A previous Design Idea describes a circuit that uses an astable multivibrator to drive an LED (Reference). The circuit in Figure 1 uses a simpler alternative approach. The circuit uses a 2N3904 NPN transistor and a 2N3906 PNP transistor, which ...
02-07-2009
An ordinary automatic room power control circuit has only one light sensor. So when a person enters the room it gets one pulse and the lights come ‘on.’ When the person goes out it gets another pulse and the lights go ‘off.’ ...
01-07-2009
Introduction Sometimes you only need a simple and cheap RS232 terminal to get sufficient control over a PC or a RS232 device. There is no need, no space or even no power to place a monitor, a computer case and a keyboard. Maybe there exists also ...
30-06-2009
Here is a teleremote circuit which enables switching ‘on’ and ‘off’ of appliances through telephone lines. It can be used to switch appliances from any distance, overcoming the limited range of infrared and radio remote ...
26-06-2009
Ahmad Ayar The main source of power in a telecommunications system is -48 V. This source’s negative polarity and its large magnitude with respect to ground pose a challenge when designers want to use low-power ICs in the telecom ...
25-06-2009
T.A. Babu Not properly closing a refrigerator door will no doubt invite huge electricity bills. This gadget is an alert device that beeps if you leave the refrigerator door open for more than 20 seconds. When the door opens, the lamp illuminates ...
24-06-2009
Dave Vanden Bout In an application using a pin-limited microcontroller (MCU), I needed to scan an array of 16 buttons. The technique I used involved a series string of resistors of identical value connected between two bidirectional pins of the ...
19-06-2009
1. History Back in 2000 I built one small embedded device used for repairing of broken PC monitors. The motivation was to avoid the need of one operational PC near the technician desk used only to generate test rasters, because PCs are usually ...
18-06-2009
Write Cycle This is the simplest bus cycle. Target devices detect the start of the bus cycle by the FRAME# is asserted at the second clock. At a bus cycle is initiated, the bus comand and the address is taken in to each target device attached to ...
17-06-2009
Andy Collinson Description A circuit that offers visual indication of fluid level in a vessel, with a switchable audible alarm. Example uses would be to monitor the level of water in a bath or cold storage tank. Click, for enlarge The Conductance ...
15-06-2009
This project will explain how I build my new wattmeter. This watt meter will be able to measure power from 300 nW to 30 W @ (0-500 MHz). This wattmeter is based up on a dummy load of 50 ohm which can handle 50 W. The measurement will be displayed ...
15-06-2009
This is a simple project of a sundial wherein the pinion is replaced by a line LASER I took from a LASER level. The LASER is mounted on a RC servo which in turn is driven by a micro controller. The micro controller keeps the time and turns the RC ...
10-06-2009
To start off, this project was started when we received a grant from the Lemelson-MIT Program. (Josh, if you're reading this, we love you.) A team of 6 students and one teacher put this project together, and we have decided to put it on ...
25-05-2009
This is a simple capacitance meter which can measure capacitance value easy. There are some measurement methods for capacitance, at one time the capacitance was measured with a impedance bridge or a dip meter. Recently typical capacitance meters ...
25-05-2009
nuxie1 This simple circuit will let you check if a crystal oscillator is working. Simply connect the crystal between the two labelled points, and connect 5V+ to the power connector. If the LED lights, then it shows the crystal is functioning ...
21-05-2009
For around $30 in parts and a good amount of patience, you can have a completely open source and hackable mp3 player ready to go. It can be modified to accept serial commands, be embedded in an art project, used as the voice of your next smart ...
18-05-2009
Peter D'Antonio Daniel Riiff Introduction In the recent years, the MPEG Layer III (MP3) music compression format has become an extremely popular choice for digital audio compression. Its high compression ratio, and near CD quality sound make it a ...
17-05-2009
Abstract: The Network Time Protocol (NTP) has revolutionized the world. Suddenly one could have anywhere in the world accurate time and date. NTP is a simple UDP based protocol and can be implemented in a Microcontroller. Using the tuxgraphics ...
13-05-2009
Abstract: This is a continuation of the article An AVR Microcontroller Based Ethernet Device . The hardware is still the same (ENC28J60 + atmega88). The software is now updated to provide also a web-server. That is: instead of using a command line ...
12-05-2009
Abstract: Ethernet has traditionally been a quite complex interface. All Ethernet chips until today had 100 pins or more, where difficult to find in small quantities and difficult to use from a small microcontroller with little memory. Microchip ...
11-05-2009
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