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Humidifiers add moisture to the air. They can help people with dry skin, allergies, and respiratory problems. They may also help in preventing influenza and reduce snoring. I bought this AU$2 USB Mini Humidifier DIY Kit from AliExpress and went ahead and created a cute little 3D container for it. In this tutorial, I will show you guys how I designed and assembled the humidifier circuit into the 3D model. 3D Model While browsing the Internet, I found this cute little candle holder created by SERV3D on Cults3D.com. The design was very cute and I went ahead and upsized and customized the design to fit all my electronics bits into it. With the help of Microsoft 3D Builder, I modified the 3D Model. The model has 2 compartments. The top compartment is completely hollow to hold water in it. I kept the top section open to fill water into it. All the electronics bits will go inside the second compartment. Those two screw holes are to hold the rechargeable 18650 battery holder. This pipe like structure is for the wires to go from the top section to the bottom section. The top compartment is 9.5cm x 4.5cm. So, if we calculate the volume of the cylinder it comes out to 604cm-cube. By dividing the volume by 1000 we can get the volume of water that can be stored inside that compartment. So, it comes out roughly around 0.6 liters. At the back of the model, I created a grove to fit in a block of plastic that will house the TP4056 18650 battery charging module and a SPDT switch. The charging module gets super hot while charging, so I have given enough space in the block to keep the module cool. The bottom lid will cover and hide all the electronics bits into it. The top lid has a hole in the middle to house the humidifier straw. Thats it as simple as that. 3D Printing Once the 3D model was sorted, it was time for me to fire up my 3D printing oven and start printing these 3D models. As we all know, 3D printing is the process that uses computer-aided design or CAD, to create objects layer by layer. 3D printing is not a new technology, its been there since the 1980's, when Charles W. Hull invented the process and created the first 3D-printed part. Since then, the field of 3D printing has grown exponentially and holds countless possibilities. The 3D printing process fascinates me a lot and I sometimes love to sit near my printer and watch these layers getting printed. 3D Printing is a highly addictive hobby! There are so many things you can do using a 3D printer. From designing 3D Models to printing them using the 3D printer has now become my new hobby. I've been a "maker" since I was 10 years old, and have always constructed and made my own stuff. 3D printing for me is a blessing. I am totally lost in the 3D printing heaven. 3D printing has changed my electronics workshop life forever. Before when I used to order parts, I always used to wonder if the parts would fit into my project's resources... but after I got my 3D printer... it doesn't matter at all, because if it doesn't fit - I could design and print it myself. The 3D printer was definitely "The Missing Piece" from my electronics workshop. The entire printing process took roughly around 20hrs. After extracting all the 3D printed bits, I sanded them to give them a nice and smooth texture. This is the bottom cover, that's the top lid with a hole for the humidifier straw and a handle to open and close the lid. This block will hold the battery charger and the SPDT switch into it. The main body has the top compartment for holding water in it and the bottom compartment for housing all the electronics bits into it. Schematic The circuit is very simple. By connecting an USB Type-C charging cable to the TP4056 Module we charge the 18650 battery connected to the B+ and B- terminals of the module. The humidifier module connects to the OUT+ and OUT- terminals of the charging module via a SPDT switch. Using this switch we can turn on or off the humidifier. So, these are the components that were in the DIY Kit. A circular atomizer, two plastic holders, a straw and the main humidifier circuit board. I customized the board by adding a couple of male pin headers to power this unit using a battery and dropped a blob of solder to bypass the push button switch. To assemble, insert the atomizer into the black plastic holders along with the humidifier straw. Then connect the atomizer to the humidifier circuit board. In my project the circular atomizer will be way far from the circuit board. So, I will replace the short red and black cable with a long ribbon cable. Assembling The Bottom Let's start by soldering the battery holder to the B+ and B- terminals of the charging module. Then, let's solder the -ve connector that will power the humidifier to the OUT- terminal of the board. After that, let's solder a loose cable to the OUT+ terminal. Now, let's slide the humidifiers +ve connector and the other end of the loose cable into the plastic block. Then, solder these two cables to the SPDT switch and superglue