gear 0.2 - Page 1
Forum section: electronics / beginners

author: uc
author_rank: Contributor
timestamp: May 25, 2018, 03:51:02 pm
content: This is my project.Lets START:My wife received a green house for here 60 years present from our children.Now I finally erected it.She is complaining that she is not able to visit our grandchildren due to all the “growing stuff” that needs water.So my project is:Step 1 (today)1. Power input: 220W AC2. Safety against electric shock.3. Individual valve regulated water injection for 10 units (several plants in one unit). Based on liter/dayStep 2 (future)1. Power input: 220W AC2. Safety against electric shock.3. Individual valve regulated water injection for 10 units (several plants in one unit). Based on moisture in the dirt.Step 3 (future future)1. Power input: 220W AC2. Safety against electric shock.3. Individual valve regulated water injection for 10 units (several plants in one unit). Based on liter/day optimized for moisture in the dirt and monitoring and regulated via apps.Step 4 (Future Future Future)1. Power input: 220W AC2. Safety against electric shock3. Make nice happy plant LEDs so your wife knows which pots are hydrated... preferrably changing colors every few seconds on a 3d printed sunflower maybe? This will be icing on the cakeI was thinking to do a "Flowchart" for the Step 1 before I order any components.Parallel, I will also follow "Mr Shock" advise to test the wiring with a signal Sim. Refer to "gear 0.1Could you guys give me some examples of "Flowchart".Or is it a beter way ?Do you gues have a idea how to sart a project without lose time?Take care//uc

author: Benta
author_rank: Super Contributor
timestamp: May 25, 2018, 03:59:02 pm
content: 220W? Do you mean 230 V?

author: uc
author_rank: Contributor
timestamp: May 25, 2018, 04:08:53 pm
content: Yes sorry,wrong copy/paste. You are right.

author: rstofer
author_rank: Super Contributor
timestamp: May 25, 2018, 11:07:16 pm
content: The very first decision point is which solenoid valves. How many volts, how much current, AC or DC?From this you will come up with the design for a solenoid valve driver. If the current is high or the solenoid is AC, you may want to use a small relay. Here you need to pick the coil voltage so your electronics can deal with it. 12VDC seems reasonable and if the current is low enough, you can control it with a transistor. You also need a reverse biased diode across the relay coil - Google for 'transistor relay driver'. You could also use a Triac to control the AC valve - more study required...http://www.edgefxkits.com/blog/relay-driver-circuit-using-uln2003-ic/My goal would be to get voltages for the solenoid and relay that are reasonable and nowhere near mains voltage levels. Maybe 24 VAC for the solenoids and 12 VDC for the relay coils.Now all you have to do with the timer is trigger the transistor. If the timer is capable, it could possibly drive the solenoid directly or maybe drive the relay. Go to your local home center and look through the sprinkler timers. So what they do. Better yet, buy one with enough channels (I have 2 with 13 channels each) and see if they can be used somehow. Or just repurpose the parts.By all means necessary, stay away from mains voltages. Make your gadget plug into a wall outlet, preferably with an external wall wart providing all the power. If the wall wart is 12VDC, you can always drop it down to 5V for logic.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: May 25, 2018, 11:41:18 pm
content: Setups to do this are widely available commercially in the US. I assume this is also true in your country.So the very first step is figuring out why you don't just purchase one. You won't save money, but it is possible that you will incorporate features you can't buy or will enjoy the trip enough to make it worth while. Determining which features you can't get in the commercial systems that you need or want will get you a long ways in defining your design.You should also consider another path - start with a commercial system and then upgrade in steps as you propose with your own design.Things to pick up from the commercial systems:1. They all use 24 AC volt solenoid valves with a step down isolation transformer to run them from the mains. Logic/display circuitry power is also derived from this isolated 24 volt supply2. Most have battery backup so that watering program is not lost during any brief power interruption.3. Most incorporate a backflow prevention device to prevent contamination of the source water supply under a number of fault conditions.4. None that I have encountered has really solved the user interface problem. Some are better than others, but there is real room for invention here. Part of the problem is the limits on I/O caused by the low selling price.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: May 26, 2018, 02:36:28 am
content: Quote from: uc on May 25, 2018, 03:51:02 pmOkay, Step1 would be to study what, when, where, and how you want to accomplish Step 1. Guess what the flowchart for Step 2 would be...In engineering, I don't do a flowchart, (however others might,) even when I write software. I simply ask myself the 3Ws and an H. But then I tend to just jump in and start working different angles right away and get a sort of outline of the tasks in my head. I logically determine the tasks in what I consider first things first. You may find some other way that is better for you, and that is the point. For me, it is a mental exercise.You have to realize that folks on this forum have varying ways of doing things and also have varying levels of experience. You will develop what works best for you as you work your problems. What I always tell my young engineer co-workers, while working a problem you put one foot in front of the other as you take one step at a time. Jumping ahead or taking shortcuts causes delays.Just my 2 cents...

