Welcome to the DIY Thirsty Plant Kit - Manual This is a step-by-step guide to making your own Thirsty Plant Detector. The equipment you should have at your station are wire strippers, wire cutters, wooden stirrer, water and Sharpies. We hope you enjoy this creative task, learn some new technological skills and apply them to your life in useful ways.
Technology Will Save Us Getting Started Top Tips Keep an eye out for the top tips. They are highlighted in a orange box like this! Making Time The kit takes about one fun filled hour to complete - depending on how creative you get with the personalisation of your marker. Useful Appendix Further information on all the components in this kit can be found in the appendix at the back of the manual. Learn about their use within the circuit you are building. Further Resources Information on how the circuit works alongside different ways to extend your Thirsty Plant Kit, such as adding and automated watering can or setting up a mini weather station can be found on our resource page: twsu.co 3
Making your DIY Thirsty Plant Parts: 1) 1x Plastic marker 2) 3x Waterproof casing pieces 3) 1x Solar panel 4) 1x Rubber tubing 5) 1 x Wire pair for sensors 6) 1x Double sided tape 7) 2x LEDs (Light Emitting Diodes) (1 x spare) 8) 2x 1M Ohm (Ω) Resistor (1 x spare) 9) 2 x Copper nails 10) 2x Mosfet (1 x spare) 11) 1 x Plaster of paris container Check your components to make sure you have all the parts to build your DIY Thirsty Plant! 4 Components
Technology Will Save Us 1 2 3 4 5 6 7 8 9 10 11 Top Tip Some components may look slightly different to the ones above, don t be alarmed, this is normal! Components 5
1 Making your sensor Find your empty plastic container and plaster of paris. Fill your empty plastic container 1/5 of the way with water, and using your fingers gently sprinkle the plaster of paris in. We do it this way to avoid getting air bubbles in the mixture and to make sure you get a smooth consistency. The plaster of paris will sink to the bottom. Keep adding until there is no more space left in the water and the powder just slightly sits on top. Then mix into a smooth consistency similar to that of double cream. 6
Technology Will Save Us Now find your rubber tubing and pair of nails. Using the wooden stands (or find something to hold the tubing if at home), place the tubing into the moulds and gently pour in your plaster of paris mixture, until the tube is full, making sure there are no trapped air bubbles. Step 1 7
Technology Will Save Us Now place your nails into the plaster of paris, making sure they do not touch one another - as this would create a short circuit. Top Tip If you try to place your nails and they sink all the way in to the head, your plaster is two watery. Simply wait a little for it to harden then try again until they hold themselves above the surface of the plaster. You have just completed your first homemade sensor. Now put this to one side to allow for it to dry. We will be coming back to it later on. 8 Step 1
2 LED Look at your marker. You will see an etched illustration of an LED with a short and a long leg. Now pick up your LED and match the long and short legs of the LED with the illustration. The long leg is the positive one - it wants power! Now bend the legs out at 45º to hold the LED in place. Top Tip Symmetry in components is very important. If something is asymmetrical it is trying to tell you something! In this case LED s have polarity which means they will only work one way and not the other. So be sure that they are inserted in the correct way! Step 2 9
3 The Resistor Find the 47k Ohm (Ω) Resistor (Look at the stripes: Yellow, Purple, Orange, Gold), Top Tip Resistors can be plugged in any way around. Their legs are the same length - which is a way to tell that it can be plugged in both ways. Also, if you look at the body of the resistor, you ll see that there are different coloured stripes. The stripes tell us what value the resistor is. Brown, Black, Green, Gold = 1M Ohm. The resistor s legs need to be bent at 90º before inserting into the marker. Bend the legs so the resistor looks like a staple. 10 Step 3
Technology Will Save Us Then place the resistor so that it sits flat against the marker in the right place, as etched on the marker. Resistors don t have polarity so they can go in either way and work fine! Flip the marker over and twist together the longer LED leg and the top leg of the resistor. Step 3 11
4 Solar Panel The solar panel is what will power your circuit - thanks to sunshine or other light. The solar panel has 2 wires attached to it: a red one ( positive or power) and a black one ( negative or ground). Top Tip If you touch the red and black wires to your tongue while holding the solar panel so it faces the light - you ll taste the tingly power! Take the top section of your waterproof casing. (The one with four square holes in each corner and a circular one in the centre) Then thread your two solar panel wires through the central circular hole and slide the panel up against the solar panel. You wont need to do anything to this panel until later on in this guide. 12 Step 4
Technology Will Save Us Insert the positive (red) wire into the marker where its labelled with a sun and + icon. Then flip over the marker and twist it together with the already twisted LED and resistor leg from the previous step. Top Tip Peel the film off of your solar panel! If you don t it will stop some sunlight reaching the panel and effect its performance! Step 4 13
5 Sensor Wires Insert both of the sensor wires (grey wires) into the marker where its labelled sensor. These wires can go any way around. Flip over the marker and twist together the right sensor wire and the bottom resistor leg. 14 Step 5
