DC Water-Flow Switch Control

[Walt]

I have a solar pump with pressure tank and pressure switch that feeds the cabin. I have installed a 12 volt controlled 1 1/2" valve to fill the the water tank and need some guidance on building a control circuit for it.

The components for the system are: 1) 1 1/2" valve that is controlled by a 50mS 12 volt pulse to activate and deactivate, 2) a normally open float switch, 3) 12 volt solar system with batteries.

What the circuit needs to do: 1) when the float goes shorted a single 50mS 12volt pulse needs to be sent to the valve, 2) the trigger needs to have a 5 to 10 minute hold to allow the water level to stabilize, 3) when the tank is full and the float goes open the controller needs to send another 50mS 12 volt pulse to shut the valve off and again the trigger needs to have a 5 to 10 minute hold to allow the float to stabilize.

If any of you fine folks could get me headed in the right direction I would be very grateful.

Thanks,

Walt

[stephent]

Well, simplist way would be here http://www.uoguelph.ca/~antoon/gadgets/555/555.html

Little harder but nice to program timings. etc differently would be using one of these.

http://www.rev-ed.co.uk/picaxe/

[gizmo]

Sounds like a job for a PicAxe.

I used one to control a 12v pump on my header tank, story here.

http://www.thebackshed.com/Windmill/PumpControler.asp

Once you have used your first PicAxe you wont look back, the chips are only about $5 and easy to program with the free software.

Glenn

[jimjjnn]

use a hydronic heating valve. My heating sys uses 24 volt ac Valves. Dang, theres the bug "AC". Oh well don't know what system you are using.

[Walt]

Thanks for the replies. I just ordered the PicAxe Controller. When it gets here I will probably be asking more questions.

Thanks Again,

Walt

[Ungrounded Lightning Rod]

If it's a selonoid rather than something with electronics in it, DC is fine.

The "AC" means it's "shaded pole", i.e. the core is split near the gap and half of it has a D-shaped copper washer around it.  That is a shorted turn.  When the coil is fed with AC, its eddy currents cause the mag field to lag by a quarter cycle in the part of the coil that penetrates it.  That way half the core is always attracting the actuator and it doesn't buzz.

(Alternatively it might have a bridge rectifier or a pair of diodes, which will freewheel during the cycle-changes or the missing half-cycle and achieve the same effect.)

Feed it DC (and if it doesn't have diodes already be sure to use the usual kick-reducing diode or diode-resistor combo to protect your semiconductors) and it will work even better than it does with AC.

[Nando]

Walt:

Where are You located ?.

Your requirements calls for a different timer than the 555, A cmos divider with oscillating input that one can set for doing what you want.

The CMOS CD4060B 14 Stage Ripple-Carry Binary Counter/divider and Oscillator.

The oscillator is set to the pulse time that the valve controller needs, then it is divided by the 14 stages to reach the desired delay hold time.

It can operate from 12 volts and extremely low power.

The detector needs have a pulser to trigger a Flip-flop CD4013B that set the pulse then the CD4060 resets the CD4013 to stop the 50 millisecond pulse, then it continuous oscillating and not accepting more pulses from the switch ( though You need to think and detail why the 10 minutes, the tank may get full before the 10 minutes elapses).

The switch detector with bipolar direction needs to be formed using an exclusive Nor gate with a delay in one of the input pairs to produce the pulse triggering the CD4013B -- I do not have the Exclusive Nor part number at hand.

The 50 millisecond pulse needs to be buffered with a Power MosFet, protected with a power diode ( 1 amp or so) that is in reverse parallel with the valve controller.

Send a message to me, change anti-spam in the e-mail address.

Nando