it to the block. Then push the charging module into the groves of the plastic block. Once the block is all set, push it into the back of the main unit. After that, using a couple of screws attach the battery holder to the bottom of the unit. I used hot glue to stick the humidifier circuit to the bottom of the unit. Once everything is in place, plug in the 18650 battery to the battery holder and push the white and black atomizers cable through the pipe like structure. After that, connect the atomizer's power chord to the humidifier and seal the bottom lid. Assembling The Top Be very careful while assembling the top. The atomizer has two sides. The one with more exposed metal area, touches the humidifiers straw. I soldered the atomizer to the white and black cable after passing it through the top lids hole. Then it was just a matter of putting the atomizer inside the two black holders along with the straw and then snap-closing it and pushing the setup through the hole. That's it, all done. Coloring I wasn't very confident about PLA being waterproof and not absorbing water leading to swelling and degrading of the biodegradable plastic. So, I went ahead and painted the inner bit with "Bitumen Waterproofing Membrane". Then, using Acrylic Colors, I painted the body of the 3D printed model. I gave the model a bit rustic look, but hey.. it totally depends on you how you want your project to look like. Final Demo To fill the container with water, you just need to lift the top lid and pour water into it. Once fully charged, the unit can run seamlessly for roughly around 10 hours. So, this is how my final setup looks like. Do comment and let me know if there are any scopes of improvement. Advantages Dry air causes moisture to evaporate from the skin and respiratory symptoms to worsen over time. Adding moisture to the air with a humidifier can counteract these problems. Humidifiers can help people who experience: cracked lips dry skin irritated eyes dryness in the throat or airways frequent coughs bloody noses allergies sinus headaches Disadvantages Dirty humidifiers : If the unit’s water tank is dirty, the vapor a person breathes will also be dirty. Too much humidity : excessive level of humidity can make breathing difficult and some allergy symptoms worse. Using hard water or tap water : Minerals from hard tap water can build up in the machine, causing it to wear down faster than expected. The humidifier can also push these minerals into the air, and a person may inhale them. Thanks Thanks again for checking my post. I hope it helps you. If you want to support me subscribe to my YouTube Channel: https://www.youtube.com/user/tarantula3 Video: View Full Blog Post: View References GitHub: View Stl Files: Download Wallpapers: Download Support My Work BTC: 1Hrr83W2zu2hmDcmYqZMhgPQ71oLj5b7v5 LTC: LPh69qxUqaHKYuFPJVJsNQjpBHWK7hZ9TZ DOGE: DEU2Wz3TK95119HMNZv2kpU7PkWbGNs9K3 ETH: 0xD64fb51C74E0206cB6702aB922C765c68B97dCD4 BAT: 0x9D9E77cA360b53cD89cc01dC37A5314C0113FFc3 LBC: bZ8ANEJFsd2MNFfpoxBhtFNPboh7PmD7M2 COS: bnb136ns6lfw4zs5hg4n85vdthaad7hq5m4gtkgf23 Memo: 572187879 BNB: 0xD64fb51C74E0206cB6702aB922C765c68B97dCD4 POL: 0xD64fb51C74E0206cB6702aB922C765c68B97dCD4 Thanks, ca again in my next tutorial.

Proximity sensing is a very common application in electronics. There are several ways to accomplish this. The most common way is by using a PIR sensor. PIR Sensor senses the change in ambient infrared radiation caused by warm bodies. I have already covered this in my Tutorial No. 5: "PIR Sensor Tutorial - With or Without Arduino". However, since PIR sensors detect movement from living objects, they can generate false alarms. These sensors are also inefficient in hot environments, as they rely on heat signatures. The other common methods of proximity sensing involve, using reflected ultrasonic or light beams. Using these sensors, the intruding object is detected by the reflected beam back to its source. The time delay between transmission and reception is measured to calculate the distance to the object. In this tutorial, we are going to look at another method of proximity sensing using "Microwaves" and "Doppler Effect". In my hand is an inexpensive RCWL-0516 Microwave Radar Motion Sensor. The RCWL-0516 microwave sensor detects "any movement" from "any object" and does not rely on heat, making it more reliable in hot environments. I am going to use this sensor to create a Geo-fence around my house to detect motion and get notifications. What is the Doppler effect? The RCWL-0516 module uses a “Doppler Radar” that makes use of the "Doppler Effect" to detect motion and trigger proximity alerts. So, before understand how the RCWL-0516 sensor works, let’s understand the Doppler Effect. The Doppler effect, is named after the Austrian physicist Christian Doppler, who described this phenomenon in 1842. He described the change in frequency observed by a stationary observer when the source of the frequency is moving. The sound's pitch is higher than the emitted frequency when the sound source approaches the