author: uc
author_rank: Contributor
timestamp: May 26, 2018, 10:45:00 am
content: My first approach to solve the problem on step 1.At this stage I would like to avoid any micro controller but maybe it is impossible. Refer to my other post and comment from Larsdenmark (*) gear 0.1.Here is my idea:Time generator -> Counter 24h->Trigger->Start pump and open valves->delay 5s for water plants->close valve and stop pump->Loop back to Counter 24h.In order to take q(water) out of the equation I will use a valve and just adjust the flow by trial.(*) Quote: “Step 1 is difficult. You need to be able to measure how many liters you supply and you need to be able to count days/hours/minutes.”So is it possible to make "Time generator -> Counter 24h->Trigger->"?

author: tpowell1830
author_rank: Frequent Contributor
timestamp: May 26, 2018, 02:45:14 pm
content: Quote from: uc on May 26, 2018, 10:45:00 amI like your approach. There is no evidence that you need to test for presence of water at this point in your experiment. Keep it simple until the problem dictates otherwise.Just my 2 cents...

author: uc
author_rank: Contributor
timestamp: May 26, 2018, 02:48:36 pm
content: I it possible to use a MC14541B?If yes:The oscillator run at 0,1 Hz gives approx 655000s refer to “Encyclopedia of Electronic Circuits” page 582.655000s/3600c/h=182h but it is to long!Is it possible to run two (2) circuits in parallel asynchrony, enable split the time in half?Give 182h/2=92h=3.8dhttp://www.onsemi.com/pub/Collateral/MC14541B-D.PDF

author: tpowell1830
author_rank: Frequent Contributor
timestamp: May 26, 2018, 03:10:09 pm
content: Hmm, why that device? There are others if you want to spin your own rather than simply buying a timer made for such things such as this:https://www.amazon.com/DROK-Digital-Programmable-Switch-Controller/dp/B072QTWNGX/ref=sr_1_52?ie=UTF8&qid=1527346990&sr=8-52&keywords=24-hour+timerBut otherwise here is website that has a schematic (one of many):http://www.zen22142.zen.co.uk/ronj/24h.htmlI realize that you may want to do it yourself, without looking up ready made solutions, but mostly you need to use your own logic to yourself and ask the tough question: Will this do the job or do I need to rethink?Again, my 2 cents...

