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.

Factors affecting Bluetooth transmission range

Bluetooth technology has become an integral part of our wireless communication landscape, enabling a wide range of devices to connect and exchange data. However, the transmission range of Bluetooth connections can vary based on several factors. Here are some key factors that affect Bluetooth transmission range:

  1. Bluetooth Version: Different Bluetooth versions offer varying ranges. The most common versions are Bluetooth 2.1, Bluetooth 4.0 (Bluetooth Low Energy), Bluetooth 4.2, Bluetooth 5.0, and the more recent Bluetooth 5.1 and 5.2. Newer versions tend to offer improved range and better performance.
  2. Signal Strength (Transmit Power): The output power of the Bluetooth transmitter affects the transmission range. Higher transmit power can result in longer range, but it can also consume more energy.
  3. Antenna Design: The design and quality of the antennas used in both the transmitting and receiving devices play a significant role in determining the effective range. Well-designed antennas can enhance the signal strength and coverage area.
  4. Interference and Obstacles: Physical barriers, such as walls, furniture, and other obstacles, can weaken the Bluetooth signal and reduce the range. Additionally, interference from other electronic devices operating on similar frequencies (2.4 GHz) can disrupt Bluetooth communication.
  5. Environmental Conditions: Factors like humidity, temperature, and atmospheric conditions can impact signal propagation. In outdoor settings, Bluetooth range might be affected by weather conditions and terrain.
  6. Device Orientation and Placement: The relative orientation of devices (antennas) with respect to each other can affect signal strength. Positioning devices in a line-of-sight configuration can often result in better range compared to having obstacles between them.
  7. Quality of Receiver: The sensitivity and quality of the Bluetooth receiver in the target device also influence the range. A more sensitive receiver can pick up weaker signals and extend the effective range.
  8. Power Saving Modes: Devices often have power-saving modes that reduce transmission power to conserve energy. These modes can impact range when they are activated.
  9. Frequency Hopping: Bluetooth uses frequency hopping to mitigate interference. The number of hopping channels and the hopping rate can affect the ability to find clear transmission paths, thus influencing range.
  10. Transmission Rate: Higher data transmission rates may result in shorter range due to increased power consumption and a higher probability of data loss over longer distances.
  11. Device Class: Bluetooth devices are categorized into different classes based on their maximum allowable transmit power. Class 1 devices generally have the longest range, followed by Class 2 and Class 3 devices.
  12. Firmware and Software: The firmware and software implementations on both the transmitting and receiving devices can impact the range. Optimized protocols and algorithms can enhance the reliability and reach of Bluetooth connections.

It’s important to note that the actual transmission range can vary significantly based on the combination of these factors. For optimal performance, users should consider the use case, environmental conditions, and device specifications when aiming to achieve the desired Bluetooth transmission range.

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.

CONTACTLESS AUTOMATIC WARDROBE LED LIGHT WITH FADE EFFECT

Contact-less controlled automatic wardrobe light turns on the LED when you open the wardrobe door. Τhe project is based on Hall effect IC including LED driver and tiny magnet. Board doesn’t require any mechanical switch. When magnet is close to the board, LED is off, when you open the wardrobe door magnet goes far from hall IC and its turn on the LED, the IC also has special features like soft start and soft off. This board can be used in other applications like Automotive Gloves boxes and Storage, task lighting, automotive vanity mirrors.  The APS13568 is the heart of the project. The IC can drive LED current up to 150mA. I have set the current 100mA approx. with help of R3. C2 is provided to set the FADE-IN/FADE-OUT time. The value of C2 can be changed as per application requirement.

The IC is an integrated circuit that combines an ultrasensitive, Omni polar, micro power Hall-effect switch with a linear programmable current regulator providing up to 150 mA to drive high brightness LEDs. The Omni polar Hall Effect switch provides contactless control of the regulated LED current, which is set by a single reference resistor R3. This highly integrated solution offers high reliability and ease of design compared to a discrete solution. The Hall-effect switch operates with either a north or a south magnetic pole. The switch output polarity can be set with an external pull down on the POL input pin. This allows the user to select whether the APS13568 switch output goes low when a magnet is present or when the magnetic field is removed. Chopper stabilization provides low switch point drift over temperature. The LED is turned on when the EN input goes low. This active low input can be connected directly to the Hall switch output, SO, to turn the LED on when the switch output goes low. This flexible solution allows the user to connect additional slave switches, LED drivers, PWM, or microprocessor inputs to control when the LED is on. Optionally, an external capacitor can be used to adjust the fade-in/fade-out feature. On-board protection for shorts to ground and thermal overload prevents damage to the APS13568 and LED string by limiting the regulated current until the short is removed and/or the chip temperature has reduced below the thermal threshold. The integrated Hall-effect switch in the APS13568 is an Omni polar switch. The output switches when a magnetic field perpendicular to the Hall sensor exceeds the operate point threshold, BOPx (B > BOPS or B < BOPN). When magnetic field is reduced below the release point, BRPx (B < BRPS or B > BRPN), the device output goes to the other state. The output transistor is capable of sinking current up to the short-circuit current limit, IOM, which ranges from 30 to 60 mA. The difference in the magnetic operates and release points are the hysteresis, BHYS, of the device. This built-in hysteresis allows clean switching of the output even in the presence of external mechanical vibration and electrical noise. Removal of the magnetic field results in an output state consistent with B < BRPx. Since the output state polarity relative to the magnetic thresholds is user-selectable via the POL pin, reference Table 1 to determine the expected output state.

