How can 20 people give thumbs down when he kindly educates in-depth electronic and mechanical information. Great info as I’ve just bought this exact type of timer for my allotment.
WATER BUTT USERS NOTE> Thank you Julian for the time taken in this fantastic video. I'd like to add the most recent version of this product is not really suitable for use on a water butt as they designed a new more powerful spring and there is too little water pressure to make it work. HOWEVER, if you have the newer larger diameter thicker spring swap it out. I ordered a replacement spring from China, Wire Dia 0.3mm x Outer Dia 6mm x Length 20mm. It now works very well on my water butt, not quite as good as the motorised timers but acceptable.
Excellent tear down and explanation. The human mind never ceases to amaze me. I would not have been able to come up with this design if I had taken a million years to think about it.
Thoroughly enjoyed the way you visibly loved to explore it all and discover what lies beneath the cover and how it all works with a curiosity of a little child and understanding of an informed adult. Kudos!
Thank you so much. Before buying this I was curious to see how inexpensive device like this do this. In your clear explanation I've not only learned it's operation, but also leaned the how solenoid work. Now I know how my toilet cistern diaphragm works. Thanks a lot!
Yes really. I made my guess before he took it apart and I was more or less close, but I didn't think of doing a passive diaphragm. This is way simpler than what I had.
good video Julian, glad you took it apart after you showed it a few weeks ago on your channel. I want to make something like this controlled by an arduino some day :)
Fascinating valve mechanism! Never seen that before :D Looks like something you could so easily control with home automation, being only a small DC motor
yes, please hack and mod this with your NRF thing, to control the timing & on/off from room. and you wont have to screw out that plastic cap every time anymore.
I think you may have missed out the fundamental point about how this kind of valve works. The back chamber has a larger area acting on the diaphragm than the valve inlet, so in equilibrium the force pushing the diaphragm onto the valve seat will always be greater than the force trying to open it. They're used all over the place, in toilet cistern fill valves, washing machines inlets and so on.
I hard wired one of these into a mister systems. Amazon sells a AAA battery adapter kit that includes a power supply. I ran the power cable of the back side/bottom of the plastic housing and sealed the cable hole with waterproof epoxy. Works perfectly!! And out of the sun.
interesting, a gear and cam operated pilot valve. It has the possibility of a stuck on failure mode when power dies though, which isnt exactly optimal.
That's really cool. I'm wanting to do a 6 channel irrigation arduino project. These valves seem that they would be awesome. I was surprised I couldn't find any ebay versions. Just wanting the guts so I can build my own controller.
Many flow control valves in various industries - including refrigeration and petroleum - employ this design of leveraging a small pilot force to control larger fluid forces and flows. Imagine many of these 'garden' controls are sold to cannabis growers. I enjoyed the vid.
Hi Julian, I have one of these units and I'm interested in using NiHM batteries and a small solar cell to trickle charge them. Could you please consider a video on the best way to set this up? I don't have any experience with solar but I am into RC hobbies so I'm OK with soldering, etc. Thanks for your very informative videos.
Nice mechanism. I did a bit of googling and only found solenoids that open when power is applied; this design only used power to change from open to close or v.v. very clever
14:01 Wow, so the water analogy works again for electronics. This is basically a transistor! You input a small current from the high impedance base and it causes the collector to 'open' and both flow out the emitter.
A great explanation of how these kinds of valves work is available on the washing machine episode of the Brittish TV series "The Secret Life of Machines." It's a fantastic series.
+Julian Ilett: The important thing to remember with valves like this, and the reason the water pressure closes, and doesn't open the valve, is that the surface area of the diaphragm is larger in the pressure area place stuff.
I purchased two Melnor aqua timers and both malfunctioned on the second year. The problem is that apparently the valve is not opening. What could be the problem? Could there be hard water deposits? Could the spring have broken? Could the solenoid have a loose contact? I really want to fix these timers, but I’ve yet to take them appart. Your video has been hugely useful, thanks a lot from Mexico.
