Low-Voltage Linear Taper Digital Potentiometer

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The MAX5394 single, 256-tap volatile, low-voltage linear taper digital potentiometer offers three end-to-end resistance values of 10k?, 50k?, and 100k?. Potentiometer terminals are independent of supply for voltages up to 5.25V with single-supply operation from 1.7V to 5.5V (charge pump enabled).

User-controlled shutdown modes allow the H, W, or L terminal to be opened with the wiper position set to zero-code, midcode, full-code, or the value contained in the wiper register. Ultra-low-quiescent supply current (< 1µA) can be achieved for supply voltages between 2.6V and 5.5V by disabling the internal charge pump and not allowing potentiometer terminals to exceed the supply voltage by more than 0.3V. The MAX5394 provides a low 50ppm/°C end-to-end temperature coefficient and features a SPI serial interface.
[source: maxim-ic.com]

Web-Based programmable logic control (PLC)

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Today there are very rapid development of technology and progress, these developments require humans to continue to innovate to create tools that can help in performing daily activities.

Many activities to do outside the home who sometimes have to leave home until the days and – days. Usually we always turn out the lights when leaving the house empty. This could cause the waste of electrical energy consumption for lighting during the day alive, and will also lead to vulnerability to theft because the house is seen in a state of no activity. To overcome this, the authors sought to create control systems electrical installations are cheap and easy to apply.
This application which will manage all electrical systems to manipulate the situation as if uninhabited, except that this application will replace our work in the light turn on and off every day. Therefore, the authors tried to examine and make the “Applications Web-Based Control Electrical Equipment OpenWRT”.
OpenWRT is an operating system (actually more properly called Firmware) that can be installed (more precisely planted / in-embedded) on a wireless radio device. OpenWRT is to replace the function of a PC is usually used in the application of programmable logic control (PLC), as an OpenWRT operating system can be installed with various applications such as web server and PHP. With this capability makes the “Applications Web-Based Control Electrical Equipment OpenWRT” is very flexible and low cost. Another capability of this application is able to control your home from anywhere are, as long as it can be connected to the internet.

Author : puguh

Copyright: Puguhwah@yahoo.com



AVR Embedded Web Server

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The AVR embedded web server reference design is designed for integration in digital
equipment. The AVR embedded web server can be plugged into any Ethernet interface and communicate wi th a standard web browser.

Suppose the AVR embedded web server is embedded in several units in a house. Every
server is connected to the network. A computer located at home as on Figure 2 controls
all devices and can receive requests from other computers on the Internet. The web
server is identified by its unique IP address and can be controlled remotely from anywhere
in the world as long as the authorization is in order.

See More Atmel Datasheet

Build Own RFID circuit

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The terminal of the coil is connected to the GP4 port. In order to transmit data to the RFID reader, we have to modulate the low frequency carrier by changing the coupling between the reader and tag antennas. We can achieve this by switching the GP4 as input

The IO pins and the external coil form a LC resonant circuit and act as an antenna. This antenna will pick up the carrier generated by the RFID reader.

The recovered carrier is rectified thanks to the bridge formed with the clamping diodes, feeding back the result signal to the power supply of the microcontroller.

Download :
1. Firmware RFID

2. Other Schematic

source :http://scanwidget.livejournal.com/32928.html

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