IR Transmitter and Receiver Circuit for Best Remote Control System

A remote control system for appliances makes our life smarter and easier. The wireless remote control circuit may be based on IR waves or RF waves, IR being cheaper. An IR emitter circuit is based on TSOP at the receiver section. Each TSOP operates at a particular frequency which depends on a number present on it. So each TSOP requires specific remote controller for its operation. There comes the importance of IR universal remote control which can be used to operate all normal hobby circuits.

Here the basic principle of operation is Frequency Shift Keying (FSK). It enables to generate variable frequency so that it can detect different TSOPs.We are using two 555 timers here, both operating in astable mode which then drives the IR led.

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Simple Door Phone Intercom Circuit Schematic (Duplex)

A door phone intercom system provides a two-way conversation that is cost free. It can be very useful in hospitals, hotels and as a free of cost communication to a friend’s house.

Earlier I had already published another two way communication intercom circuit but it had the disadvantage of switching (same speaker is used both as mic and speaker based on the switch positions).

The main component used here in this two way intercom circuit is an 1895 IC. It is a 1 watt audio amplifier. Here we are using two condenser mics and two speakers for communication. Calling tone is generated by using melody generator IC UM66.

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Simple Emergency Light Circuit with Automatic Charger

Some of our readers requested for Emergency circuit with charge controller. Here I'm presenting  such kind of a circuit diagram with automatic charging.

It is very easy to implement on your home and work areas.Our circuit is capable of turns on the light automatically when power failure occurs and turn off if main supply is return.

LEDs are used as emergency light bulbs in this system, The important specialty of this Emergency circuit is an automatic charge controller which recharge the battery if the voltage is below the threshold level and cut off the charging supply to the battery, if the voltage reach at the pre-set level, two LEDs are used to indicates the of presents of main power and activation of charger.

This circuit mainly focus to lead acid battery life, in this circuit design we limit the maximum charging voltage is 13.8V as per lead acid battery manufacturers.

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How to Make a Simple Boost Converter with 555 Timer?

We may come across many circumstances where we need 12V from a 5V (as from USB ports which only provide 5V), but it may not be sufficient to drive all the circuits. To face such situations we are introducing a dc to dc boost converter circuit which can generate 12 volt from 5 volt. Today boost converter applications are used in different devices like dc dc power supply, dc-dc converter module, isolated dc dc converter etc. The main component used for this circuit is a 555 timer IC operating in astable mode. It generates a square pulse which is then given to a simple transistor inverter to get inverted outputs. These two outputs will drive a voltage pump which increases the voltage level by series addition. However this 555 timer boost converter has a disadvantage of low output current so it can’t drive high current devices. To get more current you have to use a step up converter circuit that we will introduce later.

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Real Time Clock Circuit using Mircocontroller

Here I am going to teach you a simple circuit of 24 hour digital clock display that can also be used in 12 hour format by simply loading the corresponding clock program. You can download the hex files for both 12 hour format and 24 hour time system from the link given in this article. Coming to the technical part, main component of the circuit is a PIC16f84A microchip; it generates the one second clock to run the device and also controls the seven segment display. Three push buttons are also provided to set the time; one for reset by which you can reset the complete circuit as it is connected to the reset pin of PIC microcontroller. Other two push buttons are for setting hour and minute. By Pressing these button continuously you can increment hour and minutes.

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Automatic Rain Sensing Wiper System using 555 Timer

Have you seen Audi, Lexus or Ford rain sensing wipers and wondered how they work in these vehicles? They are handled by sensors at the center of the windscreen which detects rain water and turns on the wiper motor. Here is the working of rain sensitive wipers with circuit schematic. The main component of this circuit is a 555 timer IC that works in monostable mode. Two metal sheets fixed at a small distance apart are used as rain detector sensors. From the working of a monostable 555 timer, a negative voltage on the trigger pin will cause a high output. So when it rains, trigger pin gets a negative voltage. Output of one shot 555 (monostable) is connected to a relay through a transistor. The transistor acts as a switch for the relay to turn ON the wiper motor during rain.

