Rocketdock
Rocketdock is a software which creates a shortcut menu on top of the desktop, like in the below image,
Sunday, 16 February 2014
Monday, 3 February 2014
Sunday, 19 January 2014
Simple Fire Alarm Circuit
Simple Fire Alarm Circuit
Here is a simple fire alarm circuit based on a LDR and lamp pair for sensing the fire.The alarm works by sensing the smoke produced during fire.The circuit produces an audible alarm when the fire breaks out with smoke.
When there is no smoke the light from the bulb will be directly falling on the LDR.The LDR resistance will be low and so the voltage across it (below .6V).The transistor will be OFF and nothing happens.When there is sufficient smoke to mask the light from falling on LDR, the LDR resistance increases and so do the voltage across it.Now the transistor will switch to ON.This gives power to the IC1 and it outputs 5V.This powers the tone generator IC UM66 (IC2) to play a music.This music will be amplified by IC3 (TDA 2002) to drive the speaker.
The diode D1 and D2 in combination drops 1.4 V to give the rated voltage (3.5V ) to UM66 .UM 66 cannot withstand more than 4V.
Notes:
Digital Sound Recorder with AVR and DataFlash
Digital Sound Recorder with AVR and DataFlash
Features
• Digital Voice Recorder
• 8-bit Sound Recording
• 8 kHz Sampling Rate
• Sound Frequency up to 4000 Hz
• Maximum Recording Time 4 1/4 Minutes
• Very Small Board Size
• Less than 700 Bytes of Code
Introduction
This application note describes how to record, store and play back sound using any AVR microcontroller with A/D converter, the AT45DB161B DataFlash memory and a few extra components.
This application note shows in detail the usage of the A/D Converter for sound recording, the Serial Peripheral Interface – SPI – for accessing the external DataFlash memory and the Pulse Width Modulation – PWM – for playback. Typical applications that would require one or more of these blocks are temperature loggers, telephone answering machines, or digital voice recorders.
The AT45DB161B DataFlash is a 2.7 volt only, Serial-interface Flash memory. Its 16 Mbit of memory are organized as 4096 pages of 528 bytes each. In addition to its main memory, the DataFlash contains two SRAM data buffers of 528 bytes each. The buffers allow a virtually continuous data stream to be written to the DataFlash.
The AT45DB161B uses an SPI serial interface to sequentially access its data. This interface facilitates hardware layout, increases system reliability, minimizes switching noise, and reduces package size and active pin count. Typical applications are image storage, data storage and digital voice storage. The DataFlash operates at SPI clock frequencies up to 20 MHz with a typical active read current consumption of 4 mA. It operates from a single voltage power supply (from 2.7V to 3.6V) for both the write and read operations.
Its serial interface is compatible to the Serial Peripheral Interface – SPI – Modes 0 and 3, thus it can easily be interfaced to the AVR microcontroller.
In this application note the AVR AT90S8535 is used to take analog samples from a microphone and convert them to digital values. Its built-in SPI controls data transfers to and from the DataFlash. The PWM feature of the AVR is used for playback. The code size is very small, the application will therefore also fit into smaller AVR devices.
Source: Atmel Corporation
Source: Atmel Corporation
Design of a Voice Recorder using ADC Microcontroller
Design of a Voice Recorder using ADC Microcontroller
The C8051F411 offers a versatile, small (5 x 5 mm), highly integrated, low-power solution for voice applications. The 12-bit ADC and DAC allow for reasonable quality sound at a 8 kHz sampling rate, and the Hardware Accumulation and Burst Mode features of the ADC provide for further improvements with small processing tradeoffs. The Suspend mode operating feature allows the voice recorder to “sleep” while idle, saving power in a similar fashion to the traditional 8051 Stop mode, but still allows the recorder to wake and respond to the user without a hardware reset. This document describes the solution for a telephone-quality voice recorder using the C8051F411.
This document includes the following:
- A description of the system hardware and software
- Usage notes and customization considerations
- A schematic, bill of materials, and detailed layout diagrams
- The implementation of the software showing how to sample, compress, store, and play back a voice signal
Key Points:
- Because of its small size, versatile peripherals, and low-power features, the ‘F411 readily lends itself to battery operated voice applications.
