Excellent hygiene practices have a long-lasting effect on the positive proclivity of any environment. With the current ongoing global pandemic of the novel Corona Virus or COVID-19, proper hygiene practices especially the cleanliness of one’s hands have become imperative to combat this deadly disease while maintaining a productive work environment. So, in this project, we are going to go over a step-by-step procedure on ‘How To Make A Touchless Hand Sanitizer Dispenser’ using a simple servo motor & sn IR sensor setup.
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Touchless Hand Sanitizer Dispenser
A Touchless Hand Sanitizer Dispenser is an IR sensor-based dispenser & can be used to dispense any alcohol-based sanitizer. It has a touch-less operation, which makes people fearless and more confident about the sanitization process. It is also known as an automatic or contact-less sanitizer dispenser. As per the servo motor’s range of motion, it only allows 1ml of liquid to dispense at one time. In the time of the world pandemic COVID 19, the automatic hand sanitizer dispenser is an essential product to kill the effect of the novel coronavirus.
Hardware Components
The following components are required to make Touchless Hand Sanitizer Dispenser Project
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Rigid wire/zip tie | – | 1 |
| 2. | IC | NE555 Timer | 1 |
| 3. | Op-Amp IC | LM358 | 1 |
| 4. | Relay | SPDT/5V | 1 |
| 5. | Servo Motor | SG-90 | 1 |
| 6. | Dispenser Container with nozzle | – | 1 |
| 7. | IR Emitter LED | 5mm/3.5V | 1 |
| 8. | IR receiver | TSOP1738 | 1 |
| 9. | NPN Transistor | 2n2222 | 2 |
| 10. | LED | 5mm | 1 |
| 11. | Potentiometer | 10K | 1 |
| 12. | Capacitors | 100nF | 2 |
| 13. | Resistors | 10K, 68K, 33K, 4.7K, 1K, 560 Ohm, 220 Ohm | 9 |
| 14. | Soldering Iron | 45W – 65W | 1 |
| 15. | Diode | 1N4007 | 1 |
| 16. | Soldering Wire with Flux | – | 1 |
| 17. | Veroboard | – | 1 |
| 18. | DC Battery with Clip | 9V | 1 |
| 19. | Male Header pins | – | 1 |
| 20. | Jumper Wires | – | As per need |
NE555 IC Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 555 Timer
LM358 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of LM358
Useful Steps
1) Solder the pins 4 & 8 of the 555 timer IC on the Vero board.
2) Solder a 33K Ohm resistance between pin 7 & pin 8 of the timer IC. After that solder a 68K resistor between pins 6 & 7 of the timer IC.
3) Solder two 100 pF capacitors from pin 2 to pin 1 and pin 1 to pin 5 of the timer IC.
4) Solder the emitter of the 2n2222 transistor to pin 1 of the IC. After that, solder a 4.7K resistor between pin 8 & the collector of the transistor.
5) Connect a 1K resistance between pin 3 & the base of the transistor.
6) Solder a 5V relay on the Vero board & solder a 10K resistor between pin 6 & NO terminal of the relay.
7) Solder male headers for servo & LM358 Op-Amp on the Veroboard
8) Solder the 10K pot & a 10K resistor between pins 4 & 3 of the Op-Amp.
9) Solder a 1N4007 Diode between relay coil pins. After that, solder it to the collector of the 2n2222 transistor with an emitter soldered to pin 4 of the LM358 IC.
10) Connect a 220 Ohms resistor from pin 1 of the op-amp to the +ve terminal of the LED & connect a 560 Ohm resistor from pin 1 of the op-amp to the base of the transistor. Connect the LED +ve to pin 1 & -ve to pin 4 of the op-amp.
11) Connect a 220 Ohm resistance on pin 4 of the op-amp.
12) Join the IR transmitter LED & receiver in series.
13) Connect the Vcc & GND for Both ICs. Connect the servo to the headers & test the circuit.
Mounting of the Sanitizer Dispenser
14) Mount the circuit on the sanitizer container with the IR sensor pointing in the face direction of the nozzle. Connect a rigid wire or zip tie with the arm of the servo, going over the nozzle of the sanitizer.
Working Explanation
To operate this contactless hand sanitizer, you simply need to reflect the IR rays on the receiver by using your hands, the receiver feeds the output to the inverting input of the op-amp. The op-amp generates an amplified output with respect to the preset of the 10K pot. The output of the op-amp acts as the control signal to the base of the 2n2222 transistor. The resultant collector output picks the coil of the relay & makes the connection to the 555 timer circuit.
The output of the SPDT relay, connected to the TRIG pin of the 555 timers IC results in an output that goes to the base of the second 2n2222 transistor. The collector output toggles the signal pin of the servo & triggers the motion of the servo, allowing a precise amount of sanitizer liquid (1ml) to be dispensed from the container unit.
Applications
- It is an important tool to maintain personal hygiene in places such as schools, hospitals, workplaces, factories, etc.
