Forums

"Input" on an "output"

Started by Don Y September 15, 2013
Hi,

I've added four hose bibbs around the yard, each behind an
electric solenoid (24V).  The intent is for supplemental irrigation
for new plantings, etc.  (attach hose to hose bibb; run hose
out to be proximate to the new planting; "program" irrigation
system to dispense water via this particular "hose circuit"
for the several weeks required to get root system established)

I'd like to be able to *manually* signal the irrigation
system that I would like the electric valve engaged (and,
later, possibly disengaged!).  But, I don't really have a
spare conductor to dedicate to that purpose.  :<

So, I figure I could *share* the "solenoid drive" function with
the "button sense" function.

(remember, this is outdoors in the weather so I'm not keen on
putting any electronics out there that won't appreciate the
heat, cold, water, sun, etc.)

I figure I can wire a NO button across the valve solenoid (either
directly or with some series resistance).  Then, on the driving
side, sense this "short" when the solenoid is NOT energized (i.e.,
please turn ON the valve) as well as when it *is* energized (i.e.,
please turn OFF the valve).

[Similarly, I could add a NC button in series and "probe" the
load when off vs. on]

Any suggestions as to other issues that would make one of these
approaches better/worse than the other?  Off hand, the NC in
series seems like it would be more troublesome (i.e., if the
button failed, the valve is not usable).

Or, cleverer solutions?

(I'll have to characterize the valves - and hope any replacements
in the future are similar!)

Thx,
--don
On Sun, 15 Sep 2013 12:31:25 -0700, the renowned Don Y
<this@isnotme.com> wrote:

>Hi, > >I've added four hose bibbs around the yard, each behind an >electric solenoid (24V). The intent is for supplemental irrigation >for new plantings, etc. (attach hose to hose bibb; run hose >out to be proximate to the new planting; "program" irrigation >system to dispense water via this particular "hose circuit" >for the several weeks required to get root system established) > >I'd like to be able to *manually* signal the irrigation >system that I would like the electric valve engaged (and, >later, possibly disengaged!). But, I don't really have a >spare conductor to dedicate to that purpose. :< > >So, I figure I could *share* the "solenoid drive" function with >the "button sense" function. > >(remember, this is outdoors in the weather so I'm not keen on >putting any electronics out there that won't appreciate the >heat, cold, water, sun, etc.) > >I figure I can wire a NO button across the valve solenoid (either >directly or with some series resistance). Then, on the driving >side, sense this "short" when the solenoid is NOT energized (i.e., >please turn ON the valve) as well as when it *is* energized (i.e., >please turn OFF the valve). > >[Similarly, I could add a NC button in series and "probe" the >load when off vs. on] > >Any suggestions as to other issues that would make one of these >approaches better/worse than the other? Off hand, the NC in >series seems like it would be more troublesome (i.e., if the >button failed, the valve is not usable). > >Or, cleverer solutions? > >(I'll have to characterize the valves - and hope any replacements >in the future are similar!) > >Thx, >--don
The NC in series seems very straightforward. Just put 0.1mA or something like that through the loop and detect an open circuit. Add a time-out for instant indication of a broken switch or wire. No problem with different types of solenoids. The parallel version seems troublesome what with the possibility of pushing the switch when the solenoid is energized and and the relatively low resistance of the solenoid coil. You could probably do something cute taking advantage of the inductance of the coil, but do you want a project or a quick solution? Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
=20
> I figure I can wire a NO button across the valve solenoid (either > directly or with some series resistance). Then, on the driving > side, sense this "short" when the solenoid is NOT energized (i.e., > please turn ON the valve) as well as when it *is* energized (i.e., > please turn OFF the valve).
If you are talking about shorting the 24V supply line to signal it, you bet= ter have plenty of replacements ready. It might only work once, or not at = all.
> Or, cleverer solutions?
No, but cleaner solution: The proper way is to RF from a handheld controller back to the 24V source, = most likely inside your garage. This controller has numeric keypad. So, you can use "*1" to turn #1 on, "#= 1" to turn #1 off, etc. The controller on the right can control eight or m= ore relays. The problem is that you have to program it yourself. We only = supply you the tools to do it. You need to program both the base and remot= e controllers. http://173.224.223.62/rf/remote.jpg
On 9/15/2013 3:25 PM, edward.ming.lee@gmail.com wrote:
> >> I figure I can wire a NO button across the valve solenoid (either >> directly or with some series resistance). Then, on the driving >> side, sense this "short" when the solenoid is NOT energized (i.e., >> please turn ON the valve) as well as when it *is* energized (i.e., >> please turn OFF the valve). > > If you are talking about shorting the 24V supply line to signal it, > you better have plenty of replacements ready. It might only work > once, or not at all.
No, that would depend on what was "upstream" from the "short". E.g., if driven by a current limited source, the button just causes that limit to be engaged.
>> Or, cleverer solutions? > > No, but cleaner solution: > > The proper way is to RF from a handheld controller back to the 24V > source, most likely inside your garage. > > This controller has numeric keypad. So, you can use "*1" to turn #1 > on, "#1" to turn #1 off, etc. The controller on the right can control > eight or more relays. The problem is that you have to program it > yourself. We only supply you the tools to do it. You need to program > both the base and remote controllers.
Already have that (read post). Problem is it is not convenient. E.g., if you are in the yard and decide you want to use the hose to "fill a bucket", you'd have to run into the garage to "enable" the water at a particular "faucet" (bibb); then, back into the yard to manually open the (mechanical) valve on the faucet; etc. Much more convenient to push a button *at* the faucet (hose bibb), turn the manual valve on, dispense water and then reverse the process when done. (or, rely on an implicit timeout enforced by the irrigation controller)
> E.g., if you are in the yard and decide you want to use the > hose to "fill a bucket", you'd have to run into the garage to > "enable" the water at a particular "faucet" (bibb); then, back > into the yard to manually open the (mechanical) valve on the > faucet; etc. >
Don't you have electric valves already? I.e. 24V solenoid? Typical sprinkler valve work fine with pressurized water. You don't need to open or shut the water source.
On 9/15/2013 3:46 PM, edward.ming.lee@gmail.com wrote:
> >> E.g., if you are in the yard and decide you want to use the >> hose to "fill a bucket", you'd have to run into the garage to >> "enable" the water at a particular "faucet" (bibb); then, back >> into the yard to manually open the (mechanical) valve on the >> faucet; etc. > > Don't you have electric valves already? I.e. 24V solenoid?
Yes. They are upstream from the hose bibbs ("faucets"). They *gate* the flow to the hose bibb.
> Typical sprinkler valve work fine with pressurized water. You > don't need to open or shut the water source.
The manual valve ("faucet") is DOWNstream from the electric valve. It is used to set the *rate* of flow. Including "off", if need be. Do *you* always use a garden hose with the "faucet" wide open? Or, do you use the "faucet" to adjust the flow to a rate that is appropriate for *how* you are *using* the water? E.g., if I am washing the exterior windows, I don't need the water to be RUNNING for that entire time. Instead, I turn it on, wet down the windows, then turn it off while I soap them, etc. When they have been "washed" (soaped), I turn the water back on and rinse them clean. When all of the windows are done, I'll rinse out the soap bucket and then turn the water supply "off" for good. In this scenario, the "button" would be pushed exactly twice: once just before I started (wetting the windows) and once after I had finished rinsing the bucket.
> The manual valve ("faucet") is DOWNstream from the electric valve. > It is used to set the *rate* of flow. Including "off", if need be. >=20 > Do *you* always use a garden hose with the "faucet" wide open? > Or, do you use the "faucet" to adjust the flow to a rate that is > appropriate for *how* you are *using* the water?
=20 There should only be one valve. If you build the system properly, it will save lots of walking/running back= and forth. But you need something better than the dumb sprinkler controll= er in most garage. At the risk of disclosing too much information too early, someone we are wo= rking with is building an RF controlled electronics faucet. Namely, it can= adjust flow, rather than just on and off. That's why they need more intel= ligent controller at the source (garage), but more convenient remote (hand-= held) at the usage site (lawn and yard).
Hi SPehro,

