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Welcome to Electronics and Electrical Engineering Laboratory.

Car Motor Controller Circuit by using infrared

This simple add-on ckt (circuit) enables remote control switching on or off of battery-operated toy cars with the help of a TV/ video/Radio remote control handset operating at 30–40 kHz. This ckt diagram is very easy to build and also low cost . This is very important circuit any many where u can use this ckt just change some configurations.


Aeronautics Educator Guide

Robotic - Aircraft

This guide presents the basic science of aeronautics by emphasizing hands-on involvement, prediction, data collections and interpretation, teamwork, and problem solving.



Rain Detector

Science - Science Project

This circuit diagram is very easy to make a project. Its a very interesting project.


18V FM Transmitter

Radio - FM-Radio Transmitter

 att wireless communication

 Circuit Description : 

   The circuit is basically a radio frequency (RF) oscillator that operates around 100 MHz (100 million cycles per second). Audio picked up and amplified by the electret microphone is fed into the audio amplifier stage built around the first transistor. Output from the collector is fed into the base of the second transistor where it modulates  the resonant frequency of the tank circuit (the coil built into the circuit board and the trimcap) by varying the junction capacitance of the transistor.  Junction capacitance is a function of the potential difference applied to the base of the transistor. For a  FULL DETAILED technical description of the operation of two stage FM Tx like this one see:


Crystal-Controlled Time-Base Generator for a Frequency Counter

Automotive - Time-base

Many where we need to count frequency. If we want to make a digital frequency counter than  needs a time-base generator to count the frequency with high resolution. Commonly , a crystal-based oscillator with divider IC  or a similar circuit in the form of an ASIC (application-specific IC) is used for time-base generation.

Here we’ have represent a simple circuit for accurate time-base generation using the readily available 3.5795MHz crystal normally used in telecommunication equipment. The 3.5795MHz crystal is used in conjunction with a CD4060-based crystal oscillator-cum-divider (IC1). The crystal frequency is divided by 512 by IC1, which is further divided by 7 by CD4017 (IC2). IC2 is reset as soon as its Q7 output goes high.Thus the crystal frequency is divided by 3584, giving the final output frequency of around 998.8 Hz. This frequency can be trimmed to exactly 1 kHz with the help of trimmer capacitor VC1 as shown in the figure. The 1kHz signal can be further divided using decade counters to generate the required time period.

Note:  To generate needed to gate for use in a frequency counter circuit, the final oscillator output require to be followed by a toggle flip-flop.e.g. a 1kHz clock, when applied to a toggle flipflop, will generate gates with 1-sec ‘on’ period and 1-sec ‘off’ period.

This circuit is estimated to cost below TK 100.

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