Have you ever wanted a little plant to brighten up your desk or home, but you're afraid that you'll forget to water it? Fear no longer! Using an Arduino, a scavenged wall-wart, and a peristaltic pump, you can set up your plant to be watered as often as you like, from a jug or any other vessel. To be as accessible to as many people as possible, this tutorial can be done without soldering. That being said, the advantage of soldering is increased robustness and reliability.

Step 1: What You'll Need

What you'll need:

(x1) Arduino UNO rev 3 (http://adafru.it/50)

(x1) USB cable (http://adafru.it/62)

(x1) 1N4001 diode (http://adafru.it/755)

(x1) PN2222A transistor (http://adafru.it/756)

(x1) 12v 1000mA DC power supply (http://adafru.it/798)

(x1) peristaltic pump (http://adafru.it/1150)

(x2) alligator clip test leads (http://adafru.it/1008)

(x1) 220 ohm resistor (anything between 125 - 333 ohms will work) (not pictured)

(x1) jug, glass, vase, or any other vessel that can contain water (not pictured)

(x1) a piece of scotch or electric tape (not pictured)

Tools: wire snippers, soldering iron + solder (not pictured)

<p>How do you stop the transistor from burning?</p>
<p>You said:-</p><p>The PN2222A transistor is great for this purpose because it can handle 5v from the Arduino without any resistors.</p><p>This is total and utter rubbish and will result in the Arduino being damaged. The Arduino has a pin limit of 40mA that is the limit of what it should supply, not the limit of what it can supply. It is likely that the base current without a resistor is being limited to about 80mA by the internal impedance of the Arduino pin and that is stopping the transistor from frying. This current is twice the level where damage to the Arduino is being done. You NEED a resistor, 1K should be fine. No doubt you will say it works, but your Arduino will fail a lot sooner that it otherwise would have.</p>
<p>I see that you live up to your name. But thanks for catching my mistake! I've updated the Instructable.</p>
<p>Hi!</p><p>Here, 1K prevented the pump to get enough current. I had to use a 220 resistor to make it work. </p>
<p>Ah, good catch. I think you are correct in general -- the datasheet gives an example of saturating the transistor with only 15mA, so with 5v you'd want a maximum of 333 ohms. To limit the current to only 40mA to protect the Arduino, use a minimum resistance of 125 ohms. So 220 is great because it's a common resistor and is between 125 - 333.</p>
<p>Since this Instructable has been getting a decent amount of traffic, I'm going to update it soon with a proper schematic, so no one else fries their boards. Thanks for enjoying it despite all the issues!</p>
<p>Dear author,</p><p>can i use a normal and cheaper aquarium pump instead of peristaltic pump since I am planning for a demo only. Urgent Please, as we have a science project next week. </p>
If your aquarium pump runs on 12v, then yes. If it's the type you plug into a wall socket, then no (you'd need to use a relay or PowerSwitch Tail, which would be as expensive as the peristaltic pump). Best of luck with your project!
<p>Is there any alternative for PN2222A ??only japan models are available here HELP!</p>
<p>Hi,</p><p>Can someone help with this 1K resistor issue ? I'm a total newbie in electronics. As a proof, I fried my Adruino in attempt to set this up :(</p><p>If there's anyone can tell me a dummy's guide in connecting the resistor. What wattage should I get for the 1K resistor ? and if it's not connected to the A0 pin, what should I change in the code to make it work ?</p><p>Thanks a lot! </p>
<p>Great tutorial, but my transistor gets extremely hot and smells like it is burning. Any idea what's happening? I am new to electronics so forgive me if it is a simple issue but I just cant figure it out.</p>
<p>Never mind I figured it out by myself. I did notice that connecting the resistor base to A0 did not do anything so I connected it to digital pin 2 and altered the code a tiny bit and everything works perfectly.</p>