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Multi Channel Remote Control System

Here is a hobby circuit of a multi channel remote control system, by which you can control 8 different appliances. The main sections of this multi channel remote control circuit are the RF receiver and transmitter. By using this circuit we can control 8 devices, each of them independently by pressing the push buttons. When the button is pushed, corresponding relay is turned ON and is turned OFF on the next push. Here the relay load current is dependent on the relay used. A serial encoder IC HT12E and a serial decoder IC HT12D are used, where the encoder IC encodes the parallel data to serial and decoder IC decodes the serial data to parallel during the wireless transmission. You must need a regulated power supply of 5 volt for this circuit because ICs 7476 and 74138 requires 5v for its operation. The main advantage of this system is that it does not require a ‘line of sight’ as compared to IR remote control systems; also it gives longer distance control.

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555 Touch Sensor

How to make a touch sensor? Here is a simple DIY touch sensor circuit diagram using 555 timer monostable mode. Touch switch is only a conducting metal sheet that acts as touch sensor. The 555 touch switch is not a touch capacitive sensor; it is only a metal touch sensor button. Using this you can turn on and off devices by single touch. Here we are using a JK flip flop IC 7476 that is connected as T-flip flop. The output of T-flip flop is connected to the base of transistor to turn ON the relay so as to control high current electrical devices such as fan, motor, lamps etc.

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How to Build your Own USB PIC Programmer?

This DIY PIC programmer is a continuation of our PIC programming basics tutorial. By using this USB PIC programmer, you can program microchip PIC series of 10F, 12F, 16F, 18F, 24F, 30F. This is also an EEPROM programmer as it supports 12Cxx EEPROM. The main component of this PIC microcontroller programming circuit is a PIC182550 microcontroller which controls the overall circuit. Serial port PIC programmers are the widely used PIC chip programmer Kit, but since laptops have no RS232 ports they require an USB to RS232 converter.

Recommended for you:

• PIC microcontroller Beginner's guide: Basic connection circuit 
• How to burn or program PIC Microcontroller? 

Now one of the main advantages of this circuit is that it does not require any external power supply, instead it uses USB power. It generates programming voltage of 13V through voltage multipliers. Linux PIC programmer software is also available for burning. You can program micro controller like pic16f84a, pic16f877a, pic18f4550, pic16f628a etc. and make your micro controller programming easier.

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12v Battery Charger Circuit with Auto Cut off

This is a simple DIY charge controller schematic posted in response to a request by one of our readers on our facebook page. The main component of this auto battery charger circuit is a 555 timer which compares the voltage in the battery. It turns ON the charger if the battery voltage is below the variable preset voltage (12 volt chosen here) and turns OFF the charger if the voltage reaches 13.8 volt. The battery charging voltage of the charger can be varied by adjusting the variable resistor and maximum charging is limited by a 13.8V zener diode on the fifth terminal of 555 IC.

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Simple Solar Table Lamp Circuit for your Home

Solar energy has now become a popular alternative for the production of electricity. Here is a green energy project for school students on how to make solar lamps for your home. The main component of this simple solar lamp circuit is a small solar panel and a battery using rechargeable cells. This battery can light the white LED’s and provide sufficient amount of light in your room for a longer period.

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How to Build a Digital Voltmeter of your Own?

How to build a voltmeter for DC voltage measurements without using multimeter testing? This is a simple digital voltmeter circuit that can measure voltages from 0V to 9V.The main part of this circuit is a dot bar display driver IC LM3914. Input voltage applied to this IC generates an output which is converted into a binary value by the priority encoder IC 74147. It is then displayed on the seven segment display by the help of a common anode seven segment display driver IC 7447.However the voltmeter accuracy of this digital voltmeter schematic is limited to a sensitivity of 1V.

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Simple Over Voltage Protection Circuit: High Voltage Cut Off

Voltage fluctuation is a serious issue in every home. Due to some reasons our supply voltage may rise above 110V or 230V. Flow of this high electricity may lead to the damage of our home electrical devices. Have you thought how electrical protection is possible via a simple over voltage protection circuit? Here CG comes with an interesting over voltage protection device to protect your electrical appliances from getting damaged. Zener diode voltage regulator is the main part of this high voltage cut off circuit. You can implement this over voltage protection relay circuit in your home as a high voltage regulator.

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How to make a circuit of Automatic Street Light control system?

Automatic street light system is very common nowadays as it provides intelligent street lighting mechanism. It provides light automatically during night without any human interference. These energy saving street lights make use of incandescent lamps instead of LEDs.