Note: The board has omnidirectional Hall sensor. Default it set to switch on the LED in absence of magnetic field or magnet is not around, it will switch off the LED when magnet is close to the hall sensor IC or in presence of magnetic field. Remove POL Resistor R4 for reverse operation.

FEATURES

  • Supply 12V DC ( 7-24V Supply Possible)
  • LED Current 100mA (LED Current can be set to 150mA with help of R3)
  • Selectable Output Polarity
  • FADE-IN/FADE-OUT ( Soft On/Off)
  • Built In Short Circuit Protection, Thermal Protection, Reverse Battery and Load Dump Protection

SCHEMATIC

PARTS LIST

CONNECTIONS

PHOTOS

VIDEO

PCB

LUX METER MODULE

LUX Meter project has been design to measure the illumination.  Illumination is luminous flux falling on surface area of photo diode.  This illumination converted to corresponding voltage using Op-Amp circuit.

SPECIFICATIONS

  • Supply 9 VDC PP3 Battery @ 20 mA
  •  Onboard Photo Diode
  •  Onboard preset for calibration
  •  Range selection via jumper 10mV/LUX, 1mV/LUX, 0.1mV/LUX
  •  Interfacing is via berg connector
  •  Power-On LED indicator
  •  Four mounting holes of 3.2 mm each
  •  PCB dimensions 53 mm x 38 mm

The project is designed around Texas instrument Op-Amp TLC271 which can operate from single supply with low bias current, here op-amp act as current to voltage converter.  5000 LUX (approx) can be measure with a voltmeter having 5V range.  Meter is not provided.

CALIBRATION

  • J1 Jumper : 10mV/Lux
  • J2 Jumper : 1mV/Lux
  • J3 Jumper : 0.1mV/LUX
  • PR2 Preset : To Calibrate the meter
  • PR1 Preset : Fine Gain adjustment for 10mV/Lux
  • CN1 Connector : Supply 9 VDC (PP3 9V DC Battery Ideal) and Output Voltage
  • D2 LED : Power Indicator
  • D1 LED : Photo Diode (Sensor)

Standard incandescent 100W lamp should be used for approximation calibration.  To make Calibration select the 1mV/Lux J2 Jumper, move the preset full in CCW.  Connect the accurate voltmeter having range of 5V. Adjust the distance between the photo diode and Lamp so that voltmeter reads 0.38V0.  At this point, illumination on photodiode surface is about 100 Lux (aprox).  And then adjust the PR2 so that voltmeter reads 1V.  Calibration has now been complete. This project is based on Hamamatsu Photo Diode Application

SCHEMATIC

LUX_METER_SCH

PARTS LIST

LUX_METER_BOM

 

PCB

DOWNLOADS

SOUND ACTIVATED SWITCH – RELAY

This project is a sound-activated switch.

DESCRIPTION

Clap switch/Sound-activated switch designed around op-amp, flip-flop, and popular 555 IC. Switch avoids false triggering by using a 2-clap sound. Clapping sound is received by a microphone, the microphone changes the sound wave to an electrical wave which is further amplified by the op-amp.

555 timer IC acts as a mono-stable multi-vibrator then flip-flop changes the state of the output relay on every two-clap sound. This can be used to turn ON/OFF lights and fans. The circuit activates upon a two-clap sound and stays activated until another sound triggers the circuit.

Specifications:

  • Supply 12V DC @ 60mA
  • On board preset to set the sensitivity
  • On board LED to indicate the Relay on/off state
  • On board Microphone
  • Relay switch 5Amps, 110V-230V

SCHEMATIC

Sound_Activated_Switch_Top_schematic

PARTS LIST

image description

PCB

PIR SENSOR

This project is an automatic PIR sensor.