You should be able to stop the leak from the brass adaptor by using PTFE tape. You could also remove the gland nut from its seat and wrap some around the tap spindle then, using the gland nut to push the tape down the spindle, re-tighten the gland nut to stop the leak from the tap without making the tap impossible to operate.
Julian: Twice you talked about "accumulated pressure in the back chamber". I think that when the needle closes the channel the pressure on both sides of the diaphragm is the same. What closes the valve is the spring. When the water is let through the small channel the pressure in front of the diaphragm is larger than behind and now the front pressure of the water opens it.
Gaston Groisman yes! Even though this is an old video I was going to make the same comment but checked to see if someone had already made the same comment. And you have :) It really doesn’t matter how weak the spring is, it just has to apply *some* force (even tiny tiny) to mean the closing of the valve. For me, it’s that which is the genius of this invention from 1910 or whatever. Interesting video, Julian
One more detail, the surface area on the back of the valve is larger than the front, and thus even at the same psi there is more force holding it closed, venting the back pressure permits it to open of course.
This is the standard way that water pressure valves have worked for decades. They use the water pressure itself to operate the valve that controls the water pressure.
What are your thoughts about wiring a panel mount on/off switch to this? I'd like to be able to turn it on and off without having to screw off the front plate. They sell water proof panel mount switches. It's going to be used for a mister system so the auto settings will only be used for when we want to run the misters on a hot day. It would be nice if I could just turn the dials to a setting, screw on the front plate, and only have to hit the button when using.
I have to say, as I only started fiddling with electronics a few months ago, mechanics are vastly more evolved than electronics. In analogs it is almost without limits, whereas electronics is like building with blocks. Quite strange really, as electronics aren't exactly a new thing. I wonder if the quest for speed and going the digital route is holding us back. It seems easier (cheaper?) to convert to digital going through a microcontroller and then back to analog than it is to make a discrete analog device, even for the simplest task. Also it's rather amusing to watch Mr. Ilett and Mr. Carlson go on about the mechanics in length, while the electronics is so obvious to them it's barely mentioned. Mr. Jones and especially Mr. BigClive doesn't seem to dwell so much on the position of screws.
Mine too. The supplied diaphragm was shit and was split within 6 months, leaving the cistern empty as it wouldn't hold back-pressure. Suffice to say when the guy from the housing came to repair it I blagged a few of them for spares.
A lot of valves for in-ground yard/garden sprinkler systems work on the same principal,but use a solenoid instead of a motor/cam/plunger. Also of note,they're commonly rated 24Vac,but I've found that they will often function from a 9V battery,or similar.
This is a no power needed on version then. those solenoids would have an armature electromagnetically held back from a spring. i thought a solenoid generally referred to a springed electromagnetic operated armature (used in other things like door locks and relays)
A very entertaining presentation. One wonders if there is an electrical/electronic analog for how the solenoid valve works. Though the problem of mains electric (the equivalent of mains pressure water) with delicate electronics (the equivalent of those tiny vents) would be problematic.
Hi Julian, I was thinking along the lines of an equilibrium valve as per we can find in a float operated cistern valve, but are there not similarities to the gas valves operated by, for example, a thermocouple? Very neat anyway.please include a subset of plumbing investigations, but I will sub anyway. I am captured. Muchas gracias desde el chico electricista en el distrito de lagos, inglaterra.
I share your enthusiasm for this water timer. It’s a pity it won’t work on gravity fed systems. Do you think increasing the spring strength and/or coating the diaphragm in vaseline would work? Graham .
Is there a way to modify this timer to change frequency from hours to minutes and water time to seconds instead of minutes? Or just make a new circuit instead?
