What is a voltage divider circuit

A voltage divider network is a fundamental electronic circuit used to divide a voltage into smaller fractions. It consists of two or more resistors connected in series or in a string, which create intermediate voltage points between the supply voltage and ground. Voltage dividers are commonly used for various purposes in electronics, including setting reference voltages, biasing transistors, and creating level-shifting circuits.

The basic principle of a voltage divider is based on Ohm’s law, which states that the current through a resistor is directly proportional to the voltage across it and inversely proportional to its resistance. In a voltage divider, the ratio of the resistance values determines how the input voltage is divided between the resistors.

Mathematical Formulation:

The output voltage (Vout) of a voltage divider can be calculated using the formula:

Vout=Vin×R2R1+R2

Where:

  • Vin is the input voltage applied across the voltage divider.
  • R1 and R2 are the resistance values of the two resistors in the divider.

Applications of Voltage Divider Networks:

  1. Voltage Level Shifting: Voltage dividers can shift the voltage level of a signal. For example, they are used in resistor networks to adjust signal levels for compatibility between different parts of a circuit.
  2. Reference Voltage Generation: Voltage dividers are used to generate reference voltages for analog-to-digital converters (ADCs) and digital-to-analog converters (DACs).
  3. Biasing Transistors: Voltage dividers are commonly used in transistor biasing circuits to set the base or gate voltage of the transistor.
  4. Sensors and Measurement: Voltage dividers are used in sensor circuits to measure changes in resistance, capacitance, or other properties.
  5. Potentiometers: A potentiometer is a variable resistor used in voltage divider configurations to provide adjustable voltage outputs.
  6. Signal Attenuation: Voltage dividers are used to attenuate or reduce the amplitude of a signal while maintaining its shape.
  7. Zener Diode Voltage Regulation: Voltage dividers in combination with Zener diodes can be used to regulate voltage levels.
  8. Low-Power Applications: Voltage dividers are often used to create low-power biasing networks in energy-efficient circuits.

Considerations:

While voltage dividers are versatile and widely used, there are a few considerations to keep in mind:

  • Voltage dividers are sensitive to changes in load impedance. A significant load can affect the accuracy of the divided voltage.
  • Current flowing through the divider results in power dissipation in the resistors. Ensure that the power rating of the resistors is sufficient to handle the current and prevent overheating.

In summary, voltage divider networks are a fundamental and versatile circuit arrangement that finds application in a wide range of electronic systems and components. Understanding how to design and use voltage dividers is essential for effective circuit design and analysis.

Factors affecting Wi-Fi transmission range

The range of a Wi-Fi signal can be influenced by several factors, which can impact its coverage and strength. Understanding these factors can help you optimize your Wi-Fi network for better performance. Here are the key factors that affect Wi-Fi transmission range:

  1. Frequency Band: Wi-Fi operates in different frequency bands, such as 2.4 GHz and 5 GHz. The 2.4 GHz band has better range but can be more susceptible to interference, while the 5 GHz band offers faster speeds but has a shorter range due to higher frequencies.
  2. Obstacles and Interference: Physical obstacles like walls, floors, furniture, and appliances can weaken Wi-Fi signals. Interference from other electronic devices, microwave ovens, cordless phones, and Bluetooth devices operating in the same frequency range can also degrade signal strength.
  3. Signal Strength and Transmit Power: A stronger signal from the router’s antennas results in better coverage. Routers with higher transmit power can extend the range, but there are legal limitations on maximum transmit power.
  4. Antenna Design and Orientation: The quality and design of antennas in both the router and client devices play a crucial role in signal propagation. Positioning antennas for optimal line-of-sight and orientation can improve coverage.
  5. Number of Access Points: Deploying additional access points or Wi-Fi extenders can help expand coverage, especially in larger spaces.
  6. Wi-Fi Standards: Newer Wi-Fi standards like 802.11ac (Wi-Fi 5) and 802.11ax (Wi-Fi 6) provide better range and performance compared to older standards.
  7. Data Rate and Modulation: Lower data rates and less advanced modulation schemes can achieve longer range at the expense of speed.
  8. Channel Width: Wider channel widths (e.g., 40 MHz, 80 MHz) provide higher speeds but can reduce range due to increased susceptibility to interference.
  9. Noise and Signal-to-Noise Ratio (SNR): Higher levels of background noise can decrease the SNR, affecting the ability of devices to communicate over longer distances.
  10. Router Placement: The location of your router matters. Placing it in a central position and avoiding dense obstructions can improve signal distribution.
  11. Wi-Fi Interference: Overcrowded Wi-Fi channels in densely populated areas can lead to interference and reduced range. Selecting less congested channels can help.
  12. Environmental Conditions: Weather conditions, humidity, and atmospheric factors can affect signal propagation, particularly in outdoor or open environments.
  13. Client Device Quality: The quality and design of Wi-Fi antennas in laptops, smartphones, and other devices can impact their ability to receive signals at longer distances.
  14. Firmware and Settings: Keeping router firmware up to date and configuring settings like transmission power, channel selection, and QoS (Quality of Service) can influence range and performance.
  15. Security Settings: Certain security features like WPA3 can enhance both security and range by improving the efficiency of data transmission.

