I am attempting to build a water control system which allows proportional control of the water output flow.
I had initially thought of using servo-controlled ball valves, but it was suggested that solenoid valves can be modulated using PWM or similar input and thus end up with a somewhat variable flow rate.
However, I just tested a diaphragm/direct lift solenoid valve (like this one from ebay) using different input frequencies and duty cycles, and was unable to achieve anything other than a "full on" and "full off" condition.
Must I use a "direct acting" solenoid instead, in which the solenoid plunger directly controls the flow?
or does someone know if it's possible to modulate the diaphragm-type valves? If so, what frequencies and duty cycles would be most effective?
- Standard (US) municipal water source (50-100psi)
- 3/8" to 1/2" water supply line
- 12VDC (or less) input voltage, with minimal current draw (1A or less)
- Normally closed
- Low heat output - can stay open for extended periods (hours)
- very inexpensive - less than $10 each (preferably less than $5/ea)
Thanks for any insight! (Would this be a better question for the Engineering section?)