Rongge

This is a Password based Door locking system with GSM. The project mainly consisting of PIC microcontroller (16F877), 16x2 LCD Display, GSM Modem, Keypad and misc.(Relay, Crystal oscillator, power supply which is not shown in circuit diagram) The program is compiled using PICC Compiler and simulated on Proteus 8. All Header and simulation files are given at the bottom of this post. The default password is set as 123. This project can be implemented anywhere where, higher security is required. If the user enters correct password, that is “123”, the relay gets active and opens the door. If an un-authorised person trying to access the system and enters the password incorrectly three times, the system gets locked and alert the owner by sms using Gsm modem. Once the system gets locked a count down timer will appear on lcd and you have to wait that predetermined time period. Read More.....

Controlling temperature has been a prime objective in various applications including refrigerators, air conditioners, air coolers, heaters, industrial temperature conditioning and so on. Temperature controllers vary in their complexities and algorithms. Some of these use simple control techniques like simple on-off control while others use complex Proportional Integral Derivative (PID) or fuzzy logic algorithms. In this project Shawon Shahryiar discusses about a simple control algorithm and utilize it intelligently unlike analogue controllers. Here are the features of this controller: Audio-visual setup for setting temperature limits. Fault detection and evasive action. Temperature monitoring and display. Audio-visual warning. System status. Settable time frame. Data retention with internal EEPROM memory. [ ]

Because I’m old school, I wanted to build a Garage Door Closing circuit without relying on integrated configurations (555 timer etc) to keep it simplistic. The circuit closes the garage door after two minutes with C3 and four minutes with the addition of C2. The timer relay is surprisingly accurate (+/- five seconds). Another feature is to ensure that the garage door actually did close, such as if it’s stopped mid-operation by the user. S3 (magnetic N.C.) is located at the garage door and activates the circuit when the garage door opens. RL1 is the reset timer. It’s maintained in the “on” position for two minutes by C3 while the trigger capacitor, C4, is charged. RL2 is the conduit, directing C4 to either RL3 or R1 to ground when off. Purpose of R1 is to prevent arching across contacts and a fast discharge. RL3’s contacts are connected to the Garage Door’s Momentary Switch and is sustained “on”  for a half second by C5. When C3 discharges to the cutoff voltage of RL1, it turns off ...

This Circuit Audio Amplifer with IC TBA 611 require voltage  4,5 to 15 Volt. I recomended to this circuit supply with 12 volt . Output audio is mono with power 1 Watt. See this circuit and datasheet IC TBA611 below: Datasheet IC TBA 611 Vcc                = 4,5-15 V Pout               = 1 W RL                 = 8 Ohm Ft                   = 50-15 Khz Icco               = 10 mA Package         = TABS4-14 Manufactered = RFT

Most engineers will recognise the problem: Your circuit needs a stable 1 or 2 MHz clock generator (in the author’s case it was for a Pong game using an old AY3-8500). A suitable crystal is not to hand so you cobble together an RC oscillator (there are plenty of circuits for such a design). Now it turns out that you don’t have exactly the right capacitor so a preset pot is add e d to allow some adjustment . Before you know it the clock circuit is taking up more space on the board than you had hoped.  Providing the application does not demand a precise clock source a tiny 8-pin microcontroller may offer a better solution to the problem. It needs no additional external components and an old ATtiny15 can be found quite cheaply. Another advantage of the solution is that clock frequency adjustment does not involve changing external components and is not subject to component tolerances.  The microcontroller’s internal RC oscillator is already accurately calibrated to 1.6 MHz. With i...

Description. A very simple battery charger circuit having reverse polarity indication is shown here.The circuit is based on IC L200 . L200 is a five pin variable voltage voltage regulator IC.The charging circuit can be fed by the DC voltage from a bridge rectifier or center tapped rectifier.Here the IC L200 keeps the charging voltage constant.The charging current is controlled by the parallel combination of the resistors R2 & R3.The POT P1 can be used to adjust the charging current.This circuit is designed to charge a 12 V lead acid battery.The transistor t1,diode D3 and LED are used to make a battery reverse indicator.In case the battery is connected in reverse polarity ,the reverse polarity indicator red LED D5 glows.When the charging process is going on the battery charging indicator green LED D4 glows. Circuit diagram with Parts list.   Notes.  The circuit can be assembled on a good quality PCB or common board. The values of R2 & R3 can be obtained from the equatio...

The FM transmitter circuit is using NPN transistor 2N2222. The L1 and C1 producess necessary oscillations Q1.The collector capacity C4, R3 and R4 resistor performs the function of the output mix theaudio to stereo player or i-emitter resistor R2 Pod.The provides sufficient stability for circuit.It also limits the collector current increse the battery. With this circuit compact FM adapter connected to the audio output of your cassette player or i pod words, you can listen to your favorite music on the car track is stereo.This doesnot handy if your car stereo has an auxiliary circuit outlet is not to buy a short-range FM transimitter.

The PR4403 is an enhanced cousin of the PR4402 40 mA LED driver. It has an extra input called LS which can be taken low to  turn the LED on. This makes it very easy  to build an automatic LED lamp using a  rechargeable battery and a solar module. The LS input is connected directly to the solar cell, which allows the module to be  used as a light sensor at the same time as  it charges the battery via a diode. When  darkness falls so does the voltage across  the solar module: when it is below a thresh-old value the PR4403 switches on. During  the day the battery is charged and, with  the LED off, the driver only draws 100 µA. Circuit Diagram : Solar Lamp using the PR4403 Circuit Diagram At night the energy stored in the battery is released into the LED. In contrast to similar designs, here we can make do with a single  1.2 V cell. The PR4403 is available in an SO-8 pack-age with a lead pitch of 1.27 mm. The  other components are a 1N...