observer as the sound waves are squeezed into shorter distance (bunched together), which can be heard as a higher pitch. The opposite happens when the object moves away from the observer, causing the sound waves to become lower in frequency and lower in pitch (spread out). As a result, the observer can hear a noticeable drop in the pitch as it passes. This holds true for all sorts of waves, such as water, light, radio, and sound. How Does The RCWL-0516 Works? Like the PIR Sensors, these sensors also detects only movements within their detection range. But instead of sniffing the blackbody radiation of a moving object, these sensors uses a “Microwave Doppler Radar” technique to detect a moving object. Doppler microwave detection devices transmit a continuous signal of low-energy microwave radiation at a target area and then analyze the reflected signal. The target’s velocity can be measured by analyzing how the target’s motion altered the frequency of the transmitted signal. Due to Dopplers effect, the frequency of reflected microwave signal is different from the transmitted signal when an object is moving towards or away from the sensor. When a car approaches a speed trap radar, the frequency of the returned signal is greater than the frequency of the transmitted signal, and when the car moves away, the frequency is lower. This is how a speed gun calculates the speed of the car. Technical Specifications The technical specifications of this sensor are listed below: Operating Voltage: 4-28V (typically 5V) Detection Distance: 5-7 Meters Maximum Current Drawn: ~ 2.7 mA Operating Frequency: ~ 3.18 GHz Transmission Power: 20 mW (typical)/30 mW (max) Signal length: ~ 2s Regulated Output: 3.3V, 100mA RCWL-0516 Module Pin outs The RCWL0516 module is a single breakout board with the following connections: 3V3 : it is the "output" from the onboard 3.3V regulator which can be used to power external circuits. Remember, this is not an input pin. This pin can provide up to 100mA of current. GND : is the ground pin. OUT : is the 3.3V TTL logic output. This pin goes HIGH for 2seconds when a motion is detected and goes LOW when no motion is detected. The output of this module is "analog" and can be connected to an analog input of a micro controller and sampled by an ADC. The output voltage is roughly proportional to the distance between the sensor and the object. VIN : provides power to the module. Connect this pin to an input voltage anywhere between 4 to 28V (however, 5V is commonly used). This module consumes less than 3mA of current so, you can easily power this by the 5V output from an Arduino or a Raspberry Pi. CDS : pins are where you attach an optional LDR (light dependent resistor) allowing it to operate only in the dark. You can connect the LDR to the sensor in two ways: * By using the two CDS pads on the top of the module. * Or by connecting one end of the LDR to the CDS pin at the terminal end, and the other end to the ground. We will cover this in the details in the demo section. Remember, this module comes without any connecting pins attached to it. What does CDS stand for? CDS stands for Cadmium Sulphide, which is the photoactive component in LDRs. Because of this, LDRs are sometimes called CDS photoresistors. The RCWL-9196 IC Unlike the PIR sensor, this is an active sensor (Active sensors send out a pulse of energy and detect the changes in the return signal). The module sends out microwaves signals actively at a frequency of about 3.18 GHz and measures the reflected signals. The heart of the module is a doppler radar controller IC "RCWL-9196". This IC is very similar to the BISS0001 IC found in the PIR sensors. The chip also supports "repeat triggers" and has a "360-degree detection area without blind spots". Microwave Antenna and RF Power Amplifier The MMBR941M RF amplifier is a high-speed NPN transistor "Q1" that takes low-power RF signal and boosts it to a higher power level. The antenna is integrated on the PCB. It has a detection range of approximately "7 Meters" while only consuming less than "3mA of current". When triggered, the output (OUT) pin will switches from LOW (0V) to HIGH (3.3V) for 2 to 3 seconds before returning to its idle (LOW) state. The transistor Q1 also acts as a mixer that combines the transmitted and received signal and outputs the difference which is filtered by the low pass filter formed by C9 and R8, and is amplified by the IC. Jumper Settings The module has 3 jumper settings at the back of it. The sensors default settings can be altered, by populating these jumpers with appropriate resistors and capacitors: C-TM : (Pulse length Adjustment) By installing a suitable SMD capacitor you can adjust the repeat trigger time by extending the output pulse length. Default trigger time is 2s. Increasing capacitor's capacity will make repeat trigger time longer. A 0.2µF capacitor extends the output pulse to 50s, while 1µF extends it to 250s. R-GN : (Detection Range Adjustment) By installing a suitable resistor you can reduce the detection range. The default