On 9/15/2013 1:20 PM, Spehro Pefhany wrote:
> On Sun, 15 Sep 2013 12:31:25 -0700, the renowned Don Y > <this@isnotme.com> wrote:
>> I'd like to be able to *manually* signal the irrigation >> system that I would like the electric valve engaged (and, >> later, possibly disengaged!). But, I don't really have a >> spare conductor to dedicate to that purpose. :< >> >> So, I figure I could *share* the "solenoid drive" function with >> the "button sense" function.
In any scenario, if the button fails, I lose the ability to signal for water -- this is an acceptable loss.
> I figure I can wire a NO button across the valve solenoid (either >> directly or with some series resistance). Then, on the driving >> side, sense this "short" when the solenoid is NOT energized (i.e., >> please turn ON the valve) as well as when it *is* energized (i.e., >> please turn OFF the valve). >> >> [Similarly, I could add a NC button in series and "probe" the >> load when off vs. on] > > The NC in series seems very straightforward. Just put 0.1mA or > something like that through the loop and detect an open circuit. Add a > time-out for instant indication of a broken switch or wire. No problem > with different types of solenoids.
I'm leary of that approach as the button is now a reliability issue. If the button fails, then the function associated with the button should be the only thing that I "lose" (i.e., not being able to call for water on/off). If the button fails open, I can never activate the valve. Nor can I see if the valve is even present (vs. an opened coil, etc.). I.e., the "circuit" requires immediate attention.
> The parallel version seems troublesome what with the possibility of > pushing the switch when the solenoid is energized and and the > relatively low resistance of the solenoid coil. You could probably do > something cute taking advantage of the inductance of the coil, but do > you want a project or a quick solution?
I figure all I need to do is cause a "noticeable" increase in current drawn while the button is depressed. Then, be able to tell that the draw has increased (beyond what it was, previously) or is "at" some particular level (though this doesn't have to be precise). If the button fails open, I can still actuate the valve, detect the valve as present (not an opened coil, etc.). I can NOT detect that the button is broken, though! If the button fails closed, I can also continue to actuate the valve, detect an open coil, etc. I just waste more power in the process. And, I can be reasonably certain that an "always pressed" button is probably a defective button and not a user standing outside for "12" hours with his finger holding the button down! :> I.e., the circuit remains functional but degraded. Trick is ensuring the "difference" between no load (open coil), just button (open coil but button pressed), coil (engaged or idle) and coil with button are all discernible without having to adjust for some "future" coil characteristics. E.g., I think the coil on the master valve is considerably different than these satellite zones.
Hi Edward,