This is also the way a gas pressure valve works only its all mechanical. The gas tank on my roof reads the psi in the storage tank which is periodically filled when I pay for more. From that is a pressure regulator with this device. It has an adjustment screw which varies the amount of tension on the diaphragm thus providing a very small movement regulating a much higher tank pressure. No matter how low (or high )the pressure is in the tank, within reason, the gas pressure to my stove remain adjustable from the diaphragm. Of course, the whole thing is sealed shut and made repairable by the manufacturer to protect us from ourselves.
one small correction in the closed position the spring is what holds the diaphragm closed because the water on both sides of the diaphragm has the same pressure
Well. There's also the difference in area on the diaphragm. The incoming water can only push on the center of the diaphragm. The water in the chamber pushes on the whole diaphragm. The pressure is the same on both sides, but not the total force on the diaphragm is not.
Hello Julian, If I got it right you said there is no endpoint sensors on the motor, what happens if power is removed during the travel of the piston? will the water pressure push the rest? Regards Stefan
So, I have a silimar modela to this one, just it's a digital one from Aqualin. It worked just fine for 6 months, and then I noticed that my water tank was going low too fast, and I realized that the timer valve was leaking. It was not leaking to the outside, but it was leaving a little water pass by even when in closed position. Any idea how can I fix it?
Hi Julian I have a 6 of these and they all have the same kind of issue (they require mains water pressure to work) i have two water barrels connected together and am only getting a dribble at the output.there is a fair amount of pressure from the 400 liters . Ive tried to remove the spring, cut the spring in half, drill a larger hole in the solenoid end. (am now about to drill a larger hole in the diaphragm end as well. ) (and also going to replace the tap on the barrel with a larger diameter tap .) in your wisdom which of these or an other idea would allow full flow with little pressure.
Hi Julian, nice educative video. Do you know what is the lowest pressure this would work on. I want to use it from a rainwater barrel, maybe 1 meter from the ground. Thanks in advance.
On a more serious note. Yeah it's clever how they use the motor driven plunger in place of an actual solenoid in this arrangement. Has a huge advantage when running off a couple of batteries in that it does not need be constantly energised to keep the valve open. I reckon those extra transistors are to do some kind of voltage level shifting and/or inversion to make the H bridge work.
Very interesting. I bought a very similar item from Amazon for £12, but it doesnt work in the same way. Mine uses a ball valve in which a motor turns the ball 90 degrees each time you activate the switch or timer. It seems its a lot simpler method but not sure which is best.
The ball valve is better imo, the control electrinics are simpler, it's mechanically simpler, it doesn't require a minimum inlet pressure and it doesn't clog as easily. The other one is more clever though
Kind of like a mechanical transistor. A small flow of water controls a larger flow of water. My lawn sprinkler system vales work this way. I was very impressed with the design once I figured it out. I believe it uses mechanical hydraulic advantage to move the diaphragm. The chamber on the back of the diaphragm has a larger surface area so the tap water pressure pushes harder on the diaphragm (more pounds per square inch) to close it against the incoming tap water pressure. Very ingenious.
Is there a way that i can use this kind of timer to make a automatic dog feeder...where I can connect this to a tub full of dog pellets and use it while we are out on vacation? suggestions please......
I love how the simplest everyday objects actually have some truly ingenious engineering within them. I take way too much for granted!
How can 20 people give thumbs down when he kindly educates in-depth electronic and mechanical information. Great info as I’ve just bought this exact type of timer for my allotment.
WATER BUTT USERS NOTE> Thank you Julian for the time taken in this fantastic video. I'd like to add the most recent version of this product is not really suitable for use on a water butt as they designed a new more powerful spring and there is too little water pressure to make it work. HOWEVER, if you have the newer larger diameter thicker spring swap it out. I ordered a replacement spring from China, Wire Dia 0.3mm x Outer Dia 6mm x Length 20mm. It now works very well on my water butt, not quite as good as the motorised timers but acceptable.
Excellent tear down and explanation. The human mind never ceases to amaze me. I would not have been able to come up with this design if I had taken a million years to think about it.
