Touch less doorbells can operate without touching the switch
One of the most effective ways to escape from COVID-19 is through social isolation. Staying at home is strongly recommended in the beginning days. However, we still have to make some emer…
Know the mission before touching a wire.
Understand what you are making, prepare the right tools, and make the workbench safe.
Project details
Touch less doorbells can operate without touching the switch is a arduino project. One of the most effective ways to escape from COVID-19 is through social isolation. Staying at home is strongly recommended in the beginning days. However, we still have to make some emer…
- Source pages
- 652-654
- Named parts
- 5
- Build goal
- Working, tested prototype
Tools you need
- Digital multimeter
- Wire stripper and side cutters
- Soldering iron with a fine tip
- Current-limited bench supply
- Computer with a data-capable USB cable
Use eye protection, good lighting, and a clean insulated surface throughout the build.
Safety precautions
- Disconnect every power source before changing a connection.
- Check component polarity, pinout, and supply voltage twice.
- Use a current limit for the first power-up.
- Keep liquids, loose metal, and uninsulated wires away from the bench.
Gather, identify, and understand every part.
Use the standardized inventory, then open What's this? to learn each part's role, advantages, limitations, handling, and specifications.
What's this?Image, role, pros, cons, handling & specifications
MODULE LEARNING VIEWArduino Nano
A programmable controller that reads inputs, makes decisions, and drives the project's outputs.
What it does hereIt is the control centre and must use the documented board, pin map, supply, and logic level.
Buy / compare this part ↗Advantages
- Reprogrammable and reusable
- Large learning ecosystem
- Complex behaviour remains changeable
Limitations
- GPIO voltage and current are limited
- Some pins affect boot or communication
- Loads normally need a driver
Handling
- Disconnect power before rewiring
- Avoid static discharge
- Never power motors, relays, or pumps directly from GPIO
Specifications to verify
- Use the exact model, value, package, and rating listed for Arduino Nano; similar-looking parts are not always interchangeable.
- Confirm operating voltage, logic level, pinout, memory, USB interface, and maximum GPIO current.
What's this?Image, role, pros, cons, handling & specifications
Buzzer
An output component turns an electrical control signal into light, sound, motion, switching, or displayed information.
What it does hereIt presents the circuit result or acts on the physical world.
Buy / compare this part ↗Advantages
- Makes system state visible
- Can be tested separately
- Supports clear troubleshooting
Limitations
- Loads may exceed controller current
- Polarity or driver direction can matter
- Inductive loads create voltage spikes
Handling
- Use the documented driver stage
- Check polarity and load current
- Add flyback protection for inductive loads
Specifications to verify
- Use the exact model, value, package, and rating listed for Buzzer; similar-looking parts are not always interchangeable.
- Confirm voltage, current, polarity, interface, driver requirements, and duty cycle.
What's this?Image, role, pros, cons, handling & specifications
Operational amplifier
A named project component whose exact role is defined by the source circuit and build guide.
What it does hereIt performs a documented electrical, control, interface, or construction function in this project.
Buy / compare this part ↗Advantages
- Selected for this project
- Can be checked independently
- Supports modular troubleshooting
Limitations
- Substitutes may differ
- Generic names can hide variants
- Pinouts and ratings vary
Handling
- Compare the received part with the source
- Keep it labelled
- Do not force connectors or adjusters
Specifications to verify
- Use the exact model, value, package, and rating listed for Operational amplifier; similar-looking parts are not always interchangeable.
- Confirm dimensions, ratings, connection method, polarity, and environmental limits.
What's this?Image, role, pros, cons, handling & specifications
IR sensor
A sensor converts a physical condition into an electrical signal the circuit can measure.
What it does hereIt provides project input as an analogue, digital, resistive, frequency, or calibrated signal.
Buy / compare this part ↗Advantages
- Adds real-world awareness
- Can usually be tested independently
- Often supports calibration
Limitations
- Readings can drift
- Placement affects results
- Some sensors need warm-up or calibration
Handling
- Protect the sensing surface
- Observe supply voltage and polarity
- Keep signal leads away from noisy power wiring
Specifications to verify
- Use the exact model, value, package, and rating listed for IR sensor; similar-looking parts are not always interchangeable.
- Confirm supply range, output type, measurement range, accuracy, response time, and pin order.
What's this?Image, role, pros, cons, handling & specifications
SEMICONDUCTOR LEARNING VIEWLM358
A semiconductor stage performs switching, amplification, regulation, rectification, or logic.
What it does hereIt controls current or signal flow at a defined point in the circuit.