detection range is 7m. If you install a 1M resistor the distance reduces to 5m, while a 270K resistor reduces it to 1.5m. R-CDS : (Light Sensitivity Adjustment) You can use this as an alternative to soldering the LDR. Any resistor between 47K – 100K will suffice. The lower the value, the brighter the light must be in order to disable the trigger. Demo Demo 1: Basic Setup This sensor is capable of working on its own even without a microcontroller. In my first example I am going to show you guys how useful it is on its own. The wiring is very simple, you just need to connect the sensor's VIN and GND to a power supply between 4-28V. Then connect a LED to the OUT pin via a 220Ω current limiting resistor. That’s it, as easy as that. Now, when the module senses motion, the red LED lights up for about two seconds when the OUT pin of the sensor goes “HIGH”. You can replace the LED with a relay module if you want to turn something ON/OFF based on motion. Demo 2: Connecting an LDR The setup is exactly same as the previous one with an addition of an LDR. As discussed earlier, you can either connect the LDR to the two CDS pads on the top of the sensor, or attach one leg of the LDR to the CDS pin at the bottom of the module and the other one to GND. LDRs don't have polarity, so they can be connected in any direction of your choice. When the LDR is exposed to light the resistance of the LDR decreases, and you will notice that the sensor produces no output. However, the sensor resumes normal operation once the room is darkened. This property of the sensor can be used in spotting intruders at night or controlling lights in a room. Demo 3: Connecting an Arduino While this module works well on its own, it also works well as a sensor when hooked up to a microcontroller or a microcomputer. In this example, I am going to light up an LED using an Arduino when the sensor senses a motion. Power the sensor from the 5v pin of the Arduino and connect the OUT pin to pin 2 of the Arduino. Now, connect an LED to pin no 3 of the Arduino via a 220Ω current limiting resistor. Upload the code and swipe your hand over the sensor. The red LED lights up and the serial monitor displays the message "Motion Detected" when the sensor detects a motion. Demo 4: Sending Motion Alerts Over RF or WiFi You can do all sorts of funky stuff using this sensor. You can attach this module to a nodeMCU or a NRF20L01 transceiver module or to a 433MHz RF transmitter/receiver module to send the detected motion information as a notification to a mobile device or save it in a database. Advantage and Disadvantages Advantages Very cheap and compact. The PCB itself is less than 4mm thick They can penetrate through walls and holes allowing them to have a wide detection range Radar signals can penetrate non-conductive materials such as plastic and wood allowing them to be hidden or protected from accidental damage These sensors can work perfectly behind 18mm thick pieces of pine wood, 50mm thick hardback book with no obvious reduction in sensitivity These sensors are safe. They put out very low levels of microwaves at 3.2GHz They are not effected by heat much and have better detection rate than traditional IR sensors They are incredibly sensitive to movement and can detect small movements very easily Disadvantages Since these sensors rely on a Doppler radar system, signal reflections from other nearby objects can interfere with the measurement, making it less reliable and accurate than other sensors These sensor and all its leads needs to be rigidly mounted. If the connecting leads are subject to movement or vibration, they will trigger the sensor These sensors don't work behind normal standard double glazing panels The reflections from metals can also influence the measurements They can be triggered by the wind You can use Aluminum foils to block the microwave signals from the sensor Uses Burglar alarm Intruder detection Smart security devices Human sensing toys Geofencing Halloween props Sensing people/animals through walls even without light Security and motion sensing light switches Thanks Thanks again for checking my post. I hope it helps you. If you want to support me subscribe to my YouTube Channel: https://www.youtube.com/user/tarantula3 Video: Visit Full Blog Post: Visit Code: Download Datasheet: Download Schema: Download Other Links: PIR Sensor Tutorial - With or Without Arduino: YouTube DIY Relay Module: YouTube All About nRF24L01 Modules: YouTube DIY - NodeMCU Development Board: YouTube Contactless Wireless Door Bell Using Arduino: YouTube Doppler Effect: Wikipedia Support My Work BTC: 1Hrr83W2zu2hmDcmYqZMhgPQ71oLj5b7v5 LTC: LPh69qxUqaHKYuFPJVJsNQjpBHWK7hZ9TZ DOGE: DEU2Wz3TK95119HMNZv2kpU7PkWbGNs9K3 ETH: 0xD64fb51C74E0206cB6702aB922C765c68B97dCD4 BAT: 0x9D9E77cA360b53cD89cc01dC37A5314C0113FFc3 LBC: bZ8ANEJFsd2MNFfpoxBhtFNPboh7PmD7M2 COS: bnb136ns6lfw4zs5hg4n85vdthaad7hq5m4gtkgf23 Memo: 572187879 BNB: 0xD64fb51C74E0206cB6702aB922C765c68B97dCD4 MATIC: 0xD64fb51C74E0206cB6702aB922C765c68B97dCD4 Thanks, ca gain in my next tutorial.