I shouted 'spring" at the computer when you did not put it back.
It's a very clever solution that uses the water pressure to do the heavy lifting
Two great videos this week Julian!
Thanks for the laughs!
That, good Sir, was absolutely fascinating! Big thank you for your videos from Bavaria!
Thoroughly enjoyed the way you visibly loved to explore it all and discover what lies beneath the cover and how it all works with a curiosity of a little child and understanding of an informed adult. Kudos!
One of your best videos! Never thought about how these valves work. Great info! :)
Enjoyable tear down videos. Thanks for the efforts.
Thank you so much. Before buying this I was curious to see how inexpensive device like this do this. In your clear explanation I've not only learned it's operation, but also leaned the how solenoid work. Now I know how my toilet cistern diaphragm works. Thanks a lot!
Wonderful! Thank you! Saw it at a lower price than other timers and was hesitant to buy. Now that I see the design I will buy one.
great teardown Julian, that valve is awesome, nice one.
Entirely wizard grade piece of engineering that. I love how it makes the water pressure to all the heavy lifting! Thanks for the post.
Excellent valve system vlog, delivered with panache. Nice to hear timeless enthusiasm of discovery. I must do H-bridge breadboard project now!
Very good, I really enjoyed this teardown.
Another great teardown. Learned a lot, that is a fascinating device.
a very lucid explanation and reverse engineering of the electronic faucet, thank you
Nice, keep up the good teardowns
I gotta get me a few of those for my garden. Good deal. Good review. Thanks Julian.
That trick to prevent cross threading is awesome! I've never heard of that one before.
Great video! I was able to open and fix mine thanks to your detailed explanation of the system.
what was the problem?
Nice informative video. I was wondering how a water timer works and this resolves my questions exactly.
OMG I use your method of preventing cross threading screws all the time! its really useful!!
Awesome!!! Really interesting seeing how that works!
Very good explanation. Thanks a lot!
Great video. Thanks for this!
I'm amazed. Nice video! Very good indeed!
that valve was awfully clever. I am in awe
Yes really. I made my guess before he took it apart and I was more or less close, but I didn't think of doing a passive diaphragm. This is way simpler than what I had.
Very good educational video.. I liked the narration a lot. Nice explanation too
Very nice! Thank you for explanation of this wonderful principle. I like water physics as well as electronics :)
I enjoyed this video. Thanks.
An old video but it gave me confidence to pull apart a Holman timer which enabled me to get it working again (jammed cogs). Thanks Julian.
good video Julian, glad you took it apart after you showed it a few weeks ago on your channel. I want to make something like this controlled by an arduino some day :)
excellent examination!
another great vid, keep them coming :)
Very well explained and without superfluous details
Fascinating valve mechanism! Never seen that before :D
Looks like something you could so easily control with home automation, being only a small DC motor
Yes, a wireless module would fit easily inside the case of this thing :)
yes, please hack and mod this with your NRF thing, to control the timing & on/off from room.
and you wont have to screw out that plastic cap every time anymore.
Learn something every day. Nice mechanical amplifier. Fascinating indeed. Seems a copy of Gardina. Thanks for keeping us entertained.
fascinating. Just bought one. Nice to know what going on in there.
The valve is really cool, reminds me of a transistor
I wonder if you could make a full-adder using water valves.
+Cory Marshall The term you're looking for is "fluidics": en.wikipedia.org/wiki/Fluidics
Thank you. You saved me 30 bucks!
I think you may have missed out the fundamental point about how this kind of valve works. The back chamber has a larger area acting on the diaphragm than the valve inlet, so in equilibrium the force pushing the diaphragm onto the valve seat will always be greater than the force trying to open it.
They're used all over the place, in toilet cistern fill valves, washing machines inlets and so on.
Your the man, this helped me a lot, my timer does not go to pipe, it goes on barel, so I had to find a way to make it opens on weaker pressure, thanks
Awesome, thanks!
