| 1) A simple Remote control Tester |
| Here is a handy gadget for testing of infrared (IR) based remote control transmitters used for TVs and VCRs etc. The IR signals from a remote control transmitter are sensed by the IR sensor module in the tester and its output at pin 2 goes low. This in turn switches on transistor T1 and causes LED1 to blink. At the same time, the buzzer beeps at the same rate as the incoming signals from the remote control transmitter. The pressing of different buttons on the remote control will result in different pulse rates which would change the rate at which the LED blinks or the buzzer beeps.
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| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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| 2) Fun / Quiz Circuits For Beginners |
| Here you can learn simple method for making your own fun/quiz circuit board. This is very simple electronic project for beginners. This project can be used for a quiz with up to 4 contestants (or teams). Each contestant has a trigger push-switch and LED. When a trigger switch is pressed it lights the corresponding LED, sounds the bleeper and prevents the other trigger switches from working - therefore showing which contestant was the first to press their switch.
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| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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| 3) Audio amplifier output relay delay |
| For controlling the speaker output relay, this circuit is widely used in the entire electronics industry. The purpose of this circuit is to control the relay which turns on the speaker output relay in the audio amplifier. The idea of the circuit is wait around 5 seconds ofter the power up until the speakers are switched to the amplifier output to avoid annoying "thump" sound from the speakers. Another feature of this circuit is that is disconnects the speaker immediately when the power in the amplifier is cut off, so avoiding sometimes nasty sounds when you turn the equipments off.
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| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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| 4) Computer Microphone For Beginners |
| Are you wholeheartedly interested in making your own computer microphone? If yes, you are at right place. The sound card for a PC generally has a microphone input, speaker output and sometimes line inputs and outputs. The mic input is designed for dynamic microphones only in impedance range of 200 to 600 ohms. Lazar has adapted the sound card to use a common electret microphone using this circuit. He has made a composite amplifier using two transistors.
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| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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| 5) Low Noise Balanced Microphone Preamp For Engineers |
| Here is the simple circuit diagram of noise balanced microphone preamp which produces very low noise as well as high hum rejection and variable gain with a single rotary pot, similar to that used in many professional grade mixing desks. It is similar to that used in many professional grade mixing desks and can form the basis of a no compromise recording mixer for live work. The design consists of differential compound pairs of transistors with a common mode (floating) gain control connecting the emitters of the pair. The compound pairs of 2N4403 and BC549s are far more linear than any single transistor.
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| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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| 6) Zener Diode Tester For Beginners |
| Here is a handy zener diode tester which tests zener diodes with breakdown voltages extending up to 120 volts. The main advantage of this circuit is that it works with a voltage as low as 6V DC and consumes less than 8 mA current. The circuit can be fitted in a 9V battery box. Two-third of the box may be used for four 1.5V batteries and the remaining one-third is sufficient for accommodating this circuit. In this circuit a commonly available transformer with 230V AC primary to 9-0-9V, 500mA secondary is used in reverse to achieve higher AC voltage across 230V AC terminals.
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| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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| 7) Signal Tracer |
| Here is the simple circuit diagram of signal tracer. Reliability and durability are some of the outstanding characteristics of this project. From the initial step of preparation to the final working i.e. the whole manufacturing process is given with detail description. Here is the process: the main part of this circuit is the LM386 amplifier chip. It also uses a transistor input to buffer the input signal and provide extra gain for the LM386. The little unit has helped me out on numerous occasions when trouble shooting any amplifier circuit like a stereo receiver, TV / VCR audio section, radios, CD players and car stereos.
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| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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| 8) Simple Car Battery Charger |
| You all are wholeheartily welcomed to this website bringing simple circuit diagram of car battery charger. For charging the battery just connect the positive and negative terminals of the circuit to the corresponding terminals of the battery. When the battery is not charged, the ammeter reading shows 1-3 amps. When the battery is fully charged the ammeter reads Zero or nearly zero, after which the battery should be removed from the charger. The circuit is a full wave rectifier using 2 diodes for rectification.
