DIY Automatic Hand Sanitizer

Due to Covid-19 situation all across the world people everywhere are trying their best to maintain social distancing, hygiene and cleaning their hands as frequently as possible.

For cleaning hands soap and water is very good solution but for those who do not want to get their hands wet again and again Alcohol based sanitizers are being used. Arduino based hand sanatizer are being made to automate dispensing of hand sanitizers.

I really loved a low cost non-controller based Automatic Hand Sanitizer proposed by Techbuilder on youtube. You can develop your own low cost hand sanitizer dispenser by checking out this video. You can even use liquid soap instead of alcohol based hand sanitizers for keeping your hands clean.

In this above video you can see how simply they have made the Automatic Hand sanitizer. The main electronic components that they have used are:

• IR Proximity Sensor

The IR Proximity sensor is a low cost sensor this sensor is extensively used in robotic projects for obstacle sensing or for making a line following robot. The main advantage of proximity sensor is its low cost but the issue with this sensor is it gets affected by sunlight. So your dispenser may not work if it is kept outdoor. Other effective solution to this low cost sensor is using E18-D80 Proximity sensor. The E18 Sensor has sensing range upto 50 cm which can be easily adjusted. The advantage of this E18 sensor is that it can work in direct sunlight.

• 3-6 Volt DC Pump

This is submersible DC pump which are very commonly used in small decorative fountains. These pumps are very simple to use and work on wide voltage from 3 volts to 6 volts. Lot of people are providing 9 volts or even 12 volts the pump may work on 9 & 12 volts but the life of the pump will decrease drastically. I would suggest providing 5 Volts to get good pressure as well as better life.

We tested and found out this pump consumes upto 300 – 400 ma continuous current at 5 volts. Whereas the peak start current can be upto 700 ma in some cases.

• Transistor TIP32C

TIP32 C is a PNP Power transistor and is intended to use in medium power switching applications. TIP32C transistor has peak collector current of 5 Ampere and continuous current of 3 Ampere. Some people are facing the problem that the pump is continuously on and when when the hand is detected the pump stops. In such a case the output of the sensor is normally low and becomes high when the hand is detected so in such a case you will have to use a NPN transistor like TIP31C instead of TIP32C. So basically There are two types of IR sensor module in the market, one type works with NPN transistor (TIP41/TIP31) and other type works with PNP transistor (TIP42/TIP32).

Since the start of the Covid-19 issue lot of students, hobbyist & manufacturers have started using TIP32C transistor in India due to which there has become a shortage for TIP32 transistor. Here are few alternative that we have tested that you can use:

• TIP42C

This is also a PNP transistor with a peak current of 10 ampere and continuous current of 5 Ampere. TIP42 transistor is overkill but it works and if you have nothing else you can use it.

• TIP122

• BD140

• Resistor

A 1K resistor is used in between the proxy sensor and the transistor to limit the base current. You can even use 1.2 K or 1.5 K we had tried 2.2 K and it worked properly.

• 5 Volt Power Supply

Not all 5 volt mobile chargers can be used. We tried the Original Samsung charger that we had with 5 volt output and 1.5 amp peak current still the pump wouldn’t start. So instead we tried with a local low cost charger with peak current of 600 ma and it worked like a charm.

All parts required to make Automatic Hand sanitizer or Soap dispenser are available with us and you can place order from anywhere in India. We are located in Nashik, Maharashtra so all customers in and around Nashik can directly purchase from our shop at Thakker Bazzar, New CBS.