Optimizing your Wi-Fi network involves considering these factors and making adjustments to your router’s placement, settings, and hardware as needed to ensure the best possible coverage and performance throughout your space.

Unveiling the Power of Open Source Hardware: A Collaborative Innovation Frontier

Introduction

In an era characterized by rapid technological advancements and a growing emphasis on collaboration, open source principles have transcended the realm of software and made an indelible mark on hardware development. Open source hardware (OSH) represents a paradigm shift in innovation, fostering a community-driven approach that democratizes access to technology and enables a more inclusive, creative, and sustainable future.

Defining Open Source Hardware

Open source hardware refers to the design and sharing of physical products, devices, and systems in a manner that allows anyone to view, modify, distribute, and even manufacture the technology. Similar to open source software, OSH is built on principles of transparency, collaboration, and user empowerment. The core idea is to provide the necessary information, such as schematics, blueprints, and design files, to enable others to replicate, customize, and contribute to the development of hardware projects.

Key Characteristics of Open Source Hardware

  1. Transparency: OSH projects make their design documentation openly accessible, ensuring that anyone can scrutinize, learn from, and improve upon the technology. This transparency promotes accountability and enables collective learning.
  2. Collaboration: OSH thrives on collaboration, encouraging a diverse community of enthusiasts, developers, and experts to collaborate on refining and enhancing hardware designs. This collaborative spirit often results in faster innovation and a higher quality of products.
  3. Customization: With OSH, users are not limited to a one-size-fits-all solution. They can modify, adapt, and tailor hardware designs to suit specific needs or preferences, promoting flexibility and versatility.
  4. Education: OSH projects provide an invaluable educational resource, allowing students, hobbyists, and professionals to learn about electronics, mechanics, and engineering by studying and tinkering with real-world designs.
  5. Affordability: By sharing designs and encouraging local manufacturing, OSH has the potential to reduce costs associated with proprietary hardware, making technology more accessible to a broader audience.

Advantages of Open Source Hardware

  1. Rapid Innovation: The collaborative nature of OSH accelerates innovation cycles, as countless minds contribute to refining and expanding upon designs. This leads to quicker development and more frequent breakthroughs.
  2. Global Access: OSH transcends geographical boundaries, enabling individuals and communities around the world to access and contribute to technology, bridging the digital divide.
  3. Reduced E-Waste: OSH promotes repairability and upgradability, contributing to a reduction in electronic waste by extending the lifespan of devices and encouraging responsible consumption.
  4. Community Empowerment: OSH projects foster a sense of community ownership and engagement. Local groups can come together to address unique challenges, leading to localized solutions.

Notable Open Source Hardware Projects

  1. Arduino: A popular open-source electronics platform based on easy-to-use hardware and software. Arduino has empowered countless inventors, artists, and students to create interactive projects.
  2. Raspberry Pi: A low-cost, credit card-sized computer that has sparked a revolution in DIY computing and education. Its open design has led to an expansive ecosystem of projects.
  3. OpenROV: An open-source underwater robot that enables exploration of aquatic environments. It serves as a tool for marine scientists and hobbyists alike.
  4. Open Source Ecology: Dedicated to the creation of open source industrial machines that can be used to build sustainable communities, this project encompasses everything from tractors to 3D printers.

Challenges and Future Outlook

Despite its numerous benefits, OSH also faces challenges, such as ensuring high-quality documentation, managing intellectual property, and sustaining long-term development. However, as OSH continues to gain traction, it has the potential to reshape industries, facilitate interdisciplinary collaboration, and democratize access to technology in unprecedented ways.

