Delay Switch with OP Amp [Schematics + DSN]

Hey, Guys I have received a mail from one of my friend at 22 march about a Circuit Diagram. I mean, He has made a working Schematic of Delay Switch using OP Amp. I Know, There are lots of web Blog and Ton's of Schematic available for this particular Design. But This is the simplest on I have ever seen.

SIM Reader : Schematics, Software, and Tools

SIM Card Reader Overview

This project details how to build a Smart/SIM card reader/writer for experimentation and investigation of SIM & Smart cards.Once the reader design is built, the open source software can be used to read from and write to the card. Together they can be used to backup/restore stored SIM.

RFID-Based Security System (Circuit Diagram)

A radio-frequency identification (RFID) based access-control system allows only authorised persons to enter a particular area of an establishment. The authorised persons are provided with unique tags, using which they can access that area.

The system is based on micro controller AT89C52 and comprises an RFID module, an LCD module for displaying the status and a relay for opening the door. Fig.1 shows a user trying to open the door by placing an RFID tag near the RFID reader.

Dual Adjustable Power Supply Circuit

This is the circuit diagram of a dual adjustable power supply using IC’s LM 317 & LM 337.LM 317 is able to deliver a maximum of 1.5 A at a range of 1.2 V to +30V .LM 337 is the negative complement of LM317.They also have a built in short circuit protection.

Here the circuit is wired to produce a dual adjustable output of ( +15 , 0 , -15 ).The capacitors C1 to C8 provides filtering and ripple rejection.Resistors R1 & R2 controls output of LM 317.Resistors R3 & R4 controls the output of LM 337 .R1 and R4 can be turned to vary the positive and negative voltages.This circuit is a must on an electronic hobbyists workbench.

Circuit Diagram :-

15W Audio Amplifier Circuit (Class B)

The circuit shown here is of a simple Class-B audio amplifier based on op-amp TL082, transistors TIP41 and TIP42. LM833 is a dual op-amp with high slew rate and low distortion particularly designed for audio applications. This audio amplifier circuit can deliver 15 watt audio output into an 8 ohm speaker at +12/-12V DC dual supply.

Both op-amps in the IC are used here. IC1a is wired as a buffer and capacitor C3 does the job of input DC decoupling. Ic1b is wired in the inverting mode and it provides negative feedback. Complementary power transistors TIP41 and TIP42 are wired in the Class B push pull scheme and they drives the loud speaker. Diode D1 provides 0.7V bias voltage for the push pull pair and capacitor C2 protects the 0.7V bias voltage across D1 from heavy voltage swings at the IC1b’s output.

 Circuit Diagram of 15watt Class B Audio Amp :-

Digital voltmeter using ICL7107

Description.

The circuit given here is of a very useful and accurate digital voltmeter with LED display using the ICL7107 from Intersil. The ICL7107 is a high performance, low power, 3.5 digit analog to digital converter. The IC includes internal circuitry for seven segment decoders, display drivers, reference voltage source and a clock. The power dissipation is less than 10mW and the display stability is very high.

Funcation Genrator Circuitusing IC 8038

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.

Circuit Diagram & Part list

ELECTRONIC WATCHDOG

Here’s an electronic watchdog for your house that sounds to inform you that somebody is at the gate.  :D :))))

Circuit Diagram, Arrangement & Component Data (Rx & Tx)

 The circuit comprises a transmitter unit and a receiver unit, which are mounted face to face on the opposite pillars of the gate such that the IR beam gets interrupted when someone is standing at the gate or passing through it.

Low pass filter for subwoofer

Many low pass filter circuits for subwoofer are given here and this is just another one. The circuit given here is based on the opamp TL062 from ST Micro electronics. TL062 is a dual high input impedance J-FET opamp which has very low power consumption and high slew rate. The opamp has excellent audio characteristics and is very suitable for this circuit.

Out of the two opamps inside TLC062, first one is wired as the mixer cum pre amplifier stage. The left and right channel are connected to the inverting input of IC1a for mixing. The gain of first stage can be adjusted using POT R3.The output of the first stage is connected to the input of second stage through the filter network comprising of components R5,R6,R7,R8,C4 and C5. The second opamp (IC1b) serves as a buffer and the filtered output is available at the pin 7 of the TLC062.

LDR Controlled Light Switch

      This is a light switch or light activated relay circuit.The relay on when LDR uncoverd and relay off when LDR covered.Adjust VR1 for light sensitive.LED will turn on at the same time with relay.

Above Figure, Show the Circuit Diagram of Light Switch. This is Project about, When Light will Fall on LDR, It will Behave Like a Switch , Mean Fall on Light on LDR will cause switch OFF and Vice versa.

