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"Input" on an "output"

Started by Don Y September 15, 2013
Hi Mike,

On 9/15/2013 10:50 PM, Mike Perkins wrote:
> On 15/09/2013 20:31, Don Y wrote:
>> 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.
> Is your pipework metal or plastic?
For the purpose of your (below) comment, "PVC". Actually, the line *to* the solenoid valve is PVC while the line *from* the solenoid (to the hose bibb) is copper (for mechanical reasons). [I don't have deep enough pockets to run hundreds of feet of 1" class L copper *to* the solenoid valves :> And, I won't use galvanized under *any* conditions! Corrodes too quickly!]
> 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.
Note that there are 4 of these "faucets" that need to be individually "addressable" (i.e., 4 "demand" buttons as well). I figured I already have a common and a "drive" signal at each valve. So, if I can change the load that the driver "sees" (senses), then I can use this to convey information back to the driving end of the circuit. For example: - wire has been cut (a connection has failed, etc.) - circuit has been shorted - solenoid "open" (coil burned out) - solenoid "shorted" - solenoid intact, not actuated - solenoid intact, actuated - solenoid intact, not actuated, button pressed - solenoid intact, actuated, button pressed - etc. [the last four examples being the nominal cases, of course] Note that I can't test the button without having a user present. But, I can *probably* make many assumptions with little downside risk. E.g., if the button *appears* to be engaged for more than a handful of seconds, it's probably *broke* -- people aren't likely to push a button more than briefly... even if the system appears to be unresponsive, chances are they won't *lean* on the button indefinitely! (My design philosophy calls for alerting the user of problems as soon as you can realistically detect them; especially if you can do so *before* the user stumbles onto them and is, thus, inconvenienced!) Of course, all of this needs to be isolated from my actual controls (iso-optilators, etc.) to protect them from environmental conditions and "attack". So, whatever is on the "field" side of the isolation barrier wants to be robust and "sacrificial". OTOH, I *do* have "smarts" available and these are terribly low bandwidth signals.
On 15/09/13 21.31, Don Y wrote:
> Hi,
...
> Or, cleverer solutions? > > (I'll have to characterize the valves - and hope any replacements > in the future are similar!) > > Thx, > --don
Hi Don You could use DCC: DCC (Digital Command Control) - optionally with two-way-communication ! You could use HO-rails, 115/230V wire or coaxial cable to remote control and power e.g. an antenna rotor - with only two wires. Acually you could remote control more than 100 antenna rotors - or locomotives, lights, railroad switches, (hose) solenoids... DCC is an open standard: http://www.nmra.org/standards/sandrp/consist.html https://en.wikipedia.org/wiki/Digital_Command_Control There are a lot of DIY electronics for DCC: My MiniDCC&#2013266089; System Block Diagram [uses 16F628 2*16 char LCD display] http://home.cogeco.ca/~rpaisley4/MyDCC.html Now: http://www.minidcc.com/ Before: MiniDCC&#2013266089; - A Digital Command Control Do-It-Yourself Project!: http://www3.sympatico.ca/robert.cote/minidcc6.htm Quote: "... DCC MiniStation&#2013266089; ... The MiniStation&#2013266089; has been improved considerably but still uses the same PCB. The new 16F628 with twice the memory offers a pin for pin drop-in replacement for the orginal 16F84A. Now you can add 128 speed step, F1-F4 function control, auto-repeat keystroke and up to 123 step of combined route/turnout sequencing just by replacing the chip. Assembly code for the new chip is available free. A pre-programmed 16F628 is also available. Best of all, there is no price increase for the new chip! See the menu below for details on how to build your own. ... DCC MiniBooster&#2013266089; An efficient and simple to build DCC booster has been designed using the most recent MosFet integrated chip from National Semiconductor&#2013266094;. A double-sided PCB prepared by John Zajdler is also available (see Parts menu). Now you can control up to 4 trains simultaneously, over 120 turnouts and program all your decoders using any one of the 4 NMRA standards at a fraction of the cost of a commercial unit! ..." http://web.archive.org/web/20050408160609/http://www3.sympatico.ca/robert.cote/LinkPage1.htm http://web.archive.org/web/20040804072725/http://www3.sympatico.ca/robert.cote/minidcc6.htm Loco-decoder for M&#2013265924;rklin-Digital in DIY http://home.arcor.de/dr.koenig/digital/ewiking.htm http://web.archive.org/web/20010802055424/ourworld.compuserve.com/homepages/Phil_Grainger/digitalc.htm http://web.archive.org/web/20090803162613/http://geocities.com/OzDCC/sources.htm http://www.dmoz.org/Recreation/Models/Railroad/DCC/ - "Locomotive" "talk-back": Recommended Practice RP-9.3.2: http://www.nmra.org/standards/sandrp/pdf/S-9.3.2_2012_12_10.pdf (main: http://www.nmra.org/standards/sandrp/consist.html ) /Glenn
Hi Glenn,