<p>Very Easy instructions...Thank u for Letting us make this project</p>
<p>good job!</p>
<p>I made this - thanks a lot for the inspiration! But with me, the 1k resistor was too much, so it wasn't working. I changed to a 220, and then it worked. I hope this won't fry my arduino...</p>
<p>I made this with a few other instructables, so mine has a soil moisture sensor $3, connected to pin A5 and using an ethernet shield and set up a very simple website to monitor the moisture status of my plant. code below,</p><p>#include &lt;SPI.h&gt;</p><p>#include &lt;Ethernet.h&gt;</p><p>byte mac[] = { 0x00,0x1F,0xF3,0xD7,0x09,0x4C }; //physical mac address</p><p>byte ip[] = { 10, 0, 0, 253 }; // ip in lan (that's what you need to use in your browser. (&quot;;)</p><p>byte gateway[] = { 10, 0, 0, 1 }; // internet access via router</p><p>byte subnet[] = { 255, 255, 255, 0 }; //subnet mask</p><p>EthernetServer server(80); //server port </p><p>String readString;</p><p>int relay1 = 2; //relay1 on pin 2</p><p>int soil=0;</p><p>int motorPin = A0;</p><p>//00:1f:f3:d7:09:4c</p><p>void setup() {</p><p> // Open serial communications</p><p> Serial.begin(9600);</p><p> pinMode(relay1, OUTPUT);</p><p> // start the Ethernet connection and the server:</p><p> Ethernet.begin(mac, ip, gateway, subnet);</p><p> server.begin();</p><p> Serial.print(&quot;server is at &quot;);</p><p> Serial.println(Ethernet.localIP());</p><p> Serial.begin(9600);</p><p> pinMode(motorPin, OUTPUT);</p><p>}</p><p>void loop() {</p><p> /*========================================Soil sensor / pump mechanism============================================</p><p> using a 12v pump on 9v analog pin pump is triggered when moisture value falls within certain threshhold.and stops </p><p> immediately once it is satisfied.</p><p> */</p><p> // read the input on analog pin 5:</p><p> int sensorValue = analogRead(A5);</p><p> sensorValue = constrain(sensorValue, 485, 1023);</p><p> // print out the value you read:</p><p> if (sensorValue &gt; 900)</p><p> {</p><p> digitalWrite(motorPin,HIGH);</p><p> }</p><p> else digitalWrite(motorPin,LOW);</p><p> //map the value to a percentage</p><p> soil = map(sensorValue, 485, 1023, 100, 0);</p><p> // print out the soil water percentage you calculated:</p><p> //Serial.print(soil);</p><p> Serial.println(&quot;%&quot;);</p><p> delay(1000); // delay in between reads for stability</p><p> // Create a client connection</p><p> EthernetClient client = server.available();</p><p> if (client) {</p><p> while (client.connected()) { </p><p> if (client.available()) {</p><p> char c = client.read();</p><p> //read char by char HTTP request</p><p> if (readString.length() &lt; 100) {</p><p> //store characters to string</p><p> readString += c;</p><p> //Serial.print(c);</p><p> }</p><p> //if HTTP request has ended</p><p> if (c == '\n') { </p><p> Serial.println(readString); //print to serial monitor for debuging</p><p> client.println(&quot;HTTP/1.1 200 OK&quot;); //send new page</p><p> client.println(&quot;Content-Type: text/html&quot;);</p><p> client.println(); </p><p> client.println(&quot;&lt;HTML&gt;&quot;);</p><p> client.println(&quot;&lt;HEAD&gt;&quot;);</p><p> client.println(&quot;&lt;meta name='apple-mobile-web-app-capable' content='yes' /&gt;&quot;);</p><p> client.println(&quot;&lt;meta name='apple-mobile-web-app-status-bar-style' content='black-translucent' /&gt;&quot;);</p><p> client.println(&quot;&lt;link rel='stylesheet' type='text/css' href='http://randomnerdtutorials.com/ethernetcss.css' /&gt;&quot;);</p><p> client.println(&quot;&lt;TITLE&gt;SMART Home Control&lt;/TITLE&gt;&quot;);</p><p> client.println(&quot;&lt;/HEAD&gt;&quot;);</p><p> client.println(&quot;&lt;BODY&gt;&quot;);</p><p> client.println(&quot;&lt;H1&gt;VENUS CONTINGENCY home page&lt;/H1&gt;&quot;);</p><p> client.println(&quot;&lt;hr /&gt;&quot;);</p><p> client.println(&quot;&lt;br /&gt;&quot;); </p><p> client.println(&quot;&lt;H2&gt;home to the Arduino-Based Self-Regulating Venus Flytrap&lt;/H2&gt;&quot;);</p><p> client.println(&quot;&lt;br /&gt;&quot;); </p><p> client.println(&quot;&lt;a href=\&quot;/?potmoisture\&quot;\&quot;&gt;Refresh pot% &lt;/a&gt;&quot;);</p><p> if (readString.indexOf(&quot;?potmoisture&quot;) &gt;0){</p><p> client.println(&quot;&lt;H3&gt;current soil level is &quot;);</p><p> client.println(soil);</p><p> client.println(&quot;%&lt;/H3&gt;&quot;);</p><p> }</p><p> client.println(&quot;&lt;a href=\&quot;/?waterlvl\&quot;\&quot;&gt;Refresh waterlvl% &lt;/a&gt;&lt;br /&gt;&quot;);</p><p> client.println(&quot;&lt;br /&gt;&quot;); </p><p> client.println(&quot;Created by Joshua Kiefer and Jacob Kiefer&quot;);</p><p> client.println(&quot;&lt;/BODY&gt;&quot;);</p><p> client.println(&quot;&lt;/HTML&gt;&quot;);</p><p> delay(1);</p><p> //stopping client</p><p> client.stop();</p><p> //controls the Arduino if you press the buttons</p><p> if (readString.indexOf(&quot;?potmoisture&quot;) &gt;0){</p><p> digitalWrite(relay1, HIGH);</p><p> }</p><p> if (readString.indexOf(&quot;?lamp1off&quot;) &gt;0){</p><p> digitalWrite(relay1, LOW);</p><p> }</p><p> //clearing string for next read</p><p> readString=&quot;&quot;; </p><p> }</p><p> }</p><p> }</p><p>}</p><p>}</p>
I need a program which can start a 5v relay automatically daily in 4 pm of arduino uno
<p>I fried the board (cheep copy anyway), and now I know why as you can see in the specs down below of max current the different pins can handle, and as a couple of people have noted. This motor draws about 300mA. My projects has to fill about half a liter of water and the time of running the motor is therefor about 10 min. </p><p> http://playground.arduino.cc/Main/ArduinoPinCurrentLimitations</p><p>I gonna try to switch a transistor on and of instead so the motor will work on a separate circuit. Will share when I succeed. </p>
<p>Sorry you fried your board! You weren't trying to run the motor directly off the board itself, right? This design already uses a transistor. That being said, people more knowledgeable than myself are saying to use a 1k resistor in series between the board and the base pin of the transistor, so make sure you do that.</p>
No worries it cost me 10 bucks :), it was worth it. Yes I connected it as described so the 12v 300mA if Im understanding it correct had to travel thru the board, ground to collector and + to Vin. I red that post and put the 1k resistor on. But I have seen schematics that are using the arduino as a trigger of the base of a transistor which then control a bigger load and the ground is the only common place so to speak to somewhat isolate the circuit. <br><br>I had a timer on as well, in the wall and a transformer(12v) going to the board, so when I started to fiddle with the timer something sparked and it smelled burned. May have something to do with BackEMF from the timer Im guessing and the overload of the pin. <br><br>I need to control the pump so it pumps about a liter of water three times a day. I gonna try another approach.
<p>Ah, I see what you mean about the Vin pin. But with a genuine Uno, the Vin pin appears to be connected directly to the incoming power supply with nothing in between: <a href="https://www.arduino.cc/en/uploads/Main/arduino-uno-schematic.pdf" rel="nofollow">https://www.arduino.cc/en/uploads/Main/arduino-uno...</a></p><p>But yeah, 3 liters per day is a lot. Best of luck!</p>
<p>Hi</p><p>&quot;The PN2222A transistor is great for this purpose because it can handle 5v from the Arduino without any resistors.&quot;</p><p>Sorry that is wrong, the Veb is 6V, this is the reverse bias breakdown voltage of the 2N2222A not the forward drop which is 0.6 to 0.7Vdc</p><p>Please!!!! Place a 1K resistor between the output of the arduino and the transistor base, to limit base current.</p><p>You are very lucky if you do not have a base resistor to not have caused damage to your arduino and or 2N2222A.</p><p>Tom</p>