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| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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| 9) Dummy Alarm For Beginners |
| This project makes a superbright LED flash briefly once every 5 seconds to imitate the indicator light of a real alarm. The circuit is designed to use very little current to prolong battery life so that it can be left on permanently. This Dummy Alarm project makes an LED flash briefly once every 5 seconds to imitate the indicator light of a real alarm. The circuit is designed to use very little current to prolong battery life so that it can be left on permanently. An on/off switch is not included, but could be added if you wish.
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| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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| 10) Reverse Bias Oscillator For Beginners |
| Welcome to this website which brings the complete and detail description of reverse bias oscillator. There are a number of NPN transistors that will oscillate in the audio range when reverse biased. Minimum supply voltage is 7V for low power transistors such as BC109, BC238 and 2N2222A, it becomes 12V for medium power transistors such as BD139 and is 16V for power transistors as BUX22 and 2N6543. Current drain is 4mA at 9V and frequency of oscillation is 550Hz. The base is normally left open. |
| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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| 11) Color Sensor For Engineering Students |
| Color sensor is an interesting project for hobbyists. The cir cuit can sense eight colors, i.e. blue, green and red (primary colors); magenta, yellow and cyan (secondary colors); and black and white. The circuit is based on the fundamentals of optics and digital electronics. The object whose color is required to be detected should be placed in front of the system. The light rays reflected from the object will fall on the three convex lenses which are fixed in front of the three LDRs. The convex lenses are used to converge light rays. This helps to increase the sensitivity of LDRs. Blue, green and red glass plates (filters) are fixed in front of LDR1, LDR2 and LDR3 respectively.
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| Category: Sensors -> Applications |
| Posting Date: July 08, 2008 |
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| 12) LED-based Emergency Light |
| Are you keenly worried for the power cut? Here is the solution. By following some simple instructions as well as steps, you can make your own LED-based emergency light. The circuit of automatic emergency light presented here has the following features: 1. When the mains supply (230V AC) is available, it charges a 12V battery up to 13.5V and then the battery is disconnected from the charging section. 2. When the battery discharges up to 10.2V, it is disconnected from the load and the charging process is resumed. 3. If the mains voltage is available and there is darkness in the room, load (bulb or tube) is turned on by taking power from the mains; otherwise the battery is connected to the load.
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| Category: Semiconductors -> Applications |
| Posting Date: July 08, 2008 |
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| 13) Soft ON/OFF switch for engineering students |
| Modern electronic equipment incorporate "push-to-on-push-to-off" switches that do not make the clicking noise as with old equipment. An example of this is the power button on a ATX computer cabinet. Here is a circuit that does the same. It can be used to turn on/off any electronic/electrical equipment that operates on any range of voltages. When the "ON/OFF" button is pressed once, the equipment goes on and stays on. It goes off when the button is pressed again. The circuit is straight forward. It uses a JK CMOS FlipFlop to with its JK terminals tied high to achieve the toggling action.
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| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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| 14) Hand Clap Electronic Control |
| Are you familiar with CLAP-ON as well as CLAP-OFF circuits? If not, you are at right place. This circuit is the matchless example of CLAP-ON as well as CLAP-OFF circuits. Here you can see the detail well as complete working of CLAP-ON as well as CLAP-OFF circuits. Circuit operation is as follows. A single hand clap will be picked up by the electric mic which is coupled through C1 into the op amp IC1. The output of IC1 triggers the 555 IC timer IC2 which is configured as a monostable multivibrater. The trigger pulse is stretched by IC2 and outputs a pulse to IC3 a D type flip flop.
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| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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| 15) Full-duplex doorphone with 3 wires connection |
| Here is the simple circuit diagram of full-duplex doorphone with 3 wires connection. When it comes to the most authentic full-duplex doorphone then this circuit is counted on the top rank. This circuit is a two-way (full-duplex) construction planned for use as doorphone. To use, two pieces of the same circuit must be connected together with three wires: MINUS (ground), PLUS (power) and LINE. One of the circuits must be connected to a stabilized power supply, 6-30VDC.
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| Category: Design -> Applications |
| Posting Date: July 08, 2008 |
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