I hard wired one of these into a mister systems. Amazon sells a AAA battery adapter kit that includes a power supply. I ran the power cable of the back side/bottom of the plastic housing and sealed the cable hole with waterproof epoxy. Works perfectly!! And out of the sun.
interesting, a gear and cam operated pilot valve. It has the possibility of a stuck on failure mode when power dies though, which isnt exactly optimal.
That's really cool.
I'm wanting to do a 6 channel irrigation arduino project. These valves seem that they would be awesome. I was surprised I couldn't find any ebay versions. Just wanting the guts so I can build my own controller.
When removing plastic labels, a hot air gun is your friend. 😉
A quick blast at 100C or so softens the glue nicely, enabling easy-peel action. 👍
After seeing your video I bought the same one with the Idea to fit a microcontroller into it...
Many flow control valves in various industries - including refrigeration and petroleum - employ this design of leveraging a small pilot force to control larger fluid forces and flows. Imagine many of these 'garden' controls are sold to cannabis growers. I enjoyed the vid.
fascinating!!!
Thanks for the video, I have one and it was leaking had now idea how to open it up. My one had one screw at the top under the sticker.
Hi Julian, I have one of these units and I'm interested in using NiHM batteries and a small solar cell to trickle charge them. Could you please consider a video on the best way to set this up? I don't have any experience with solar but I am into RC hobbies so I'm OK with soldering, etc. Thanks for your very informative videos.
Nice mechanism. I did a bit of googling and only found solenoids that open when power is applied; this design only used power to change from open to close or v.v. very clever
Soooo. It's a piston valve that has the pressure release runoff directed in to the output. Very nice. This one gets a bookmark for sure.
I have the solar powered model. Very nice video
Nice video full of information, thus this device applicable on low pressured running water?
14:01 Wow, so the water analogy works again for electronics. This is basically a transistor! You input a small current from the high impedance base and it causes the collector to 'open' and both flow out the emitter.
Pneumatic valves are very similar, with a little valve controlling a beefy valve.
A great explanation of how these kinds of valves work is available on the washing machine episode of the Brittish TV series "The Secret Life of Machines." It's a fantastic series.
Very clever
Hi @Julian ilett .. do you have an idea what will happen if you are on holiday and using this timer at home for irrigation
and the battery is low?
+Julian Ilett: The important thing to remember with valves like this, and the reason the water pressure closes, and doesn't open the valve, is that the surface area of the diaphragm is larger in the pressure area place stuff.
I purchased two Melnor aqua timers and both malfunctioned on the second year. The problem is that apparently the valve is not opening. What could be the problem? Could there be hard water deposits? Could the spring have broken? Could the solenoid have a loose contact? I really want to fix these timers, but I’ve yet to take them appart. Your video has been hugely useful, thanks a lot from Mexico.
You should be able to stop the leak from the brass adaptor by using PTFE tape. You could also remove the gland nut from its seat and wrap some around the tap spindle then, using the gland nut to push the tape down the spindle, re-tighten the gland nut to stop the leak from the tap without making the tap impossible to operate.
Very interesting! I've seen such valve before, was it on AvE or Clive's channel hmm.
Julian: Twice you talked about "accumulated pressure in the back chamber". I think that when the needle closes the channel the pressure on both sides of the diaphragm is the same. What closes the valve is the spring.
When the water is let through the small channel the pressure in front of the diaphragm is larger than behind and now the front pressure of the water opens it.
Gaston Groisman yes! Even though this is an old video I was going to make the same comment but checked to see if someone had already made the same comment. And you have :)
It really doesn’t matter how weak the spring is, it just has to apply *some* force (even tiny tiny) to mean the closing of the valve.
For me, it’s that which is the genius of this invention from 1910 or whatever.