<p>Thanks for the info, I've updated the Instructable to reflect the 1k resistor.</p>
<p>hello, first of all i want to thank you for such a helpful information. Sir, i m from computer faculty so i want to innovate this idea with mobile app. Can you help me out for basic idea about what should i do for these.</p>
<p>I would use a Particle Core or Particle Photon. They're essentially wifi-connected Arduinos that you can program and control via the web. Once you understand their API, it should be no problem to integrate it into an app.</p>
<p>alrite, i made it. but what can i do to check water level in the container. am using a submersible pump that should not be used without it being completely submerged. so it helps to have some way to check if the water in the reservoir is getting depleted</p>
<p>You have a great project, I like it when its simple. I have a problem with your code though, I can't get wait time beyond about 30 seconds. I think its limited to 32767 ms, but with the ()'s it should go farther. What version of Arduino are you using.</p>
<p>instead of just delay(waitTime) you can use:</p><p><br>int waitTime = 32000;</p><p>int cycle = 0;</p><p>void loop(){</p><p>...</p><p>while(cycle&lt;1000){ //if you waited waitTime x Cycles you can go on</p><p>delay(waitTime); //wait 32 seconds<br>cycle+=1; //increase cycle by 1</p><p>}<br>cycle=0;</p><p>....</p><p>}</p>
<p>Hmmmm good point, you may have to use a long instead of an int.</p>
<p>I just love it when a GREAT project such as this is posted how all of the &quot;experts&quot; pop up to give advice on how to &quot;do it better&quot;...</p>
<p>I'm very glad you like it! I actually appreciate all the comments on how it could be improved, because it opens my eyes to things I hadn't thought of, and broadens my perspective.</p>
<p>Great project! Nice job.</p><p>I did not want to sacrifice my arduino for it, and made one with these parts :</p><p><a href="http://www.banggood.com/Soil-Hygrometer-Humidity-Detection-Module-Moisture-Sensor-For-Arduino-p-79227.html" rel="nofollow">http://www.banggood.com/Soil-Hygrometer-Humidity-D...</a></p><p><a href="http://www.banggood.com/1-Channel-5V-Relay-Module-Shield-Board-For-Arduino-ARM-PIC-AVR-DSP-ARM-p-914846.html" rel="nofollow">http://www.banggood.com/1-Channel-5V-Relay-Module-...</a></p><p>an aquaruim waterpump and a 5volt powersupply. </p><p>Let it grow !</p>
<p>Great idea, and very cheap! I didn't realize that sensor could operate without an arduino. Did you have any trouble calibrating it so the soil had the right moisture level?</p>
<p>There is a little blue potentiometer on the board, it was very easy to calibrate the relay. <br><br></p>
<p>You should consider writing an instructable for your project! </p>
<p>Very nice and good tutorial! Congrats on it! </p><p>However there is one thing of which I am concerned. I checked the data sheet of the pump and found out that the current of the pump motor is 200-300 mA. Arduino max current output is 30 mA. Will not the motor destroy Arduino? Please explain if I am wrong (I would like to learn! :))</p><p>Thank you and congrats again!</p>
<p>The current limits for the Uno are 40mA from any one I/O pin or 200mA from all I/O pins combined, and 50mA from the 3.3V supply pin. </p><p>The only I/O pin he is using is A0 to drive the transistor which will be very well under 40mA. </p><p>I'm not sure exactly what the current limit for the 5V supply pin is. I think it might be 1.5amps, but it's at least 500mA which is the most that can be drawn over a standard USB port. </p><p>However, he is not using the 5V supply pin to power the pump (which would be bad because dropping 12-5=7volts @ 300mA would require dissipating 2.1 watts of power which would definitely overheat the voltage regulator)- he is using the Vin pin which he is supplying with 12V. That is, the same 12V supply that is powering the Arduino through the 5V regulator is directly connected to one side of the transistor. The pump is connected to the other side and when A0 goes HIGH, the pump will draw current directly from the 12V supply. More explanations: </p><p><a href="http://bildr.org/2011/03/high-power-control-with-arduino-and-tip120/" rel="nofollow">http://bildr.org/2011/03/high-power-control-with-arduino-and-tip120/</a></p>