So here I will teach you how to make an electronic circuit for street light automation. The heart of this circuit is a LDR (Light Depended Resistor) which is connected as a potential divider with a 56K resistor. The drop across LDR is used for switching the transistor. Solar led street lighting systems are the advanced versions of this ordinary automatic street light controller.

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LED 12v Emergency Light Circuit Diagram

Here is a simple LED emergency light circuit that you can implement for home lighting during power failures. We know that LED bulbs consume very less power and hence they have a much longer life. This LED lighting circuit design is intended to light automatically during main power failures. So here we are going to help you with the building of cheap emergency lights. The main part of this led light schematic is a relay, which automatically connects DC voltage to the battery when main power is present and connect LEDs to the battery in the absence of main power supply.

Upon request from our readers, we have integrated this with an automatic battery charger circuit. See our updated  emergency with automatic charge controller.

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Remote Controlled DC Motor for Toy Car Circuit Diagram

This is a simple hobby circuit of a remote controlled toy car. The main component used here is the IR sensor circuit consisting of TSOP. Using a TSOP IR receiver we can start and stop the DC motor vehicle. However this circuit has a small disadvantage that it can’t control the speed of DC car motor, rather it ON and OFF the small dc motors. Thus it is suitable for electronics beginners only.

Once it is ON, the motor runs with a constant speed. No speed control circuits are discussed here. The advanced version of this circuit with PWM speed controller will be posted soon. You must need a regulated power supply of 5 volt to do this one because TSOP requires 5v for its operation. Below is the circuit diagram and working of remote controlled dc motor for car using T sop infrared detector circuit.

Note: TSOP voltage should not exceed 5V.

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Water level sensor circuit: projects for school students

I have posted wide varieties of small electronic projects on water level sensor  in Circuits Gallery. This is another project for school students to detect the water level inside a water tank or any other water reservoir. We can call this as a ‘liquid level sensor’, because this circuit is able to sense the presence and absence of liquid in a tank.

This school electronic project is built around BC548 transistors and a 7432 OR gate IC. This water alarm will produce a beep sound when the water goes below a specified level (h1) or when the water overflows. This is one of the home science experiments that can be implemented as science projects for high school students.

You may also like to have a look at our other science experiments like automatic water tank level controller and numeric water level indicator. I have also published an article to detect overflow of water using alarm.

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Home security alarm system circuit diagram

Have you ever thought about implementing your own home security alarm systems? It's one of the simplest and interesting circuits for electronic beginners. Our new home security equipment uses a LDR (Light Depended Resistor) to detect security problems. Theft attempt and other security threats can be controlled by using this simple circuit to improve your security systems. This is also best suited for school students for their high school science projects.

To implement this alarm system for home, you have to provide an optical path (with LASER beams) around your home. The LASER path is made possible with one LASER torch and 3 mirror arrangements which encloses the whole area. Please refer the project arrangement section below to make this optical (light) path. We have explained about home security system in detail with animation/ simulation.

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Simple fire alarm- thermistor circuit diagram

Here i-St@r comes with a simple and automatic fire alarm and detection system. This fire detection alarm circuit is based on thermistor. What is a thermistor? A thermistor is nothing but a variable resistor whose resistance increases as temperature decreases. Fire detection is simply possible via this low-cost alarm circuit.A simple potential divider arrangement using thermistor is capable of sensing the temperature (presence of fire) and alerting us with a warning signal. This is suitable for your home security systems. Also school students can do this fire detector circuit as their high school science fair projects. Here I will explain in detail about fire alarm circuit wiring with animation/ simulation of fire alarm.

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Low water level indicator alarm circuit for Water tank

Most of the time we wish to have a water low level alarm (liquid level alarm) circuit to know if the amount of water inside the tank has decreased in order to switch ON the water pump set. Don’t worry about that, we can implement a simple water low level indicator sensor alarm circuit for your home or office with the help of liquid level probes. Our water level sensor alarm detects the fluid level using a transistor switching circuit. We have already discussed about different types of fluid level alarms and water tank level indicators, they are mainly to detect overflow from the water tank. But this one indicates that the tank is near to be emptied.

(This circuit is posted as per the request from one of our reader MR. Ramz)

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