DESCRIPTION

Project is based on Holtek’s IC HT7610A, which is a CMOS LSI chip designed for use in automatic PIR lamp, flash or buzzer control. It can operate in 3-wire configuration for relay applications.  In our project we have used relay instead of Traic to connect any kind of load in output, HT7610B IC is suitable for traic and HT7610A for Relay application. The chip is equipped with operational amplifiers, a comparator, timer, a zero crossing detector, control circuit, a voltage regulator, a system oscillator, and an output timing oscillator.

Its PIR sensor detects infrared power variations induced by the motion of a human body and transforms it to a voltage variation. If the PIR output voltage variation conforms to the criteria (refer to the functional description), the lamp is turned on with an adjustable duration. The circuit doesn’t required step down transformer and can work directly by applying 110V AC or 220V AC (Capacitor C7 needs to change for 220V AC (0.33uF/275V) and 110V AC (0.68uF/275V)

FEATURES:

– Supply Input 110V or 220V AC ( Capacitor Value needs to Change)
– No Step Down transformer required
– IC Operating voltage: 5V~12V
– Load Current 80mA when relay is on.
– Standby current of the IC: 100uA
– On-chip regulator
– Adjustable output duration
– 40 second warm-up
– ON/AUTO/OFF selectable by MODE pin
– Override function
– Auto-reset if the ZC signal disappears over 3 seconds
– On Board Relay to connect output Buzzer or Flash
– On Board LDR to Detect Day/Night operation
– J1 to Set the Mode
– PR1 to set the Sensitivity of the sensor
– PR2 to set the output Turn On Duration
– CDS R11 for Auto Day/Night detection
– (HIGH Voltage On Board) Do Not touch the PCB while power is on.

SCHEMATIC

image description

Mode (Jumper J1):

This project offers three operating modes (ON, AUTO, OFF) which can be set through the MODE pin. While the chip is working in the AUTO mode the user can override it and switch to the TEST mode or manual ON mode, or return to the AUTO mode by switching the power switch. J1 Jumper is to set the desired modes.

J1 Jumper Operating Mode Description
VDD ON Output is always On: Output is high RELAY ON
VSS OFF Output is Always Off: Output is low RELAY OFF
Open Open Outputs remain in the off state until activated by a valid PIR input trigger signal. When working in the AUTO
mode, the chip allows override control by switching the ZC signal.

CDS-LDR (Light Dependent Resistor):

CDS is a CMOS Schmitt Trigger input structure. It is used to distinguish between day time and night time. When the input voltage of CDS is high the PIR input is enabled. On the other hand, when CDS is low the PIR input is disabled. The input disable to enable debounce time is 5 seconds. Connect this pin to VDD when this function is not used. The CDS input is ignored when the output is active.

LDR Operations

CDS PIN  (LDR) Status PIR
Low Day Time Disabled
High Night Time Enabled

LDR Operations

OSCD is an output timing oscillator input pin. It is connected to an external RC to obtain the desired output turn-on duration. Variable output turn-on durations can be achieved by adjusting variable resistor or setting various values of RC.

Power-on Initial

The PIR signal amplifier requires a warm up period after power-on. The input should be disabled during this period. In the AUTO mode within the first 10 seconds of power-on initialization, the circuit allows override control to enter the test mode. After 40 seconds of the initial time the chip allows override control between ON and AUTO. It will remain in the warm up period if the total initial time has not elapsed after returning to AUTO. In case that the ZC signal disappears for more than 3 seconds, the chip will restart the initialization operation. However, the restart initial time is always 40 seconds and cannot be extended by adding CRST to the RST pin as shown in the circuit.

The HT7610A offers mask options to select the output flash (3 times) when changing the operating mode. The output will flash 3 times at a 1Hz rate each time it changes from AUTO to another mode and flash 3 times at a 2Hz rate when it returns to the AUTO mode. However the output will not flash if the mode is changed by switching the MODE switch. Options for effective override: Once or twice Off/On operation of power switch within 3 seconds. Options for output flash to indicate effective override operation. Flash for the circuit.