author: rstofer
author_rank: Super Contributor
timestamp: May 26, 2018, 03:24:09 pm
content: And what will be the user interface (UI)? How will you set the times for each zone? Will the time requirement change with the seasons? Do you need to be able to enable/disable select zones from time to time? How about a manual start of the entire sequence or, even harder, just one zone?There is a reason that modern sprinkler timers have displays and, in my case, a 30 position (?) rotary switch and 3 buttons.Although I suggested starting with the valves (and I still do), you need to get a handle on the big picture. It's easy to say "I don't want to use a uC" but it's a lot more difficult to come up with a usable device without one.What would be very cool is to make the controller run over WiFi and come up with a cell phone App for the UI. I have been kicking that idea around for years. Wandering all over the yard to adjust the controllers is a pain. A browser like interface would be perfect!Google for 'diy wifi sprinkler controller' - there are a lot of project videos.In 'gear 0.1' you said you didn't want to start with C/C++. You might want to revisit that decision. EVERYTHING is being done with microcontrollers, especially if it needs a UI.

author: uc
author_rank: Contributor
timestamp: May 26, 2018, 03:50:44 pm
content: Thanks, tpowell1830,My main purpose is to learn electronics fundamentals and build things and understand the basic behind it. I will build circuits and check theory against real life.My intention is not to take short cut and buy readymade solutions.But of course I need to keep my wife happy, so……I usually check forum and literatures for proposals and investigate datasheets for their applications.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: May 26, 2018, 04:17:09 pm
content: Quote from: uc on May 26, 2018, 03:50:44 pmThat is the impression that I have gotten from you. Using very basic systems is the best way to start, IMO. Think through the results of each decision and build on it. Also, I don't think that you are doing this just for your wife, I think you are doing this to learn. Building your knowledge base from the basics up is a great plan. Where many make the mistake of wanting to jump from zero to 100 instantly. Works for some, but not all.If I thought that you were trying to make a commercial product, which I don't, I would advise you in a different direction.

author: uc
author_rank: Contributor
timestamp: May 26, 2018, 05:17:35 pm
content: I am probably 40 years too late to make a commercial product including knowledge. On other hand, in my next life I would like to aim for electronic engineering instead of mechanical, refractory engineering and project managing.

author: uc
author_rank: Contributor
timestamp: May 26, 2018, 05:32:13 pm
content: Dear rstofer, the reason I try not to use microcontroller is that I want to try other ways before going that road. It might be impossible but I will try. Take care.

author: uc
author_rank: Contributor
timestamp: May 26, 2018, 05:59:19 pm
content: Dear CatalinaWOW,I am not planning to buy readymade one.I am not planning to do “reverse engineering” of existing one.This is just a interesting project for me, creating things in a safe manner.Q1 you say “They all use 24 AC” Could you please explain this? I do not understand.

author: rstofer
author_rank: Super Contributor
timestamp: May 26, 2018, 07:47:51 pm
content: It simply means that common sprinkler valves use 24 VAC for the coil. They may, or may not, work on DC. Let's assume they don't...Since it is 24 VAC, you can't control them with a single transistor or MOSFET but you can control them with a TRIAC. Even better is an optically isolated TRIAC because it separates the logic voltages from the coil voltages.Here is a project that comes from right here at EEVblog:https://www.eevblog.com/forum/beginners/circuit-to-control-sprinkler-system-with-arduino/Regardless of the uC versus <whatever> control scheme, you need some way to actuate the valves. The TRIAC circuit in this document is pretty nice.I would want to test some valves to make certain they didn't require more than 1.0 Amps. Simple test, rig up a 24VAC transformer and run the current through a DMM in series with the valve. It's important!If the current is more than 1.0A then you have to a) come up with a TRIAC than can handle more current or b) use a relay. The relay might as well be 24VAC (common supply voltage) and it can be controlled by a TRIAC. There's no way a small relay requires anything like 1.0A. I would probably use the relay in either situation because a short circuit in the solenoid valve might wipe out the relay but it probably wouldn't damage the rest of the system. BTW, fuse the 24VAC to protect the relay and wiring.https://www.digikey.com/products/en?keywords=VO2223This is where the numbers start hitting the project. There's a lot to think about when picking parts.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: May 26, 2018, 07:52:59 pm
content: All of the commercial ones that I am aware of operate the solenoids on 24 V AC. There are a few reasons for this. One, these systems operate in a wet environment in the presence of untrained people like your wife. Use of a relatively low voltage makes this safer. Two, this low AC voltage is easily derived from the mains using a transformer. This transformer also isolates the low voltage supply - another safety feature. Three, 24 volts as opposed to some other low voltage because this voltage had already been standardized for use in doorbell and HVAC applications, reducing the cost of components.Good luck with your project. I would suggest using the standard irrigation valves. Not much electronics to learn there, and lots of hydraulic and mechanical problems worked out and approved for connection to public water systems.