Conclusion

Open source hardware represents a remarkable convergence of innovation, collaboration, and democratization. By breaking down barriers to entry and enabling a diverse global community to contribute to technology, OSH is poised to drive profound changes in the way we design, create, and interact with hardware. As the world continues to embrace open source principles, the horizon of possibilities for open source hardware remains bright and limitless.

How to use a relay

A relay is an electrically operated switch. Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. The coil current can be on or off so relays have two switch positions and they are double throw (changeover) switches.

The relay’s switch connections are usually labeled COM(POLE), NC and NO:

COM/POLE= Common, NC and NO always connect to this, it is the moving part of the switch.

NC = Normally Closed, COM/POLE is connected to this when the relay coil is not magnetized.

NO = Normally Open, COM/POLE is connected to this when the relay coil is MAGNETIZED and vice versa.

A relay shown in the picture is an electromagnetic or mechanical relay.

Fig. Relay and its symbol

There are 5 Pins in a relay. Two pins A and B are two ends of a coil that are kept inside the relay. The coil is wound on a small rod that gets magnetized whenever current passes through it.

COM/POLE is always connected to NC(Normally connected) pin. As current is passed through the coil A, B, the pole gets connected to NO(Normally Open) pin of the relay.

Here is an example,

First of all try the following circuit.

This is a dark sensor circuit.

Fig. Dark sensor using two transistors

Output of this circuit: When you block light falling on LDR, the circuit switches on the LED- D1.

Now, replace LED-D1 and R2- 330R with a relay and diode.

Reconfigure the circuit as shown in the figure below:

Note: In R3, you can keep any resistor from 330R to 4.7K, this resistor is for sensitivity of the dark sensor.

The following circuit also works as a dark sensor. When you block light falling on LDR, the relay gets activated and Pole of relay gets connected to NO pin that eventually gives power to LED- D1.

dark sensor

 

Fig. Dark sensor using two transistors and a relay.

Light sensor using relay and transistors

In this case, the configuration of relay has been changed. Here, NO (Normally open) terminal has been left open. In normal case, the D1-LED remains ON. When light falling on LDR is interrupted, pole of relay gets connected to NO terminal. Hence, NC (Normally connected) terminal does not get power and that switches the D1- LED off.

dark sensor 2

Fig. Light sensor using two transistors and a relay.

Connect to COM(pole) and NO if you want the switched circuit to be on when the relay coil is on.

Connect to COM(pole) and NC if you want the switched circuit to be on when the relay coil is off.


WORKING WITH 220V

WARNING: IF YOU ARE A NOVICE DO NOT PLAY WITH 220V AC. CALL AN EXPERIENCED PERSON FOR ASSISTANCE.

Fig. Dark sensor circuit for 220V powered lights.

A relay can be used to turn on lights working on 220V, AC. The AC powered light has to be connected to relay as shown in the picture above.

Fig. Connecting wires on relay

The following video shows a soldered/finished prototype.

PROTECTION DIODE FOR RELAY

dark sensor 3

Fig. Protection diode in the circuit

Transistors and ICs must be protected from the brief high voltage produced when a relay coil is switched off. The diagram shows how a signal diode (eg 1N4148 or 1N4001 or 1N4007) is connected ‘backwards’ across the relay coil to provide this protection.

Current flowing through a relay coil creates a magnetic field which collapses suddenly when the current is switched off. The sudden collapse of the magnetic field induces a brief high voltage across the relay coil which is very likely to damage transistors and ICs. The protection diode allows the induced voltage to drive a brief current through the coil (and diode) so the magnetic field dies away quickly rather than instantly. This prevents the induced voltage becoming high enough to cause damage to transistors and ICs.

GENERAL SPECIFICATION OF A RELAY

06VDC- means that the voltage across the relay coil has to be 6V-DC.

50/60Hz- The relay can work under 50/60Hz AC.

7A, 240VAC- The maximum AC current and AC voltage specification that can be passed through NC, NO and pole pins/terminals of relay.

One more example (update 19.3.2014)

relay 2

05VDC- It means that you need 5V to activate the relay. In other words, it means that the voltage across the relay coil has to be 5V-DC.

10A 250VAC     10A  125VAC  – The maximum AC current and AC voltage specification that can be passed through NC, NO and pole pins/terminals of relay. Some countries have 220V AC power standard, so, it works in those countries also.

10A 30VDC   10A 28VDC- The maximum DC current and DC voltage specification that can be passed through NC, NO and pole pins/terminals of relay.

Tips:

– If you are using a 5-6V relay, use a 6V power supply.

– If you are using a 9V relay, use a 12V power supply.

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