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#128621
..ecohouse as in economical and ecological

Hi folks,

I will need some small help from you to finish this project so bare with me! But the idea is great and simple!

I built a simple project based on this article (http://inhabitat.com/5-tips-to-green-yo ... m-joaquin/). As a first tip it mentions installing a foot pedal on one's sinks. It also gives links to comercial products.

But as I had all the necessaries, I decided I could build my own kitchen sink pedal.

The main ingredients are:

2pc 12V Solenoid Valve - 3/4" (http://www.sparkfun.com/products/10456)
1pc Foot Switch (http://www.seeedstudio.com/depot/foot-s ... th=156_160)
1pc 12V Adapter (http://www.sparkfun.com/products/9442)
1pc DC Barrel Power Jack/Connector (http://www.sparkfun.com/products/119)
1pc Toggle Switch (http://www.sparkfun.com/products/9276)

(I think the project is missing some capacitors or resistors - for smoothing the output of the adapter - plus other components)

You guessed it! I am not a EE guy! But I did manage to make the whole thing work smoothly until my adapter failed

So this is how it works!

A Solenoid Valve like the one we are going to use is normally closed. That means that as long as no current is passing through it, water will not be permitted to pass either! We have to take this into consideration when we do the plumbing because if the electricity fails for different reasons you would want to use your faucets even then!

From a plumber's point of view:

The cold water pipe is connected to a T fitting and then to the Solenoid Valve and then to a T fitting again finishing into the normal pipe that goes towards the faucet. The first T fitting has a manual valve connected to it at the 90 degree output and then it is connected to the other T fitting's 90degree input (in this case). The T fittings are put here for fail-safe reasons (in case the electrical part of the project does not work for different reasons as mentioned above). The Manual Valve is kept closed to force the water pressure towards the Solenoid Valve and is to be opened only if problems with the Solenoid Valve are to occur.

I tried to make a schematics to the whole plumbing . I added some points, otherwise all the spaces between the different characters would have been deleted once this was posted. Don't know why!
.....................................
..->T->SV->T->..........
.......|............^...............
.......v............|...............
.....MV ..........|...............
.......|.............|...............
.......L________J...............
.....................................

">", "v" and "^" stand for direction of water flow
"T" stands for T fitting
"SV" stands for Solenoid Valve
"MV" stands for Manual Valve
"L" and "J" stand for L fittings

From an electrician's point of view:

The Solenoid Valve doesn't seem to have a positive and a negative so you don't have to take care of that. So I connected one of the leads directly to the negative of the DC Barrel Power Jack/Connector. The other lead is connected to the foot pedal. The pedal I use has 3 leads (black, red and white). Two are for negative and positive, respectively and the third one is for signal (white). We want the pedal to act as a normally closed switch so we will use the positive and the signal leads. So whenever we step on it we connect the positive lead to the signal lead, thus letting current pass.

The toggle switch is present in cases where you would want to let the faucet run without you being present (as to keep the pedal pushed).

..................................................
..........12VDC ---- SV -----.......
........... |..............................|.......
........... |..............................|.......
............|..............................|.......
............L___toggle switch___J......
............|..............................|.......
............|..............................|.......
........... L_____pedal________J.......
...................................................


Warning: The adapter that I am using that is a 12VDC 900mA got burned and I suspect spikes in current while turning the installation on (pressing the pedal). And I believe the installation needs additional components like capacitors or resistors! Otherwise it works really nice

I hope this will installation is going to be used by many of you as it really helps you use less water while not trying to dramatically change your usual household habits. I consider it to be really cheap and in 2 or 3 months it could pay itself.

Please help me finish this project with what would be easy advices for many of you guys!
zws

PS: In the attached pic you can see (besides the hairy hand of the plumber that helped me ) that I also attached a Micro Hydro Generator and a Water Sensor but that is a whole different story!
You do not have the required permissions to view the files attached to this post.
#128641
One there are mechanical foot valves like this already (might find them more towards commercial installs) Just a thought. If I have a chance to look it over I'll see if there is anything I can think of with your project. In reality it probably is fairly simple and you want to try to make sure you don't get to complex.

Rich

Edit...
I just noticed the mechanical valve. You shouldn't need anything to smooth out the output of the power plug. It should be filtered enough internally and it isn't electronics you are powering just a simple electromechanical solenoid. It's a very basic on off setup. The switches should be parallel electrically to each other so that when either one is on the valve opens. You could split the positive wire to the toggle and the foot switch then feed them both to the solenoid with the ground going straight to the other side of the coil. Once you turn on either switch the valve opens and water flows. Even if both switches are on it won't hurt as it just becomes two paths for the same circuit.
If the adapter got burned you either have a bad adapter or a overdraw of current from it due to a short or the solenoid requires more current you could measure the amps going through the circuit with a multimeter or ammeter to make sure it isn't too much for the power source. You also might want to fuse it according on the dc side.