Interesting video, Julian
One more detail, the surface area on the back of the valve is larger than the front, and thus even at the same psi there is more force holding it closed, venting the back pressure permits it to open of course.
This is the standard way that water pressure valves have worked for decades. They use the water pressure itself to operate the valve that controls the water pressure.
What are your thoughts about wiring a panel mount on/off switch to this? I'd like to be able to turn it on and off without having to screw off the front plate. They sell water proof panel mount switches. It's going to be used for a mister system so the auto settings will only be used for when we want to run the misters on a hot day. It would be nice if I could just turn the dials to a setting, screw on the front plate, and only have to hit the button when using.
You need ptfe tape to solve the leaks
I have to say, as I only started fiddling with electronics a few months ago, mechanics are vastly more evolved than electronics. In analogs it is almost without limits, whereas electronics is like building with blocks. Quite strange really, as electronics aren't exactly a new thing. I wonder if the quest for speed and going the digital route is holding us back. It seems easier (cheaper?) to convert to digital going through a microcontroller and then back to analog than it is to make a discrete analog device, even for the simplest task.
Also it's rather amusing to watch Mr. Ilett and Mr. Carlson go on about the mechanics in length, while the electronics is so obvious to them it's barely mentioned. Mr. Jones and especially Mr. BigClive doesn't seem to dwell so much on the position of screws.
My toilet cistern has that kind of valve in it. Took me a while to get my head round it first time it needed fixing.
Mine too. The supplied diaphragm was shit and was split within 6 months, leaving the cistern empty as it wouldn't hold back-pressure. Suffice to say when the guy from the housing came to repair it I blagged a few of them for spares.
Yeees, you know what we want!!!
First comment Amigo! Usted gana gran premio de hoy!
ya sabes lo que quiero. abrazo
No esperaba encontrarte acá. Tienes uno de estos? busco opiniones de este modelo
I had to figure how these worked out by myself when I took one of these apart when I was a kid. It took a while.
have you got a chance to check out roughly how long can the batteries last?
A lot of valves for in-ground yard/garden sprinkler systems work on the same principal,but use a solenoid instead of a motor/cam/plunger. Also of note,they're commonly rated 24Vac,but I've found that they will often function from a 9V battery,or similar.
This is a no power needed on version then. those solenoids would have an armature electromagnetically held back from a spring. i thought a solenoid generally referred to a springed electromagnetic operated armature (used in other things like door locks and relays)
A very entertaining presentation. One wonders if there is an electrical/electronic analog for how the solenoid valve works. Though the problem of mains electric (the equivalent of mains pressure water) with delicate electronics (the equivalent of those tiny vents) would be problematic.
I wondered the same thing
Hi Julian, I was thinking along the lines of an equilibrium valve as per we can find in a float operated cistern valve, but are there not similarities to the gas valves operated by, for example, a thermocouple? Very neat anyway.please include a subset of plumbing investigations, but I will sub anyway. I am captured. Muchas gracias desde el chico electricista en el distrito de lagos, inglaterra.
I share your enthusiasm for this water timer. It’s a pity it won’t work on gravity fed systems. Do you think increasing the spring strength and/or coating the diaphragm in vaseline would work?
Graham
.
Is there a way to modify this timer to change frequency from hours to minutes and water time to seconds instead of minutes?
Or just make a new circuit instead?
This is also the way a gas pressure valve works only its all mechanical. The gas tank on my roof reads the psi in the storage tank which is periodically filled when I pay for more. From that is a pressure regulator with this device. It has an adjustment screw which varies the amount of tension on the diaphragm thus providing a very small movement regulating a much higher tank pressure. No matter how low (or high )the pressure is in the tank, within reason, the gas pressure to my stove remain adjustable from the diaphragm. Of course, the whole thing is sealed shut and made repairable by the manufacturer to protect us from ourselves.
Protect us from ourselves...much like what the government is trying to do to us...
