Transformerless power supply circuit

Transformerless power supply Description. Here is a low cost and simple circuit that can be used to power up small electronics devices. The power is directly tapped from the mains via resistor R1.D1 rectifies the voltage and C1 and C2 are used to filter the output.The zener diode D2 keeps the voltage at steady 5V. Transformerless Power Supply Circuit Diagram with Parts List.   Notes. This circuit can deliver only up to 2omA ,there fore not suitable for serious circuits. You can use this power supply for small LED circuits etc . Remember you are playing with mains.Always be careful…

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Remote control tester circuit

Remote control tester Description. This is a simple remote controller tester circuit  based on infrared sensor IC TSOP 1738. When the IR waves fall on the sensor it output changes to low state.This makes the transistor Q1 ON and LED will blink according to the code contained in the signal. So for press of each button the LED blinks in different ways. This is a good indication of the working of remote.The diode D1drops 0.7 V to give the IC ~ 5V supply from the available 6V . R2 is a current limiting resistance. Get a better understanding on the…

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Transistor Amplifier Circuit-12 Watts

12 Watts Transistor Amplifier Circuit Description. The circuit shown below is not at all expensive as the amplifier contains only an op-amp and four transistors (easily available from your electronics junk box).Here the op-amp used is uA 741 which produces the required gain.The four transistors are wired as complementary Darlington’s which produces the drive for the speaker. The voltage drop across the resistors R2 and R3, are used as the input of the Darlington pairs . As the input current to the op-amp depends on the level of the signal op amp is amplifying the voltage drop across the resistors…

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USB LED Lamp circuit.

USB Lamp Circuit Description. Here is a simple USB powered lamp that can be used to light your desktop during power failures. The circuit operates from the 5 Volt available from the USB port.The 5V from the USB port is passed through current limiting resistor R2 and transistor Q1. The base of transistor Q1 is grounded via R1 which provides a constant bias voltage for Q1 together with D2.The diode D1 prevents the reverse flow of current from battery.C1 is used as a noise filter.Two white LED’s are used here for the lamp, you can also use a 2 V…

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6 Volt regulator circuit using 7806

6 Volt Regulator using IC 7806 Description. Here is the elementary 6V 1A power supply circuit using 7806 IC. The 7806 three-terminal positive voltage regulator is available in the TO-220/D-PAK package making them useful in a wide range of applications. 7806  employs internal current limiting, thermal shut down and safe operating area protection, making it essentially indestructible. If proper heat sinking is provided, it can deliver over 1 ampere output current. Voltage Regulator Circuit Diagram with Parts List . Pin out of 7806 Notes . If 2A bridge is not available make one with four 1N 4007 diodes. Fit a…

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Remote controlled switch circuit

Remote controlled switch for Appliance Description. Here is a versatile remote controlled  switch that can ON or OFF any appliance connected to it using a TV remote. IR remote sensor IC TSOP 1738 is used for receiving the signal. Normally when no signal is falling on IC3 the output of it will be high. This makes Q1 OFF.When a signal of 38 KHz from the TV remote falls on the IC3 its output goes low.This makes Q1 conduct and a negative pulse is obtained at pin 2 of IC 1 NE 555. Due to this IC1 wired as a monostable…

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Burglar alarm circuit

Simple Burglar Alarm Circuit Description Here is a simple but effective burglar alarm circuit that can be fixed on windows to detect break through. The circuit uses a fine wire element fixed as a network through the window  glass  for sensing the break through . Normally the base of Q1 is held to ground potential by the wire element.So Q1 will be off and SCR H1 will not be conducting,and horn will be off.When the  wire element is broken the base of Q1 will be raised to positive potential, Q1 will be on and so SCR H1 (TYN 612) will…

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Tweeter Crossover circuit

Tweeter Crossover Circuit Description A single coil speaker is not good in handling high and low frequency at the same time. If we could filter out the low frequency and play it through a tweeter ,it will produce more sound quality than using a single speaker.This is what is realized here.Here the high frequencies are filtered out using a low pass filter made of C1,C2 and R1 and send to the tweeter.The low frequency is only fed to the woofer. Crossover Circuit Diagram with Parts List Notes The tweeter can be a 2 to 3 inch, 4 to 8 Ohm…

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Function Generator Circuit

Function Generator Circuit Description. The ICL8038 is a function generator chip, capable of generating triangular, square , sine, pulse and sawtooth waveforms . From these sine, square & triangular wave forms can be made simultaneously.There is an option to control the parameters like frequency,duty cycle and distortion of these functions.This is the best function generator circuit for a beginner to start with and is of course a must on the work bench of an electronics hobbyist.The circuit here is designed to produce waveforms from 20Hz to 20 kHz.The ICL 8038 has to be operated from a dual power supply. Function…

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Lead acid battery charger circuit

Lead Acid Battery Charger Description Here is a lead acid battery charger circuit using IC LM 317.The IC here provides the correct charging voltage for the battery.A battery must be charged with 1/10 its Ah value.This charging circuit is designed based on this fact.The charging current for the battery is controlled by Q1 ,R1,R4 and R5. Potentiometer R5 can be used to set the charging current.As the battery gets charged the the current through R1 increases .This changes the conduction of Q1.Since collector of Q1 is connected to adjust pin of IC LM 317 the voltage at the output of…

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