- The system uses a DPCM (Differential Pulse Code Modulation) compression algorithm for data storage to extend the total recording time.
- The recorder takes steps to minimize power usage while active and uses the “Suspend” feature of the ‘F411 to reduce power consumption when idle.
Source: Silicon Labs
Wireless Electrical Appliances Control System Using IR Communication
Wireless Electrical Appliances Control System Using IR Communication
Domain : Embedded Systems, Power Electronics,
Software : C, Keil, Proload
Power Supply : +5V, 500mA Regulated Power Supply
Display : 7-Segment
LCD : HD44780 16-character, 2-line (16X2)
Input : IR signal from Remote control (RC5)
Crystal : 11.0592MHz
Switching Loads : 6
Applications : Industries, Offices, Hotels. Banks, Hospitals
Controlling electrical appliances through IR remote is interesting and very useful application. This system is widely used in industries, offices, Banks, hotels, hospitals, and display boards. In this project, IR is used for controlling any appliance in an industry by controlling the loads.
IR rays are transmitted through remote and these rays are received by a receiver named TSOP 1738. Here, in this project two microcontrollers are used, one for master SECTION and other for slave section. The IR rays received by TSOP are given to the master section. from master section, IR signals are given to slave section for LED indication and are displayed on 7-segment for the respective loads. Now, from MASTER section, the loads are controlled through triac driving circuit. In the triac driving circuit, as the controller cannot provide sufficient current, MOC’S are used to drive these triacs and these triacs in turn are connected to loads. Next, in the slave section, the door opening and closing is done through a stepper motor rotating in clockwise and anticlockwise direction respectively. In this, for every respective load on activation, a message is shown on 7 segment display as load1 , load2, load3, load4, load5, load6.
The uniqueness of this project is, a stepper motor is also can be controlled by IR signal. Using “>” key on remote, the door can be opened, and using “<” key, the door can be closed. This project uses regulated 5V, 500mA power supply. 7805 three terminal voltage regulator is used for voltage regulation. Bridge type full wave rectifier is used to rectify the ac out put of secondary of 230/12V step down transformer.
Advantages:
Easy to operate
Power saving
Best suitable for Bed-ridden patients
Scopes for Advancements:
Auto speed control based on temperature can be implemented using a temperature sensor.
Applications:
Industries, Hotels, Hospitals, Shops, Banks and offices
References:
Text Books
Know about Infra-Red By Cruis Leanardo
Zero Crossing Voltage and Applications By Morris Hamington
Magazines
Electronics for you
Electrikindia
Let us Go Wireless
Digital Visitor Counter
Digital Visitor Counter
Digital visitor counter is a reliable circuit that takes over the task of counting Number of Persons/ Visitors in the Room very Accurately.
When somebody enters into the Room then the Counter is Incremented by one and when any one leaves the room then the Counter is Decremented by One. The total number of Persons inside the Room is displayed on the seven segment displays.
The microcontroller does the above job by receiving the signals from the sensors, and this signal is operated under the control of software which is stored in ROM
Computer Controlled Automated Small Vehicle
Computer Controlled Automated Small Vehicle
This paper represents a computer controlled small vehicle. This kind of vehicle can move in a predefined path without human operator intervention and can collect data from the surrounding environment. This data has been processed by a well structured hardware and software. After processing the received data is sent to the vehicle to move it in its correct path. This type of vehicle can be used in variety of application such as military spying, fire fighting system etc.
Introduction
A 6 volt motor operated small vehicle is developed which is fully computer controlled. The developed system has been interfaced with PC through standard parallel printer port of an IBM compatible Pentium I processor. Micro-switch sensors /1/ has been attached with the body of the vehicle at different locations to collect data from the surrounding environment.
Five sensors are used for this purpose and they are attached on front, back, lower front and two sides of the vehicle. Data from the vehicle is serially sent towards the PC through a transmission line using serial data transmission standard. A software has been developed using ‘TURBO C’ language to process this data and suitable command has been sent serially towards the vehicle to move it in its correct path. The complete system is shown in block diagram in the download.
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