Sajee tronics

Description: The ADXL345 is a small, thin, low power, 3-axis accelerometer with high resolution (13-bit) measurement at up to ±16 g. Digital output data is formatted as 16-bit twos complement and is accessible through either a SPI (3- or 4-wire) or I2C digital interface. The ADXL345 is well suited to measure the static acceleration of gravity in tilt-sensing applications, as well as dynamic acceleration resulting from motion or shock. Its high resolution (4 mg/LSB) enables measurement of inclination changes less than 1.0°. Several special sensing functions are provided. Activity and inactivity sensing detect the presence or lack of motion and if the acceleration on any axis exceeds a user-set level. Tap sensing detects single and double taps. Free-fall sensing detects if the device is falling. These functions can be mapped to one of two interrupt output pins. An integrated, patent pending 32-level first in, first out (FIFO) buffer can be used to store data to minimize host processor...

Usually, low-priced home stereo power amplifiers don’t have output level indicators. An output power level indicator can be added to each channel of these stereo power amplifiers. As low levels of the output power are not disturbing and damaging to the people, there is no need to add a preamplifier and low-level detector before IC LM3915. But you should know when the output power becomes considerably high. Here we present a very simple, low-cost stereo-level indicator circuit for home power amplifiers with power rating of around 0.5W. The circuit is built around two LM3915 dot/bar display driver ICs (IC1 and IC2). LM3915 senses analogue voltage levels to drive ten LEDs, providing a logarithmic 3dB/step analogue display. The voltage levels below 1V are not important because these correspond to a low level of the audio signal. Similarly, input voltage levels above 30V correspond to too high levels of the output power, which are not applicable for home power amplifiers. So the voltage...

While driving on highways, motorists should not exceed the maximum speed limit permitted for their vehicle. However, accidents keep occurring due to speed violations since the drivers tend to ignore their speedometers. This speed checker will come handy for the highway traffic police as it will not only provide a digital display in accordance with a vehicle’s speed but also sound an alarm if the vehicle exceeds the permissible speed for the highway. The system basically comprises two laser transmitter-LDR sensor pairs, which are installed on the highway 100 metres apart, with the transmitter and the LDR sensor of each pair on the opposite sides of the road. The installation of lasers and LDRs is shown in Fig. 1. The system displays the time taken by the vehicle in crossing this 100m distance from one pair to the other with a resolution of 0.01 second, from which the speed of the vehicle can be calculated as follows: As per the above equation, for a speed of 40 kmph the displa...

This circuit is designed for indicating over-speed and direction of rotation of the motor used in mini hand tools, water pump motors, toys and other appliances. A 12V DC motor (M1) is coupled to the rotating part of the appliance with a suitable fixing arrangement. When the motor rotates, it develops a voltage. This over-speed indicator is built around operational amplifier CA3140 (IC1). Set the reference voltage (depending on the desired speed) by adjusting preset VR1 at pin 2 of IC1. When the voltage developed at pin 3 of IC1 is higher than the reference voltage at pin 2, output pin 6 of comparator IC1 goes high to sound piezobuzzer PZ1 and light up LED3. The rotation indicator circuit is built around AND gate 74LS08 (IC2). Pin 2 of gate N1 goes high when the motor rotates in forward direction, while pin 1 of gate N1 is pulled high via resistor R2. When both pins 1 and 2 are high, output pin 3 of gate N1 goes high to light up LED1. Similarly, pin 5 of gate N2 goes high when the m...

The mouse and the Keyboard form the standard input unit for a Personal computer. The QWERT keyboard which is used in the PC comes with a PS2 connector or USB port connector. The PS2 keyboard uses a simple synchronous serial protocol using only two wires for communication. Due to its simplicity the PS2 keyboards are widely used with simple microcontroller based boards also. The PS2 keyboard always acts as a slave device which can send the equivalent ASCII value of the key which has been pressed to its master device which can be a PC or a microcontroller. The  ZigBee  is the name of a wireless protocol maintained by the IEEE 802.15 standard. This is a protocol specified for wireless Personal Area Network (PAN) using low powered wireless transceivers. There are already wireless transmitter and receiver modules which can do point to point communication. The Xbee is the brand name a wireless transceiver device which works on the ZigBee protocol and can form PAN networks. ...

embRACE , a game developed on the embedded platform, entirely coded in assembly language. The game has been programmed on an ATMega16 micro-controller, interfaced with a 16x2 LCD display module. The game possesses an interactive user interface and exclusive features like:  -Main Menu  -Pause Menu  -Real Time Score display  -Life Indicator LEDs  -Non-volatile High Score storage  The LCD display uses custom LCD characters to display various characters in the game whose generation timing in the game is totally randomized by the code. In the design and code phase it has particularly been taken care of that the overall game is interesting and substantially user-interactive. Moreover, the assembly language programming has majorly contributed towards the development of a more optimized, machine-friendly and effective code. File Attachment:  embRACE_Hex.rar        .

This project is a reference to budding engineers or a helping hand to those who willing to work and  interface a GPS Receiver with microcontroller  and making their own channel to communicate with satellite, seeking for some useful information from satellite to make a effective and efficient system. Before we check all the details of this project, here is the  final implemented circuit diagram of  longitude and latitude display system using GPS and AVR microcontroller . GPS In a simplest way ‘The  Global Positioning System  (GPS)’ is a satellite-based navigation system that consists of 24 orbiting satellites. This satellite transmits an amount of information in string format (e.g.: latitude, longitude, altitude, time etc.) which we are going to cover further . GPS Receiver GPS Receiver received the information in string format, transmitted by Satellites, which uses this information to calculate different parameters between it and satell...

Here is a simple calling bell circuit that can be used in small offices to call the office boy using an existing intercom system. The office boy can be called from up to nine locations where extension lines are installed. The system is connected to a dedicated extension for the office boy. Whenever someone needs the office boy’s assistance, he can dial the office boy’s extension number through the intercom and then press a key to indicate his location number (say, 5). This number will be displayed on a seven-segment display and at the same time a bell will sound to alert the office boy. Pressing a switch will clear the display. The entire circuit can be divided into two sections: ring cease cum bell timer, and decoder cum display. The ring cease and bell timer section is built around optocoupler MCT2E (IC3), NE555 timers (IC4 and IC5) and a few discrete components. The optocoupler is used to trigger the timers (IC4 and IC5). Both the timers are wired in monostable mode. The time per...