I can't think of anything special for it if you are just talking about the valving and control circuit. Throwing in the generator and anything else would then be decide by your intentions.
#128827
zws wrote:I tried to make a schematics to the whole plumbing . I added some points, otherwise all the spaces between the different characters would have been deleted once this was posted. Don't know why!
If you use the "Code" tags, you should be able to get your spacing to be reproduced
zws wrote:From an electrician's point of view:
The Solenoid Valve doesn't seem to have a positive and a negative so you don't have to take care of that. So I connected one of the leads directly to the negative of the DC Barrel Power Jack/Connector. The other lead is connected to the foot pedal. The pedal I use has 3 leads (black, red and white). Two are for negative and positive, respectively and the third one is for signal (white). We want the pedal to act as a normally closed switch so we will use the positive and the signal leads. So whenever we step on it we connect the positive lead to the signal lead, thus letting current pass.
You seem to be a bit confused about identifying terminals on a switch. It is very unlikely that your switch cares about positive and negative. It is much more likely that you have a common (C) (the one you're calling "signal"), a normally open (NO) (the one you're calling "positive"), and a normally closed (NC) (the one you're calling "negative"). As you want current to flow (and, thereby, water to flow) when you push the switch, you need to use the NO and C terminals. (If you use a normally closed switch, your solenoid valves would get current except when you pushed the pedal.)
zws wrote:Warning: The adapter that I am using that is a 12VDC 900mA got burned and I suspect spikes in current while turning the installation on (pressing the pedal). And I believe the installation needs additional components like capacitors or resistors! Otherwise it works really nice!
There is probably a current spike when you press the pedal and you can use capacitance across the power supply output to decrease that. However, my guess is that it was the spike when you turned off the solenoid valves (that is, released the pedal) that killed your power supply. When you turn on a DC inductive load (solenoid, relay, or motor, for example), the current creates an electromagnetic field. (This is a good thing, as that field is what opens the valve.) When you stop pushing electrons (that is, you open the switch), that field collapses. The collapsing field creates a reverse voltage spike. Even though you have disconnected one side of the solenoid from the power supply, there may be enough of an effect to damage the power supply. I suggest you search the SparkFun fora for "flyback" diodes and try that.

Given that you are using a power supply that's not much more than the reported current draw of the solenoid valves, it may be that your inrush current (current when you turn the solenoid valves on) requirement is more than your power supply can handle. However, you should be able to address that with either a larger power supply or some capacitance.

Good Luck,
Eric
#129298
Thanks guys!

I hope I solved the problem (meaning it won't give out again) by the doing the following:

I bought a 2A electronic adapter and I put a 1n4007 diode in reverse on the positive lead of the adapter, so it would take care of a spike when I turn off the solenoid valve.

Any thoughts on this are more than welcome!
zws
#129830
I've been working with a setup similar to this for almost two years now. I even sell a kit to help those of us who are less DIY knowledgeable put in a foot pedal faucet at http://green-tap.com. Feel free to take a look at how I set mine up in the install page.

Things I learned over the last few months:
- Try to use solenoids with metal threads. I started off with the exact solenoid valve you have in the picture. But because it has nylon threads, it's very easy to cross-thread.

- Do NOT leave the solenoid valve energized for extended periods of time (weeks, months, etc.). The solenoid coil heats up to around 150F and will "bake" the plastic parts and sooner than later you will have a leak. I used to include a switch in my kits, but took it out after I had some people experience leaks.

- If you want to be able to manually control the solenoid, you have a few choices. Build a "flow around" path that lets water go around the solenoid. Use a solenoid with a manual valve control (I found some on alibaba.com, but they are difficult to find). Use a latching solenoid. My next version of the GreenTap kit will be made with a latching solenoid that only requires a short pulse to open and another short pulse (in opposite polarity) to close. These can also be found on alibaba.com (ask for sample solenoids). I am using an arduino and an H bridge IC to control the latching solenoid. If you are interested in that project, email me and I can send you more details, including the sketch.

- I haven't had any problems with flyback, but I think that's because of the design of my foot pedal. I have had problems with all metal solenoids. Metal solenoids seem to have magnetic fields that are large and take a long time to collapse, meaning they stay on for almost a second after I take my foot off the pedal.

I am really surprised that foot pedal faucets are not more popular in the USA. They just seem so obvious. After having used one for a while, I have caught myself "looking" for the foot pedal at my friend's house.

You did a good job with your design. You'll have to let us all know if you're still using yours and if you like it.
#136045
Hey terex,

My foot pedal is working perfectly so I haven't checked this post since now.

Thank you so much for your advices!

And I already started looking into some of them! Latching solenoid, you say? It sounds they are really nice by your description! I am curious! I will contact you!

I am really surprised that foot pedal faucets are not more popular in the USA. They just seem so obvious. After having used one for a while, I have caught myself "looking" for the foot pedal at my friend's house.
Ahahaah! Same here!

All the best,
zws

PS: Great site, by the way!