Hello there electronic enthusiasts and hobbyists. In one of our previous Blog we made a DIY Arduino hand sanitizer dispenser and donated it to a Bank later. That project was made under limited resources but was totally functional, yet I wasn’t satisfied with that project. So today in this blog we will make a much more efficient version of touch-less sanitizer dispenser. We will learn to design the circuit which is based on pure electronics, later order that circuit using an Online PCB Manufacturing Service. At Last we will bring it all inside a beautiful enclosure and mount it on our Front Door, so it can be used every time someone enters.

Supplies

Electronics:

PCB( Gerber can be found in further steps )
IC LM358.
IC base (8 pin).IR LED.10K ohm resistor. - 2
330 ohm resistor. - 3
Screw Terminal - 2
3MM LED - 2
6V DC Submersible Pump.
9V Power Supply

Tools:

Step 1: Watch the Video!

Step 2: Ideology

First let’s discuss the basic idea of this Project and then we will discuss specific components or systems. The Basic Goal of this Project is to Dispense Alcohol Hand Rub or Say Hand Sanitizer without Touching the Bottle, for which we will need a Sensor, a device that can understand sensor data and translate it to something that can be used to mechanically dispense the Alcohol Hand Rub or Hand Sanitizer.

Step 3: Understanding the Electronics

For Sensor, we have a lot of options like IR Sensor, Proximity Sensor, Ultra Sonic Sensor, even Radio Proximity sensors can be used. All of them have their own Advantages and Disadvantages, yet the best and cheapest option would be IR Sensor, which due to super high demand is either out of stock or over priced. So i chose to make my own circuit. I figured out this circuit starting with IC LM393, which is basically a comparator IC. After looking at the datasheet and connections closely, it was clear that the circuit is a classical Voltage Comparator which compares IR receivers Voltage with a Reference voltage from pot, and that is simply brilliant. After reverse engineering, I tried this circuit on a Breadboard only to find out the output current isn’t even sufficient to Drive MOSFET which will make this circuit useless. Rather than giving up, I searched for alternatives and found this comparator IC LM358. The datasheet of LM358 showed us an example of Voltage Comparator, which I used to create my own schematic, the only extra thing I will add in this circuit is a MOSFET to drive high currents typically upto 44 Amps. I made a test circuit on breadboard, which worked perfectly to my surprise.

Well, in our previous Project, we used Arduino as brains. It processed the Input from ultrasonic sensor and gave output to servo, which won’t be necessary this time, since we have a digital High or Low Output unlike digital code pulse from Ultrasonic which needed computation to indicate distance.

( Refer to Circuit Diagram and Data sheet in this step)

Step 4: Mechanical Dispension

for Mechanical dispension action, we could use servo, but again it is not the most efficient way, so in this build we will use a Submersible Pump, which will stay inside tank to pump out Sanitizer. the pump we are using is a 6v pump and it is completely sealed so there are least chances of burning or damaging. Now conclusively we have a Sensor, which can directly drive pump using MOSFET, removing need of Arduino and reducing the overall cost drastically.

Step 5: PCB and Soldering

We will test this already built circuit on breadboard by adding pump to make sure it works as expected. be noted that circuit diagram is attached below with proper labeling. Now it’s time to make a proper PCB, for which I used PCBways online PCB manufacturing service. Ordering a PCB from PCBway is very simple, just like ordering from amazon. Simply enter dimension of PCB as 40x50mm double layer and 1.6mm thickness, keep all other parameters as standard and at last upload the gerber File (which you can find HERE!). After receiving the PCB, Place components in given order and solder them, if you are new to Soldering, this Tutorial might help you. After soldering give the circuit a final test run.

Step 6: Finding the Perfect Enclosure

Once our electronics part is done, we will start to bring this project to life. We need a storage tank to store Alcohol Sanitizer or hand rub, for which I found this bottle with Cap wide enough to fit the pump inside. I used Aquarium Tube to get output of pump from dispenser, later made appropriate holes for tubing and wire, and powered everything with a Wall Adapter. You could use batteries to make project portable ( any battery that can output 9V DC ). You can also add a pen end Cap to limit the Flow of Liquid, but be careful don’t use too small hole in the end else you will choke the Motor. Finally, I used Hot-Glue to mount the sensor PCB on underside of bottle. Since I have more plans on upgrading this device, I will use another plastic container so that we have room for improvement for the next project and also it is easy to mount such System on our Front Door. Before we mount it, we will spray this Container with my favourite silver spray. I added a piece of tape to keep one little segment unpainted for sensor. Later on I drilled more holes for pipe and power and at last we will use some bolts to mount this on our door!

Step 7: Conclusion

After mounting everything up, we can conclude this project as success and it’s quite mesmerizing to watch this machine in use. This machine is quite small in footprint plus it looks great and is totally functional. We might modify this project further in some other Blog. Subscribe to not miss that project. Anyway I hope you guys learnt something from this Detailed blog tutorial, and if you enjoyed this blog, make sure to give it a Like, share it with your Friends and Follow us on Social media for more awesome content!

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