Test mode control

Within 10 seconds after power-on, effective ZC switching will force the chip to enter the test mode. During the test mode, the outputs will be active for duration of 2 seconds each time a valid PIR trigger Signal is received. If a time interval exceeds 32 seconds without a valid trigger input, the chip will automatically enter the AUTO mode

Note:
– The output is activated if the trigger signal conforms to the following criteria:
– More than 3 triggers within 2 seconds
– A trigger signal sustain duration
– 0.34 seconds >/2 trigger signals within 2 seconds with one of the trigger signal sustain 0.16 seconds.
– The effective comparator output width is selected to be 24ms.
– The output duration is set by an external RC that is connected to the OSCD pin

Override control

When the chip is working in an AUTO mode (MODE=open), the output is activated by a valid PIR trigger signal and the output active duration is controlled by an OSCD oscillating period. The lamp can be switched always to ON from the AUTO mode by either switching the MODE pin to VDD or switching the ZC signal by an OFF/ON operation of the power switch (OFF/ON once or twice within 3 seconds by mask option). The term override refers to the change of operating mode by switching the power switch. The chip can be toggled from ON to AUTO by an override operation. If the chip is overridden to ON and there is no further override operation, it will automatically return to AUTO after an internal preset ON time duration has elapsed.

This override ON time duration is 8 hours. The chip provides a mask option to determine the output flash times (3 times) when changing the operating mode. It will flash 3 times at a 1Hz rate each time the chip changes from an AUTO mode to another mode or flash 3 times at a 2Hz rate when returning to the AUTO mode. But if the AUTO mode is changed by switching the MODE switch it will not flash.

PARTS LIST

BOM

PCB

AUDIO VU METER 9 LEDS

5 LED VU Meter kit is based on LB1409 IC from SANYO, which will indicates the volume level of the audio signal it senses

  • SUPPLY 12V DC @ 50mA
  • PR1 REF SET
  • PR2 AUDIO LEVEL SET

SCHEMATIC

schematicPARTS

parts

 

PCB

DOWNLOADS

4 CHANNEL INFRARED REMOTE RELAYS

4 Channel Infrared (IR) Remote controller is using  HT12A and HT12D encoder/decoder chips from Holtek.

FEATURES

  • Supply – Transmitter : 3 to 5 VDC, 5 V @ 20 mA & Receiver : 5 VDC @ 200 mA
  • Output: 4 channel Latch or Momentary onboard Jumper for selection
  • Crystal based oscillator for the reliability of operation
  • Jumper selectable 8-bit address code
  • LED output to indicate reception
  • On/Off slide switch in the transmitter
  • Power-On LED indicator in the Receiver / Transmitter
  • Valid transmission indicator
  • 4 LED for Relay On/Off status
  • Four mounting holes of 3.2 mm each
  • PCB dimensions – Transmitter : 43 mm x 56 mm & Receiver : 80 mm x 73 mm

SCHEMATIC

 

 

PARTS LIST

Receiver BOM

 

Transmitter BOM

VIDEO

PCB

TOGGLE ON / OFF SWITCH

This project describes how to build a “soft touch” switch. By “soft touch” we mean that you have to push once to set device ON and push again to set device OFF. This kind of switch works by latching a relay to ON state with push of a button and with another push latch is released. It is working like flip-flop states. In that way, you can control power to a device using one push button.

The circuit is build around a 555 timer configured in a way that let it latch on one state and an action is required to change state. The circuit is powered from +5V and there are connectors to connect controlling device. Inspiration from this project and circuit is found here: http://todbot.com/blog . We added a relay on output, an indicator led as well as connectors for power, an external push button and relay contacts.

SCHEMATIC

Schematic
The Schematic for this circuit can be seen above. The circuit toggles a relay when button S1 is pressed. Operation of this circuit is simple. Pins 6 and 2 of 555 timer are at half power voltage. When output pin 3 is high then capacitor C1 is charged and when it’s low capacitor is discharged. When button is pressed capacitor voltage appears on pin 6 and 2 and output pin 3 changes state as well as capacitor voltage changes. So when output is high capacitor has +5V. When we press the button pin 3 goes low and capacitor goes 0V, when we press button again output goes high again, so we have toggle functionality. When output is high transistor T1 is conducting current and relay is latched, when low relay is released. Diode D1 is used to protect transistor from back voltage generated when relay goes off.

A disadvantage of this circuit is that when we connect power to the circuit relay is engaged. A solution to this can be found on the second reference website below.

PHOTOS

Photo_2
Circuit is in OFF state
Photo_3
Push button is pressed and circuit goes to ON state. Relay switch on a high power LED

PCB

PCB of Toggle ON/OFF Switch

REFERENCES

PCB

8 CHANNEL RELAY BOARD

This project is a general-purpose 8 Channel Relay Board.

DESCRIPTION

8 Channel Relay Board is a simple and convenient way to interface 8 relays for switching application in your project. Input voltage level support TTL as well as CMOS. Easy interface with Microcontrollers based projects and analog circuits.

