set since it didn't offered a pair of coarse/fine tune potentiometers like the 3003T but only a global potentiometer.
I must admit that i didn't knew about that when i was buying it.
When i tested it, my thoughts become reality, since the voltage selection was way too hard to set.
The potentiometer was not only single turn but really small that make things even harder.
That was it ! I had bought the classic old school power supply without even knowing it ! 🙁
Here is some ideas of how to fix this fine tune problem...