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Four-Stage FM Transm itter

This FM transmitter circuit uses four radio frequency stages: a VHF oscillator built around transistor BF494 (T1), a preamplifier built around transistor BF200 (T2), a driver built around transistor 2N2219 (T3) and a power amplifier built around transistor 2N3866 (T4). A condenser microphone is connected at the input of the oscillator.

Antisleep Alarm for Students

This circuit saves both time and electricity for students. It helps to prevent them from dozing off while studying, by sounding a beep at a fixed time interval, say, 30 minutes. If the student is awake during the beep, he can reset the circuit to beep in the next 30 minutes. If the timer is not reset during this time, it means the student is in deep sleep or not in the room, and the circuit switches off the light and fan in the room, thus preventing the wastage of electricity.

Binary to 7 Segment Decoder

This circuit displays the Hexadecimal equivalent of a 4 bit Binary Number. The number is displayed on a 7 Segment LED display. There are many Binary to 7 Segment decoders out there, such as the CD4511, DM74LS47, SN7447 and the DM9368. All of which have attractive features, but none have all of them in one package. Another downside is many only display 0 - 9 with few displaying all Hexadecimal digits (0 - F). With many of these chips obsolete and hard to find, my Binary to 7 Segment Decoder is a versatile substiute.

We are on Third Year!

We are very glad to inform to all the users of this website that we have successfully completed two years serving the electronics students all over the world. We would like to thank to all the users that we have been a part of it. We expect that in coming future more and more users will be benefited from this website. We promise that we are devoted to update the information timely and provide you all more information of new discoveries in electronics.

Happy New Year 2010

On the behalf of elxproject.com team I would like to express my warm wish of New Year 2010 for you all our visitors and valuable members. Hope this year brings you all the exciting success in your life.

Happy New Year 2010

Dual Band Mobile Jammer for GSM 900 & GSM 1800

Communication jamming devices were first developed and used by military. This interest comes from the fundamental objective of denying the successful transport of information from the sender (tactical commanders) to the receiver (the army personnel), and vice-versa. Nowadays, mobile (or cell) phones are becoming essential tools in our daily life.

FM Transmitter Circuit

This circuit is a simple two transistor (2N2222) FM transmitter. No license is required for this transmitter according to FCC regulations regarding wireless microphones. If powered by a 9 volt battery and used with an antenna no longer than 12 inches, the transmitter will be within the FCC limits.

5x5x5 LED Matrix CUBE Controller

You might have seen many videos around you tube showing off crazy LED cubes, forming 3-D structures etc. But haven't find anything that explains how this is being done. Well searching over internet i found this great project made using a PIC 16F688 microcontroller used to control a 5x5x5 LED matrix cube.

The LED cube is made up from 125 LEDs arranged into 5 layers of 25 LEDs each. The display itself is multiplexed so instead of requiring 125 connections it requires one to each of the five layers and 25 to each LED in a layer making a total of 30. The cube is refreshed by a software interrupt routine with each layer active for 2ms, so the entire cube is refreshed every 10mS (100Hz). This results in a display with no visible flicker.

Only 8 I/O lines are needed to control the LED drivers for the cube which allows a tiny 14 pin PIC 16F688 microcontroller to control the whole cube. This micro has an internal 8Mhz clock and 4Kwords of program memory.

The complete circuit can be download in pdf format here: schematic
Firmware Download: LED Cube Matrix Driver
You can find more interesting videos and ready to burn hex file here: LED CUBE Controller

Artificial Plate Battery

Plate batteries for old tube radios are today only available with difficulty. However, step-up controllers for low DC voltages are everywhere. The circuits of these IC’s are, however, affected by disadvantages and complex wound inductance are needed. A further disadvantage of this solution is the transducer frequency; poor placing can cause audible interference.

Plant Watering Watcher

This circuit is intended to signal when a plant needs water. A LED flashes at a low rate when the ground in the flower-pot is too dry, turning off when the moisture level is increasing. Adjusting R2 will allow the user to adapt the sensitivity of the circuit for different grounds, pots and probe types.

Smart Trailing Socket

This circuit consists of a Trailing Socket (also called Extension or Distribution Socket) or similar device where two, three or more sockets (depending on the box dimensions and on constructor's needs) will be powered only when a current flows in the Control Socket.