Simple SD Card Audio Player with an 8-pin IC

    This is a simple SD audio player biult with only an 8-pin microcontroller. The ATtinyX5 series (25/45/85) 8-pin AVR microcontroller has two fast PWM outputs in 250kHz carrier frequency. This enables to output a wide frequency range audio signal. I built an audio player with the 8-pin AVR and an SD memory card (SDC). The SDC can be controlled with only six lines, two for power supply and four for control signals. It can also be easily attached to 8-pin microcontrollers. The main application of the tiny X5 series AVR seems SMPS and related according to its integrated peripherals.

    Anyway this audio player is very simple and a few wires to be solderd so that it is suitable for brief soldering work before breakfast.

Hardware

   Right image shows the world's smallest audio player (as MicroSD player, perhaps...). There are three schematics for the player in different configurations. The recording media to be used is a MicroSD. Of course the standard SDC and MiniSD can also be used by proper socket conversions.

2 km FM transmitter

Description.

     With a matching antenna, the FM transmitter circuit shown here can transmit signals up to a range of 2 kilo meters. The transistor Q1 and Q2 forms a classic high sensitive preamplifier stage. The audio signal to be transmitted is coupled to the base of Q1 through capacitor C2. R1, R3, R4, R6, R5 and R9 are the biasing resistors for the preamplifier stage comprising of Q1 and Q2. Transistor Q3 performs the collective job of oscillator, mixer and final power amplifier.C9 and L1 forms the tank circuit which is essential for creating oscillations. Inductor L2 couples the FM signal to the antenna.

6 Zone Alarm with Display

Description :

     This alarm system has 6 independent zones, 1 timed entry/exit zone, a 7 segment LED display and a test or walkthrough facility. Suitable for a small office or home environment, it can also be adapted to use a combination lock or keypad to set and reset the alarm.

Please Note:    All orange +V terminals connect to the point marked +5V at the side of the set switch, S1. IC's 

                                 1,U2,U3,U4,U5 and U7 are drawn without power connections for clarity. The power connections  

                                 need  to go +5V and ground.

5 Zone Alarm System

Description :

 This is a complete alarm system with 5 independent zones suitable for a small office or home environment. It uses just 3 CMOS IC's and features a timed entry / exit zone, 4 immediate zones and a panic button. There are indicators for each zone a "system armed" indicator. The schematic is as follows :

                        Click on the Image to Zoom it.

Gate Alarm

Description :

 A cheap and simple gate alarm made from a single CMOS Integrated Circuit.

Circuit NoteS

      Figure 1 represents a cheap and simple Gate Alarm, that is intended to run off a small universal AC-DC power supply.

USB Powered Mobile Phone Battery Charger

Now you can charge your Mobile Phone from the USB outlet of PC / Laptop

          This simple circuit can give regulated 4.7 volts for charging a mobile phone. USB outlet can give 5 volts DC at 100mA current which is sufficient for the slow charging of mobile phones. Most of the Mobile Phone batteries are rated 3.6 volts at 1000 to 1300 mAh. These battery packs have 3 NiMh or Lithium cells having 1.2 volt rating. Usually the battery pack requires 4.5 volts at 300-500 mA current for fast charging.

FM Stereo Transmitter [BA1404 (100m)]

This is a small stereo FM transmitter. Output can be tuned from 88to 108Mhz and the transmitter can be battery powered or be used with the low voltage power supply on this page.

Notes :

This circuit is based on the Rhom BA1404 datasheet. The maximum voltage should not exceed 3V. The IC can be driven from a 7805 Regulator with a couple of 1N4001 diodes to reduce the supply voltage to about 2.8 Volts. The IC can dissipate 500mW (this is not RF power output but power dissipated by the IC). RF output power is typically 500mW but range depends upon antenna coupling and efficiency, environment and size of antenna. A small telescopic whip has an expected range of at least 100 meters or more.

150W MP3 Car Amplifier with Advance Fucation

        It is a diagramm of an active loudspeaker. The LF353 of, National Semiconductor, is going to split audio signal into three bands. SANYO'S LA47536 is going to amplify these signals. In stereo mode, we shall have the action of eight high speakers who are going to create a very important sound pressure.

Block Diagram : 

THEORY ::: RC-coupled Amplifiers

          One way to connect various stages of a multistage amplifier is via capacitors, as indicated in the two-stage amplifier in Fig.1 where two stages of common emitter amplifiers are coupled to each other by the capacitor C₃.

                                                   A typical configuration of an RC-coupled amplifier

Line Follower Robot (Enhanced Version)

 

Overview

        This small line follower robot, was designed to be easily built at home without any special equipment, and using a minimum number of mechanical parts. You wont need more than 2 small motors, 2 free wheels and a piece of pcb (to hold the micro-controller, the motors driver and the line sensor) and sure.. your soldering iron!

    The main trick making this design simple and affordable, is that the robot's chassis is actually the main board of the robot, where some supports for the wheels - also made of small parts of copper boards - are soldered to it. All the motors, and the skids are mounted on the main PCB. For an electronics hobbyist, PCB manufacturing is a skill that will be learnt sooner or later, so this design lets you use your experience in PCB manufacturing to design a high precision chassis for your robot.

1. Overall Design