On 9/15/2013 5:10 PM, edward.ming.lee@gmail.com wrote:
> >> The manual valve ("faucet") is DOWNstream from the electric valve. >> It is used to set the *rate* of flow. Including "off", if need be. >> >> Do *you* always use a garden hose with the "faucet" wide open? >> Or, do you use the "faucet" to adjust the flow to a rate that is >> appropriate for *how* you are *using* the water? > > There should only be one valve.
No. You're assuming that one valve also does metering. That changes the requirements ($$) for the valve -- should the other 15 irrigation valves similarly be proportional actuators? Even though the individual *loads* they feed are already predetermined flow rates? Should you "stock" two different replacement valves because you won't know which type may fail from calcification, etc.? Will homeowner be able to buy that valve from a local supplier for $20? How do you connect hose to this "pipe", then? Look for a hose bibb that does NOT have a manual valve as part of that assembly? (!) Or, force that manual valve all the way open and then cut the knob off so it doesn't look like one was ever present? :> In our case, *two* valves must be engaged in order to dispense water: the master valve gates water into the outdoor plumbing (several manifolds around the yard each with one or more valve assemblies) while a secondary valve feeds a particular "circuit". This allows us to keep that outdoor plumbing unpressurized unless needed. And, ensures any water standing above soil level drains automatically to avoid frozen pipes (I've added "spitters" to the "load" side of each valve). Also complies with municipal code requirements for "backflow prevention" (so water from our yard isn't ever drawn *into* the municipal water supply). And, minimizes the chance of a (plastic!) valve failing and flooding the yard (as has happened to two of our neighbors at separate times). Lastly, ensures the water is gated OFF in the absence of power (each valve can be "manually" opened but that is tedious).
> If you build the system properly, it will save lots of walking/running > back and forth.
The only "build" decision that saves walking back and forth is having a means of calling for control action *at* the point where you are dispensing water. But, short of *forcing* the user to carry a "control", the only way to do this is to put the control in place without relying on the user to have it in his possession.
> But you need something better than the dumb sprinkler controller in > most garage.
Already have "better than" that. :> Yet, with "plain old irrigation valves". What's missing is a way of accommodating user without *burdening* him to have a control in his possession any time he *might* possibly want water (which could be any time he happens to be outside). E.g., you can purchase a smartphone interface for your irrigation controller. But, do you want to have to carry your phone so you can turn the water on? How do you make water available to the guy you've hired to paint your house -- give him your phone while you are away at work? :-/
On 15/09/2013 20:31, Don Y wrote:
> Hi, > > I've added four hose bibbs around the yard, each behind an > electric solenoid (24V). The intent is for supplemental irrigation > for new plantings, etc. (attach hose to hose bibb; run hose > out to be proximate to the new planting; "program" irrigation > system to dispense water via this particular "hose circuit" > for the several weeks required to get root system established) > > I'd like to be able to *manually* signal the irrigation > system that I would like the electric valve engaged (and, > later, possibly disengaged!). But, I don't really have a > spare conductor to dedicate to that purpose. :< > > So, I figure I could *share* the "solenoid drive" function with > the "button sense" function. > > (remember, this is outdoors in the weather so I'm not keen on > putting any electronics out there that won't appreciate the > heat, cold, water, sun, etc.) > > I figure I can wire a NO button across the valve solenoid (either > directly or with some series resistance). Then, on the driving > side, sense this "short" when the solenoid is NOT energized (i.e., > please turn ON the valve) as well as when it *is* energized (i.e., > please turn OFF the valve). > > [Similarly, I could add a NC button in series and "probe" the > load when off vs. on] > > Any suggestions as to other issues that would make one of these > approaches better/worse than the other? Off hand, the NC in > series seems like it would be more troublesome (i.e., if the > button failed, the valve is not usable). > > Or, cleverer solutions? > > (I'll have to characterize the valves - and hope any replacements > in the future are similar!) >
Is your pipework metal or plastic? If metal then you can use this as either as ground, or if plastic there might still be a small conduction path to ground depending on your water quality. You'll probably need a second voltage source and monitor current on this to determine if the button is pressed, keeping your solenoid power source isolated wrt earth. -- Mike Perkins Video Solutions Ltd www.videosolutions.ltd.uk