SPECIFICATIONS:

  • Input supply 12 VDC @ 336 mA
  • Output eight SPDT relay
  • Relay specification 5 A @ 230 VAC
  • Trigger level 2 ~ 15 VDC
  • Header connector for connecting power and trigger voltage
  • LED on each channel indicates relay status
  • Screw terminal connector for easy relay output and aux power connection
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 152 mm x 60 mm

SCHEMATIC

8_Channel_Relay_Schematic

PARTS LIST

8_Channel_Relay_Bom

PCB

ELECTRONIC TOGGLE SWITCH

The Project works as electronic toggle switch.

DESCRIPTION

The circuit is based on CMOS CD4013 Flip Flop IC, The circuit has two stable states, ON and OFF. Once it is ON, it remains ON till you press the switch again. A short button press of a tactile switch SW1 latches the circuit ON and another toggles it back OFF.

Relay switch contacts can handle high AC Voltage as well as High DC current, this makes the project suitable for application like ON/OFF Fan, Light, TV, Pump, DC Motor, any electronic project required electronic toggle operations and few other devices work on AC voltage up to 250V AC or DC current up to 5Amps.

Applications: TV, Audio Equipments, Radio, Fan, Pump, DC Motor, Electronic Projects ON/OFF

SPECIFICATIONS

  • Supply: 12V DC
  • Current: 60mA
  • D1: Power Indicator
  • D3: Toggle State ON or OFF indicators
  • CN1: Supply Input
  • SW1: Toggle Operation

SCHEMATIC

003_Schematic

PARTS

003_Bom_th

PCB

ONE CHANNEL RELAY DRIVER

This project is an one Channel Relay Driver suitable for a variety of projects.

DESCRIPTION

Single Channel Relay project  is a simple and convenient way to interface a relay for switching application in your project.

SPECIFICATIONS:

  • Input – 12 VDC @ 42 mA
  • Output – SPDT relay
  • Relay specification – 5 A @ 230 VAC
  • Trigger level – 2 ~ 15 VDC
  • Header pins for connecting power and trigger voltage
  • LED indicates relay status
  • Power Battery Terminal (PBT) for easy relay output connection
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 27 mm x 69 mm

SCHEMATIC

ONCE_CHANNEL_RELAY_DRIVER_SCHEMATIC

PARTS LIST

ONCE_CHANNEL_RELAY_DRIVER_BOM

PCB

DC MOTOR DIRECTION CONTROLLER WITH TACT SWITCHES

DC Motor Direction Control project offers direction control using digital logic gates and a DPDT relay.

FEATURES

  • Supply input 12 VDC @ 75 mA
  • Power LED
  • DC Motor Direction LED Yellow/Green
  • Relay Output: up to 7 A
  • Onboard tactile switch for direction control
  • Relay based drive design with diode protection
  • LED indicator for direction indication
  • Power-On LED indicator
  • Terminal pins and screw terminal connector for easy input / output connection
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 41 mm x 81 mm

SCHEMATIC

DC_Motor_Direction_Controller_SCH

PARTS LIST

DC_Motor_Direction_Controller_BOM

PCB

DC SERVO MOTOR DRIVER

DC Servo Motor Driver kit, designed using MC33030 IC, is the fastest and low cost way of getting your DC Servo Motor up and running.

  • Input – 12 VDC
  • Output – can drive upto 1 A Load
  • Overcurrent shutdown, overvoltage shutdown
  • Programmable reference input
  • Power-On LED indicator
  • Relimate connector for interfacing the kit
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 45 mm x 54 mm

SCHEMATIC

schematic (1)

PARTS

parts

 

PCB

UNIPOLAR 4-PHASE STEPPER MOTOR CONTROLLER

This project is a 4-phase unipolar stepper motor controller.

DESCRIPTION

Unipolar 4-Phase Stepper Motor Controller Board will help you control a Stepper Motor or 4 individual Solenoids. This circuit consisting of transistors that serve as current amplifier and also diode to prevent damaging back EMF, circuit uses Darlington transistors to provide high current capacity to unipolar stepper motor. Just provide sequence of pulse using Micro-Controller or descript circuit to roll out the unipolar motor. On board High Watt resistor to control the current, value of the resistor can be set as per your load current requirement.

SPECIFICATIONS

  • Box Header (IDC) connector provides for easy interfacing option
  • Separate LED indicator for individual Phase
  • Screw terminal connector for easy connection of output load and power supply input
  • Power-On LED indicator
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 86 mm x 49 mm

SCHEMATIC

SCHEMATIC

 

PARTS LIST

BOM

PHOTO

C055

PCB

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