author: bingo600
author_rank: Super Contributor
timestamp: May 27, 2018, 09:28:04 am
content: I find a lot of 12v solenoids if i do this search on ebay.com: water valve solenoid@uc make sure to make a "low point" water tap.For emptying the valves & tubes , when (before) it gets freezing ...I had to replace the water solenoid on my washing machine, back in 2008 when it was -28C outside and unfortunately freezing i "Torpen"Was lucky it didnt break the pipes/BingoEdit: For this price (and free shipping to Sweden for orders over 39€) , i'd consider buying.https://www.amazon.de/GARDENA-Bew%C3%A4sserungscomputer-EasyControl-Bew%C3%A4sserungssteuerung-Batteriebetrieb/dp/B00GHEH8OE/ref=sr_1_1?ie=UTF8&qid=1527413709&sr=8-1&keywords=wasser+automatikMisc fittings you'd need anywayhttps://www.amazon.de/dp/B074CFLFW9/ref=sspa_dk_detail_5?psc=1&pd_rd_i=B074CFLFW9&pf_rd_m=A3JWKAKR8XB7XF&pf_rd_p=2444543729105426210&pf_rd_r=0HGWY7SAAM28C68W97EF&pd_rd_wg=AwsyO&pf_rd_s=desktop-dp-sims&pf_rd_t=40701&pd_rd_w=i8Pt0&pf_rd_i=desktop-dp-sims&pd_rd_r=cb4a5b4e-6191-11e8-b22f-9be43c3b90dc

author: larsdenmark
author_rank: Regular Contributor
timestamp: May 28, 2018, 10:55:42 am
content: If you aim for the timer based solution then you can get a timer IC:http://www.ti.com/product/LM555There are many companies that produce such ICs and they all end with the number 555. This IC can be used for a lot of things are quite cheap so you may wish to grab 10-20 of these for various experiments. This IC is an analog IC so there is no programming involved. You use resistors and capacitors to control the timing so you should get a collection of these as well.Unfortunately the 555 is not able to tell the time precisely, but I don't think the plants will mind that the timing shifts a little. Also the 555 is not stable for long intervals so I suggest that you create a system that starts the water flow every hour and let the water run for a short time.You can use another 555 to control how long time the water should flow for. You most likely want a potentiometer to be able to vary the duration.You need a solenoid valve to control the flow. I would recommend something that runs on 12 V. This will mean that you can run the entire circuit on the same voltage as the 555 has a maximum of 18 V (at least the one I link to). You want a valve that is turned off when the power is off (so you don't flood anything if the power goes away). You need a diode across the solenoid in order to protect the circuit.You can't control the solenoid directly from the 555 unless you can find a solenoid that uses very low current. Hence, you need something to drive the solenoid from the output of the 555. I would recommend a relay since these are simple to set up (you also need a diode across the relay in order to protect the rest of the circuit). For slightly more advanced solutions you can use a transistor (BJT) or a MOSFET (which is also a kind of transistor).This should amount to a nice DIY project and fiddling with the 555s means that you'll be able to use the scope to monitor all its signals!

author: uc
author_rank: Contributor
timestamp: May 28, 2018, 03:20:57 pm
content: The proposal fit me perfectI will do this!My aim is also to execute calculations on the circuit and take measurement and se if the numbers end up the same.Probably not but I will try