Technology Will Save Us Now insert the negative (black) solar panel wire into the marker where its labelled with a sun and - icon. Turn over the marker and twist together the black solar panel wire and the second sensor wire. Step 5 15
6 Mosfet The Mosfet acts as a gate between the LED and the moisture sensor. When the sensor is in your plant s soil, the resistance between the two nails in the sensor increases depending on how dry the soil is. If its completely dry, the resistance becomes infinite! (In other words, its as if there is air in between the two nails). When this happens the Mosfet allows the current to flow and the LED in the circuit activates! (It blinks :-) Insert the Mosfet in the same position as shown in the image - making sure that its metal back faces up towards the LED. 16 Step 6
Technology Will Save Us Turn over the marker and bend the Mosfet s legs at 45 degrees to hold it in place. Top Tip It helps to bend the middle leg up at 45 degrees and the outside two downwards at 45 degrees. As this means they are closer to the wires that each needs to be twisted to. Then twist the left Mosfet leg with the already twisted negative (black) solar wire and left sensor wire. Step 6 17
Technology Will Save Us Twist the middle Mosfet leg with the remaining negative (-) LED leg. Finally, twist the right Mosfet leg with the already twisted bottom resistor leg and right sensor wire. 18 Step 6
Technology Will Save Us Your completed twisted circuit should look something like this! The LED will flash at this point if you hold the solar panel to light. Dont worry, its meant to! This means that your circuit is working. Step 6 19
7 Attaching the sensor Now check your sensor and test to see if it is dry enough. (It will need 24 hours or so to be completely dry). Put it in a nice warm place to speed up its drying process! If it is dry, remove the sensor carefully from the rubber tubing. 20 Step 7
Technology Will Save Us Now snap the sensor - it will naturally snap at the correct point. (Like asparagus) Now find the ends of the sensor wires and wrap them tightly around the nails, taking extra care that they do not touch. If you want to secure the wires you can use a dab of hot glue to seal around the nails. Top Tip If your sensor is still damp then the LED will turn off at this point! Step 7 21
8 Fitting the waterproof casing Take the two remaining side pieces of your waterproof casing shown on the right. Next using the two slots in the side pieces of the waterproof casing, hook them on to your marker with the pointed side facing downwards. These should easily fit on to your marker. 22 Step 8
Technology Will Save Us Clip the top section of the waterproof casing on to the side panels using the four small clips on each corner. Top Tip It helps to hook one notch on each side first and then squeeze the other side in. Finally use your double sided tape to stick your solar panel on to the top of your waterproof casing to keep it securely in place. Step 9 23
9 Time to plant You have finished your Thirsty Plant detector! It should look similar to the photo. Now its time to place it in your plant. Insert the sensor into the soil making sure it is completely covered. 24 Step 9
Technology Will Save Us Now place the marker into the soil (its best to place the marker slightly in the shade so the LED is brighter) and the solar panel in direct sunlight. If your plants are adequately watered nothing will happen at this point, but if they are neglected and dry the LED will start flashing to tell you to water your plant and make it happy! Step 9 25
Congratulations! You have finished making your Thirsty Plant Kit. Now make it your own! Customize the casing of your kit using whatever you want. Stickers, Sharpies, Paint or if your feeling more adventurous you could completely reinvent the shape of the housing. When you are happy with your creation all that is left to do is choose your potted plant and away you go! For those of you who want to test your skills and learn more or just have that one special plant that you want to keep alive check out: twsu.co/thirstyplant You will find many more creations and hacks to expand your technological gardens. 26
Component Appendix Resistors - Resistors are used in a circuit to restrict the flow of electrical current and stop things from blowing up! The resistors are measured in Ohms. Solar Panel - Solar panels transfer energy from the sun s rays into use-able electrical current. Who needs batteries?! LED - A light-emitting diode is your basic electronic light. It is actually a Diode that happens to emit light! A diode allows current to flow in only one direction. This is why an LED is polarized - it only works if you plug it in the right way around! Mosfet - The Mosfet acts as a gate between the LED and moisture sensor. It allows the current to flows when the resistance in the sensor becomes infinite (i.e. no moisture). Components 27
Technology Will Save Us Copper Nails - Copper nails are used as electrodes in the plaster of paris sensor that we built. It is the resistance between the two copper nails that helps the circuit tell us when our plant is thirsty! Sensor Cable - Sensor cables are simply copper cable - the same kind used for speakers! Remember to twist the ends so they re easier to work with. Sensor Mould - The sensor mould is a rubber hose used to help cast the plaster of paris into the right shape. It has a slit down the side so we can easily remove the finished sensor when its hardened. 28 Components
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