Would be interisti g to see this thingy working with arduno nano with remote rf
one small correction
in the closed position the spring is what holds the diaphragm closed because the water on both sides of the diaphragm has the same pressure
Well. There's also the difference in area on the diaphragm. The incoming water can only push on the center of the diaphragm. The water in the chamber pushes on the whole diaphragm.
The pressure is the same on both sides, but not the total force on the diaphragm is not.
valve works like the ones in washing machines kept closed by the water pressure
Hello Julian,
If I got it right you said there is no endpoint sensors on the motor, what happens if power is removed during the travel of the piston? will the water pressure push the rest?
Regards Stefan
So, I have a silimar modela to this one, just it's a digital one from Aqualin.
It worked just fine for 6 months, and then I noticed that my water tank was going low too fast, and I realized that the timer valve was leaking. It was not leaking to the outside, but it was leaving a little water pass by even when in closed position.
Any idea how can I fix it?
Hi Julian
I have a 6 of these and they all have the same kind of issue (they require mains water pressure to work) i have two water barrels connected together and am only getting a dribble at the output.there is a fair amount of pressure from the 400 liters . Ive tried to remove the spring, cut the spring in half, drill a larger hole in the solenoid end. (am now about to drill a larger hole in the diaphragm end as well. ) (and also going to replace the tap on the barrel with a larger diameter tap .) in your wisdom which of these or an other idea would allow full flow with little pressure.
Bạn hãy mua loại van bi nhé:
Zero Pressure Ball Valve Watering Timer Garden Irrigation
Is there any way to Increase the current?
Because the timer decrease it
Hi Julian, nice educative video. Do you know what is the lowest pressure this would work on. I want to use it from a rainwater barrel, maybe 1 meter from the ground. Thanks in advance.
Hi Calin,gravity flow pressure won’t close it unfortunately
Nó đây:
Zero Pressure Ball Valve Watering Timer Garden Irrigation
Whats with those blinking led things next ro your tap? And why does one have a cut positive wire??
the H-bridge is built out of 2x pnp and 2x npn (ss8050). The remaining 2 npn's will be to pull the pnp's to gnd (to activate them)
you should insert a second rubber washer inside the brass fitting which attaches to the faucet in order to stop the leaking
look up surestop water switch,same principal, but manually operated by you!
On a more serious note. Yeah it's clever how they use the motor driven plunger in place of an actual solenoid in this arrangement. Has a huge advantage when running off a couple of batteries in that it does not need be constantly energised to keep the valve open. I reckon those extra transistors are to do some kind of voltage level shifting and/or inversion to make the H bridge work.
Yeah, the other 2 NPNs will pull the PNP bases down to 0V.
Use some Teflon Tape on the tap threads, and yes, replace your tap washers
Very interesting. I bought a very similar item from Amazon for £12, but it doesnt work in the same way. Mine uses a ball valve in which a motor turns the ball 90 degrees each time you activate the switch or timer. It seems its a lot simpler method but not sure which is best.
The ball valve is better imo, the control electrinics are simpler, it's mechanically simpler, it doesn't require a minimum inlet pressure and it doesn't clog as easily. The other one is more clever though
I wonder how this would operate at low pressure? Like a gravity fed rain barrel system.
Bạn hãy dùng loại van này nhé:
Zero Pressure Ball Valve Watering Timer Garden Irrigation
Kind of like a mechanical transistor. A small flow of water controls a larger flow of water. My lawn sprinkler system vales work this way. I was very impressed with the design once I figured it out. I believe it uses mechanical hydraulic advantage to move the diaphragm. The chamber on the back of the diaphragm has a larger surface area so the tap water pressure pushes harder on the diaphragm (more pounds per square inch) to close it against the incoming tap water pressure. Very ingenious.
Is there a way that i can use this kind of timer to make a automatic dog feeder...where I can connect this to a tub full of dog pellets and use it while we are out on vacation? suggestions please......
Thanks,,,,,,,,,,,,,,,,