<p>You would be correct if we were powering the pump directly from the arduino. However, we are only using the arduinio to switch on a transistor. The transistor can handle much higher current and voltage than the arduino.</p>
<p>Dear osmithy. Thank you for your reply. I don't understand then. :) What is powering the pump? From the schematics I see that the pump is powered from the arduino 5V pin and the transistor is controlled by the A0 analog pin. I don't see any other power source. I am confused. Please help.</p>
<p>Nice project. I think though that the container you are using might be empty pretty soon :-)</p>
<p>Thanks! The container runs out in about a week which is not bad.</p>
<p>not too bad :-)</p>
<p>very nice osmithy. you can easily add a sleek plant arm to the pot, so it has light..! please check out my designs, i'm in the process of combining the two technologies...</p><p><a href="https://www.instructables.com/id/USB-powered-LED-plant-light-20/" rel="nofollow">https://www.instructables.com/id/USB-powered-LED-pl...</a></p><p>love &amp; peace...</p>
<p>Really cool! I posted a comment on your project.</p>
<p>I found a cheap plant waterer on indeigogo crowdfunding. https://www.indiegogo.com/projects/daisy-si-smart-plant-waterer</p>
<p>Wow, it looks like they don't even use a pump, just gravity. That allows their device to run off AAA batteries for years instead of needing to be plugged in. Pretty cool!</p>
<p>Great project! I have an arduino that is just collecting dust in my project box. I wonder how difficult it would be to measure the moisture content of that water and so make the unit almost autonomous. Here is a dirt cheap sensor:<br>http://goo.gl/5MXSyO Shipping is free but it can take between 4 to 6 weeks.</p>
<p>Actually that is not really difficult tmorsch. All you need to do is make the sensor part of a voltage divider and let the arduino measure the voltage over that divider:</p><p><a href="https://www.instructables.com/id/Watering-your-plants-with-a-microcontroller" rel="nofollow">https://www.instructables.com/id/Watering-your-plan...</a><br>In fact you dont even need an Arduino: </p><p><a href="https://www.instructables.com/id/Irrigating-your-garden-with-an-opamp-The-circuit/" rel="nofollow">https://www.instructables.com/id/Irrigating-your-ga...</a></p><p>In fact, the sensor that you mention has an Op amp as a comparator, on that little companion board and in fact you dont need an Arduino to make an automatic irrigator with that, only need to attach a relay to the board.<br>However, some of these cheap humidity sensor boards actually give a HIGH signal when the resistance on the moisture sensor is LOW (i.e. when the soil is wet), so a relay would do exactly the opposite of what you want: irrigate when it is wet. In that case you either would have to use the NC contact of the relay (but yr relay would be pulling power when there is no irrigation) or you would need to switch the relay via an inverter (e.g. a PNP transistor).<br>If you dont want to wait 4-6 weeks for ordering, just use two galvanized nails with yr Arduino and grab the program I put in my instructable)<br></p>
<p>Wowwwww that is so cheap! You could absolutely make it autonomous if you used one of those, and it wouldn't be difficult at all. I knew about the one Adafruit sells but it's $50, so I didn't use it.</p>
good idea..but what you are doing is a on and off timer ...this you can do with a 555 ..cost too less...so i expect a microcontroller to do some more complex task...any way thanks for sharing

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