I wish electronic hobbyist all over the world can deploy electronics in all possible way, so that they can help mankind to fight this pandemic.

Jumbo Sanitizer

This is not new that at the time of crisis, when nothing works, nothing arrives in time from the online stores, the great Indian ‘jugad technology’ or improvisation gives us a great sigh of relief. Well, I shall not Indianize it fully, nonetheless it works everywhere in every possible way and ‘jugad electronics’ too falls in that line.

When the total lock down-2 started, nothing was available even for making hand rub sanitizer, the denature grade alcohol was not available in sufficient quantity for giving supply to all the departments and we had to wait for few days to get the first truck full of supply to land at our premises.

Since then we have been supplying hand-rub sanitizer to all the departments, communities even a good amount was delivered to the district administration as well. The axiom is same – you be safe & well so that we too remain safe & well. we believe it to the core and this time is the time of testimony for all that...

The demand was since the beginning for every department including the project hospital – contactless sanitizer for the common area.

We tried for the readymade Indian stores – amazon, ebay, deal extreme but none were capable to deliver due to prolonged lockdown. In fact, they were all cancelling their existing orders due to inability of the delivery services.

Therefore, we rolled our sleeves and built a few prototypes of jumbo sized hands-free-sanitizers. The basic parts we mostly salvaged from the exhausted hand wash bottles – pipes, spray nozzles and a big hard top can / jar.

And we built our first working hands-free sanitizer.

The main container is a big hard top jar which we salvaged from a popular food suppliment jar of a popular company. After making a small hole on the cover, we inserted the spray nozzle which we salvaged form a liquid hand wash dispenser [pic]. Next we attached the pump and rolled up the rubber pipe upto the of the shoulder of the nozzle as shown in the picture below.


Now dip the assembly into the big can and through another hole the motor supply to be taken out. Once, you reach upto this, the remaining is just a cat walk. The electronic is the easiest & the most clever portion of this whole project.

Spray principle: The pump is ready and submerged into the liquid Sodium Hypochlorite [sanitizing agent]. The nozzle mouth is also connected with the pump discharge. The nozzle mouth may be jammed little bit with small jammers [like rubber piece, ball point pen tube etc.] to reduce the spray quantity. Now we have to make the pump running when some body brings his / her hands in less than 15 cm of the nozzle. To achieve that there are many electronic ways – Infrared proximity sensor, Doppler sensor, ultrasonic sensor etc.

Accessories: We choose HC-SR04 based ultrasonic distance measuring proximity sensor because I have quite few of these sensors available right now. Also time is the main essence. If I order others, it would not arrive soon due to the lock down effect! However, if you understand one principle, you will be able to engage any other sensor that you find in your way! The small pump which I purchased quite a few for USD1.5 a piece now suddenly becomes the most sought-after ingredient for this project!

Microprocesor : I have variety of cheap microprocessors for the job but the cheapest one is ATMEGA328 – Arduino. Instead of deploying a full Arduino board if one can deploy just the ATMEGA328 chip [Arduino on board], the cost & size will be further reduced.

Pump: We understand thatthere are variety of pumps to cater for this project. To tackle the problem we have used ground switching by deploying an NPN power transistor [2N2219]. In case you have a pump of higher rating just connect the ground to the common ground of Arduino and the higher positive supply [6volt, 9 volt, 12 volt or 24 volt] to the pump positive supply and it will work.

Power supply unit: This completely depends on the pump voltage rating. If it’s a 3v~6V rated pump then a common smart phone charger will work jolly well.

BOM: [Jumbo Sanitizer]1. A good quality hard top jar. Transparent jar is a better choice.2.DC submersible pump [3 volt to 12 volt]. The aliexpress.com is asking for hefty P&F charges. Search your country’s local sources. It must be cheaper there.3. Ultrasonic sensor [HC - SR024] – USD2. Search your local sources. IT’s very common.4. An Arduino on board. USD2. Search your local sources. IT’s very common.5. 2N2219 Transistor, Regulator IC7805, LEDs, IN60 diode Power supply unit / 5Volt SMPS, wires, rubber pipes, fixtures etc are all very common.


Testing: After assembling everything on a general purpose PCB, fix it on the jar top with glue gum or sticker pads. Keep the face of the HC-SR04 close to the nozzle mouth. Now put on the adapter power supply or 12V battery power supply and bring your palm close to the nozzle, the motor should start and the liquid should come out immediately. Since the piping quantity is negligible and the motor passage is very narrow, there will be hardly any airlock after first start such that the spay will never be delayed. The proximity limit is set as 15 cm which can be adjusted in the sketch.

Aftermath: I wish electronic hobbyist all over our country can deploy electronics in all possible way, so that they can help mankind to fight this pandemic..Once you know the technique described here ,you can replace the pump by a solenoid operated water line valve such that it will be converted into a touch less wash basin tap...

I have more demand of hands-free sanitizer now to meet… lol

S. BeraVindhyanagar - 02/04/2020