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Project Summary This circuit is a relay driver that is based on a PIC16F84A microcontroller. The board includes four relays so this lets us to control four distinct electrical devices. The controlled device may be a heater, a lamp, a computer or a motor. To use this board in the industrial area, the supply part is designed more attentively. To minimise the effects of the ac line noises, a 1:1 line filter transformer is used. Project Description The components are listed below. 1 x PIC16F84A Microcontroller 1 × 220V/12V 3.6VA (or 3.2VA) PCB Type Transformer (EI 38/13.6) 1 x Line Filter (2×10mH 1:1 Transformer) 4 × 12V Relay (SPDT Type) 4 x BC141 NPN Transistor 5 × 2 Terminal PCB Terminal Block 4 × 1N4007 Diode 1 × 250V Varistor (20mm Diameter) 1 x PCB Fuse Holder 1 × 400mA Fuse 2 × 100nF/630V Unpolarized Capacitor 1 × 220uF/25V Electrolytic Capacitor 1 × 47uF/16V Electrolytic Capacitor 1 × 10uF/16V Electrolytic Capacitor 2 × 330nF/63V Unpolarized Capacitor 1 × 100nF/63V Unpolarized Capa...

Hi everyone! First of all I would like to thank Avinash Gupta for writing all the valuable tutorials and libraries for AVR Microcontrollers and helping people like me to build projects and learn new things. I am dedicating this post to him!   Introduction: Using remote keys from 1 to 4, you can control 4 appliances. You can easily extend this number to as many you wish. For example, if you press key_1 on your remote, fan will turn ON. If you press the same key again, fan will turn OFF i.e each time you press a key configured for an appliance, the condition will toggle. I have programmed the MCU such that all devices will turn OFF on pressing power button(RED COLOR on top of your remote). You can also choose combinations like turning all fans OFF at a time, etc. With little tweaking, you can change the program yourself! The status of the appliances is shown in an LCD. You can ignore this feature if you dont want LCD. I used LCD for developing the code. I main advantage in this project ...

This cell-phone-controlled audio/ video mute switch is highly useful in automobiles. The circuit automatically disconnects power supply to the audio/video system whenever the mobile handset is lifted off the holder for making or receiving a call. You can use any readily available cell-phone holder with some mi-nor alterations or fabricate it yourself as shown in Fig. 1.  Fig. 1: Proposed cell-phone holder   The circuit is wired around IC LM555 (IC1), the CMOS version of timer NE555, as shown in Fig. 2. IC1 is used as a medium current line driver with either an inverting or non-inverting output. It can sink (or source) current of up to 50 mA only, so take care while handling it. The audio/video system is connected to the circuit via normally opened (N/O) contacts of the relay.   Fig. 2: The circuit of the cell phone-controlled audio/video mute switch   When the cell phone is in its holder, LDR1 does not receive any light from white LED1 and its resistance is high. ...

The article discusses a simple IR remote control circuit which is configured for operating a DC motor in response to the switching made from a standard IR remote handset such as a TV remote or a DVD remote. The connected motor can be moved either ways and also can be made to halt. The circuit may be understood with the following explanations: As can be seen in the given circuit diagram, the sensor is any standard three pin IR sensor module which would typically respond to any TV IR remote handset. When an IR (infra red) beam is focused at the sensor, the pin which is designated as the output becomes logic low. This situation persists as long as the beam remains focused at it. The transistor T1 which is a PNP responds to this logic low signal and conducts switching the attached relay RL1. The contacts instantly connect the instantaneous positive potential at the collector of the transistor to pin#14 of the IC1 which is wired as a flip flop circuit. Assuming the initial ...

A phase-controlled dimmer delays the triac turn-on to a selected point in each successive ac half cycle. Use this circuit only for incandescent lamps, heaters, soldering irons, or universal motors that have brushes. Phase Controlled Dimmer Circuit Diagram

Circuit Description: Transmitter This circuit consists of Transmitter and Receiver section. The circuit can be used to control home appliances within a range of 30 meters. In open area, you can expect a range of 100 meters. The circuit comprises HT12 Encoder and Decode IC's. HT12 Encoder is used in the transmitter (remote) circuit where as HT12E is used in receiver circuit. The Encode IC encodes the 4 bits of data and transmit it serially to to RF Transmitter module. These 433Mhz transmitter and receiver modules operate using ASK Modulation. Receiver: For complete information regarding ASK Modulation, click here The converse operation happens in the receiver section. The serial information is given to the decode section and the ICHT12D decodes the 4 bit data and gives across the data pins. The devices are then connected using the ULN2003 high voltage high current buffer. These are some of the images of my own remote. You can design something like this. I had modified it and soldere...

Remote-Controlled Fan Regulator Circuit Diagram . Using this circuit, you can change the speed of the fan from your couch or bed. Infrared receiver module TSOP1738 is used to receive the infrared signal transmitted by remote control. The circuit is powered by regulated 9V. The AC mains is stepped down by transformer X1 to deliver a secondary output of 12V-0-12V. The transformer output is rectified by full-wave rectifier comprising diodes D1 and D2, filtered by capacitor C9 and regulated by 7809 regulator to provide 9V regulated output. Any button on the remote can be used for controlling the speed of the fan. Pulses from the IR receiver module are applied as a trigger signal to timer NE555 (IC1) via LED1 and resistor R4. IC1 is wired as a monostable multivibrator to delay the clock given to decade counter-cum-driver IC CD4017 (IC2).Out of the ten outputs of decade counter IC2 (Q0 through Q9), only five (Q0 through Q4) are used to control the fan. Q5 output is not used, while Q6 output ...

One way to charge batteries rapidly without abuse is to measure cell temperature and tapper the charge accordingly. The circuit uses a thermocouple for this function. A second thermocouple nulls out the effects of ambient temperature. The temperature difference between the two thermocouples determines the voltage , which appears at the amplifier's positive input. As battery temperature rises, this small negative voltage ( 1 degree Celcius between the thermocouples equals 40uV ) becomes larger. The amplifier, operating at a gain of 4300, gradually reduces the current through the battery to maintain its inputs at balance. The battery charges at a high rate until heating occurs and the circuit then tapers the charge. The values given in the circuit limit the battery-surface temperature rise over ambient to about 5 Degree Celcius. Part List : Resistor R1_____620K R2_____43K R3_____10R R4_____2K R5_____0.6R 5W Capacitor C1_____1uF C2_____0.1uF Diode D1_____1N4148 D2_____1N4001 Transisto...

This PIC Controlled Relay Driver circuit is a relay driver that is based on a PIC16F84A microcontroller. The board includes four relays so this lets us to control four distinct electrical devices. The controlled device may be a heater, a lamp, a computer or a motor. To use this board in the industrial area, the supply part is designed more attentively. To minimize the effects of the ac line noises, a 1:1 line filter transformer is used. The transformer is a 220V to 12V, 50Hz and 3.6VA PCB type transformer. The model seen in the photo is HRDiemen E3814056. Since it is encapsulated, the transformer is isolated from the external effects. A 250V 400mA glass fuse is used to protect the circuit from damage due to excessive current. A high power device which is connected to the same line may form unwanted high amplitude signals while turning on and off. To bypass this signal effects, a variable resistor (varistor) which has a 20mm diameter is paralelly connected to the input.   Another...