Buy / compare this part ↗Advantages
- Fast and efficient
- Compact
- Can control larger loads from smaller signals
Limitations
- Pin order varies
- Sensitive to overvoltage and reverse polarity
- May need cooling or bias components
Handling
- Verify the datasheet pinout
- Avoid static and soldering heat
- Check notch, stripe, or flat-face orientation
Specifications to verify
- Use the exact model, value, package, and rating listed for LM358; similar-looking parts are not always interchangeable.
- Confirm pinout, maximum voltage/current, dissipation, gain or forward voltage, and package.
Connect one verified path at a time.
Explore the named components and standardized signal flow, then use Source Check to verify exact physical pins, values, and topology before applying power.
Trace this circuit.
Touch less doorbells can operate without touching the switch: interactive parts, standardized terminals, responsive anchored wires, student explanations, and the original circuit reference in one shared system.
Trace before wiring
Follow power, ground, inputs, processing, and outputs in that order. Never guess a pin from package shape alone.
Connect with power off
Make short, labelled connections and share a common ground only where the schematic requires it.
Inspect every joint
Check continuity, polarity, adjacent shorts, and loose connections before the first power-up.
Open all source diagrams and build views 2 visuals
Confirm the hardware-only control path.
This project does not include firmware in the source. The circuit itself provides the required behaviour.
How to connect
- Match every controller label to the circuit view and source pin map.
- Join grounds before signal wires when separate low-voltage supplies are used.
- Keep motors, relays, pumps, and other loads on a suitable driver and external supply.
Common mistakes
Reversed VCC/GND, board-label versus GPIO-number confusion, missing common ground, and charge-only USB cables.
Troubleshoot
Disconnect loads, continuity-test one path at a time, then test with a current limit.
Software preparation
No IDE, board package, library, or firmware upload is required for this project.
If you add a programmable controller as an extension, document its pin map separately.
How to upload code
The original design is implemented entirely in hardware, so proceed after verifying the circuit and supply.
Assemble, deploy, test, and troubleshoot.
Use the complete source notes in build order, then pass the final checks before calling the project finished.
Build in functional stages
- Power and regulation
- Controller or processing stage
- Inputs and sensors
- Outputs and loads
- Enclosure and strain relief
Power up safely
- Inspect unpowered continuity first
- Apply the lowest safe current limit
- Measure supply rails before signals
- Add one load at a time
- Record expected and actual results
Work from simple to complex
- Confirm power, ground, polarity, and orientation
- Compare each pin with the source
- Test inputs separately from outputs
- Replace only one variable at a time
- Power off before every correction
Follow the documented instructions.
These notes come from this project's source and remain in their original order.
Project overview
Project build noteOne of the most effective ways to escape from COVID-19 is through social isolation. Staying at home is strongly recommended in the beginning days. However, we still have to make some emergency visits to certain homes. We first searched the doorbell button of a house when we arrived. Then press the doorbell button. However, in this specific situation, this doorbell button can cause the virus to spread. A virus is held on the button when someone who is not infected presses the button, and when a second person touches the button, the virus is spread. A touchless doorbell will help to eliminate this danger. Touchless doorbells are available to convert existing doorbells.
Circuit and working
Project build noteInfrared LED transmitters transmit light within the range of the infrared spectrum. Wave length of IR waves is longer than wave length of visible
light. This transmitted IR light will be picked up by the photodiode receiver. The photodiode will only conduct when it is illuminated. The semiconductor is reverse biased as well. It can be shown that the current flow is directly proportional to the amount of light it receives. In this photo, we see the LM358 Operational amplifier in voltage comparator mode. Comparison is made between the voltage set by the variable resistor and the voltage set by the photodiode series resistor 1. (PSR voltage). A ground connection is maintained between the "OUTPUT" pin and the OP-AMP output. 2. The PSR Voltage has dropped below the Threshold Voltage - the output is HIGH 3. Voltage drops on PSR < Threshold Voltage - Output is LOW 4. By calibrating the variable resistor, the distance at which objects should be detected can be determined.
Key point: In case an object is presented in front of the sensor, the sensor output will be HIGH, but if not, the sensor output will be LOW Essential Components Arduino Nano R3, Relay, IR Sensor, Buzzer A signal will be sent to the Arduino board when we show our hand to the IR Sensor. And Arduino drives the relay. The relay is connected to the doorbell. The bell will ring the moment the relay is activated.
You built Touch less doorbells can operate without touching the switch.
You followed the full workflow from understanding the mission to testing the finished project. That is a real engineering achievement - well done.
Social Distancing Device (Safety Card)
Ready to reuse what you learned in another project from the same track?
Start this project →