On 9/16/2013 1:49 AM, Glenn wrote:
> On 15/09/13 21.31, Don Y wrote:
>> Or, cleverer solutions? >> >> (I'll have to characterize the valves - and hope any replacements >> in the future are similar!)
> You could use DCC: > > DCC (Digital Command Control) - optionally with two-way-communication ! > > You could use HO-rails, 115/230V wire or coaxial cable to remote control > and power e.g. an antenna rotor - with only two wires. > > Acually you could remote control more than 100 antenna rotors - or > locomotives, lights, railroad switches, (hose) solenoids... > > DCC is an open standard: > http://www.nmra.org/standards/sandrp/consist.html > > https://en.wikipedia.org/wiki/Digital_Command_Control
Ouch! This seems like overkill for the "one bit" I want to transmit. :< It also looks like it would require a bit of "smarts" on the button end of the link. Note that the button would be located in a rather hostile environment -- temperature, precipitation, etc. So, I am hesitant to put much of anything out there beyond the switch itself (e.g., resistor is probably a safe bet but a *cap* would have problems holding its value, etc.). [Even the switch is a bit of a challenge to locate suitable candidates that are easily mounted (in a chunk of concrete) and impervious to the elements...] But, these are excellent references! I will dl/bookmark them. Thanks! It looks like it might be a practical alternative if I redesign the controls to reside *at* the valves. I think the best scheme is a set of *tiny* valves and controls that can be deployed at individual plants from a single "water bus" -- instead of creating a small number of "water circuits"/zones that feed a large number of plants concurrently. This could also open the door for "local sensing" whereby the individual needs of the plants could be monitored. (all these "tiny valves" would still have to communicate with some central "supervisor" to ensure they don't overdraw the available water supply -- as well as telling them what criteria they should operate under) --don
On 2013-09-15, Don Y <this@isnotme.com> wrote:
> Hi, >
> 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. :<
you've atcually got one, it's called "ground"
> So, I figure I could *share* the "solenoid drive" function with > the "button sense" function.
yeah, that'd work too.
> (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.)
diodes are fairly rugged
> 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). > etc.
sounds tricky.
> [Similarly, I could add a NC button in series and "probe" the > load when off vs. on]
that one's probably slightly easier.
> 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).
only if it fails open, if it fails closed...
> Or, cleverer solutions? > > (I'll have to characterize the valves - and hope any replacements > in the future are similar!)
have you seen that video where that guy wires three switches and three lamps in series... -- &#9858;&#9859; 100% natural --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
On 2013-09-16, Don Y <this@isnotme.com> wrote:
> Hi Edward, >
> 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? (!)
That's called a "hose union", a fairly common plumbing fitting, probably even more common in domestic irrigation.
> 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? :-/
that one's too easy. -- &#9858;&#9859; 100% natural --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
Hi Jasen,

On 9/16/2013 4:59 AM, Jasen Betts wrote:
> On 2013-09-16, Don Y <this@isnotme.com> wrote: > >> 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? (!) > > That's called a "hose union", a fairly common plumbing fitting, probably > even more common in domestic irrigation.
Hose union is MGH x MGH. I.e., connect two *hoses* together. More common to find FGH x FGH (to allow the "male" ends of two hoses to be interconnected -- as the female end of one of them is probably terminated at a bibb, someplace!) That would require FGH fitting into which it would mate. More likely you would sweat a 3/4 FPT adapter and screw a 3/4 MPT x MGH nipple into it. [ISTM, you can't find an MGH sweat adapter hence the need for the FGH fitting. But, I can't imagine a FGH sweat adapter either! Therefore, the FPT adapter with the MPT x MGH nipple] When was the last time you saw a MGH connection sticking out of a wall that *didn't* have a (manual) valve attached to it? :> (IME, never -- unless it was the male end of a *hose* already mated to a traditional hose bibb)
On Mon, 16 Sep 2013 06:00:24 -0700, Don Y <this@isnotme.com> wrote:

>Hi Jasen, > >On 9/16/2013 4:59 AM, Jasen Betts wrote: >> On 2013-09-16, Don Y <this@isnotme.com> wrote: >> >>> 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? (!) >> >> That's called a "hose union", a fairly common plumbing fitting, probably >> even more common in domestic irrigation. > >Hose union is MGH x MGH. I.e., connect two *hoses* together. >More common to find FGH x FGH (to allow the "male" ends of >two hoses to be interconnected -- as the female end of one >of them is probably terminated at a bibb, someplace!) > >That would require FGH fitting into which it would mate. More likely >you would sweat a 3/4 FPT adapter and screw a 3/4 MPT x MGH nipple >into it. > >[ISTM, you can't find an MGH sweat adapter hence the need for >the FGH fitting. But, I can't imagine a FGH sweat adapter >either! Therefore, the FPT adapter with the MPT x MGH nipple] > >When was the last time you saw a MGH connection sticking out of >a wall that *didn't* have a (manual) valve attached to it? :> > >(IME, never -- unless it was the male end of a *hose* already >mated to a traditional hose bibb)
The joys of plumbing! My hose bib in the back yard started leaking. Got a new washer, turned off the water, and tried taking it apart. An hour later, I gave up! Can't get the stem out, looks like lime build up is so thick that it has made its own washer in there. So, it looks like it is time to replace the hose bib. Go into Home Depot, talk to gal there, and she gives me something called a sharkbite fitting. You just cut off the old sweated on hose bib and put it on and screw on a new hose bib. Sounds doable. Next day, turn off water and go to get to work. First, I compare the new fittings and the existing - not the same size! She gave me a 1/2" sharkbite, but OD of existing is 1". Turn water back on... Go back to Home Depot, looking for pipe with OD of 1". She doesn't know of anything like that. Brings in old guy (my age!) and he thinks about it, and figures it out. Plumber used 3/4" pipe and a 1/2" hose bib, but sweated a coupler across both. Coupler would be flush with stucco wall. So, now I have a torch and plumbing kit, a new 3/4" sweat to male thread, and a new 3/4" hose bib. So, now I have a new adventure - learning to sweat pipe! Any hints and suggestions? Pipe is painted white - do I need to remove paint first, or just burn it off with torch? How hard is it to sweat off a coupler like this? Any advice will be appreciated! Charlie
On Mon, 16 Sep 2013 12:19:21 -0700, Charlie E. <edmondson@ieee.org>
wrote:

> >So, now I have a new adventure - learning to sweat pipe! Any hints >and suggestions? Pipe is painted white - do I need to remove paint >first, or just burn it off with torch? How hard is it to sweat off a >coupler like this? Any advice will be appreciated!
Don't burn the house down would be my advice. Soldering copper pipe is really easy if the parts are fluxed and bright-clean or already tinned. It's about impossible if they're dirty or there is a slow drip of water. The trick I learned to deal with the latter is to stuff a plug of white bread (no crust) into the pipe. The bread dissolves later.
On 9/16/2013 12:39 AM, Don Y wrote:
> 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 --
I don't get why you have the electric valves. What are they for when your mechanical valve is right there? About your proposed approach with a current limited driver for the solenoids and a button to activate the current limit, I don't get the problem. The solenoid will draw some current, but it will be for a considerable time. The button will draw a current for a short time. The discriminator will be time, not current. The PSU will not need to limit the current as much as measure it. The button can have a simple resistor to set the button current draw. If a current change is seen that lasts for the right amount of time it is considered a button push. Currents for other time profiles will be considered the solenoid or a fault. It would even be possible to implement other commands with other time durations. 0.5 second press turns on/off this faucet, 3 second press turns off *all* faucets for example. What ever you are using for a controller would need to be programmable at an appropriate level to implement this. -- Rick
On Sun, 15 Sep 2013 12:31:25 -0700, 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
Some irrigations controllers are able to sense a shorted solenoid valve. RTFM, or momentarily short a valve and observe what shows on the display. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.