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bdickens
01-21-2009, 12:41 AM
I'm hunting for a valve to control water flow via propeller. Ideally a 3v. No real "pressure" (water entering an aquarium, water draining). We have cobbled up a temp/water level and salinity, monitor, now we want to add the automated water change. Anyone got a recommendation on a good (cheap) electronically controlled valve ?

Thanks

Leon
01-21-2009, 01:09 AM
RS has this pinch valve:

uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0488756 (http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0488756)

You won't find any that operate from 3V.

Leon

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Bob Lawrence (VE1RLL)
01-21-2009, 01:11 AM
Have a look at this:

3-6VDC Electric Water Pump 6Ft Distance

Manufacturer: Generic Other Products
Sales Price $4.74

www.electronicsurplus.com/ccp71429-3-6vdc-electric-water-pump-6ft-distance-6-310-3661.htm (http://www.electronicsurplus.com/ccp71429-3-6vdc-electric-water-pump-6ft-distance-6-310-3661.htm)

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Aka: CosmicBob

kwinn
01-21-2009, 03:46 AM
I am pretty sure you will not find a valve that operates at 3.3V, and a prop pin certainly will not be able to provide the required current even if one existed. Use an opto isolator or solid state relay instead (which a prop pin can drive directly) and a washing machine valve.

Fred Hawkins
01-21-2009, 04:35 AM
Maybe there's something in drip irrigation that would serve. But cheap there is <$15 and on ebay, like this. ( http://cgi.ebay.com/Rainbird-3-4-Low-Flow-Valve-for-Drip-Irrigation_W0QQitemZ250355034328QQihZ015QQcategory Z20542QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153 .l1262)

Hope you do make it failsafe. It would be painful to pour out all the water and not refill it in time. Or to automatically fill your living room too.

dbpage
01-27-2009, 07:29 AM
I use mcmaster.com model 7877K3 12VDC ($24.80) solenoid valves to control water flow.· The Propeller drives it through·an Parallax ULN2803 Darlington Array ($1.50).· You can also use a 2N3906 transistor ($0.30) with a diode across the coil to clip back emf.

For variable control, I gang Parallax servos to needle valves.· See http://pageradio.com/fountain/index_1.html

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