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    Finding the unknown coordinates of a point, knowing its difference of distances

    Hi everybody, Assume that I have 3 "reference points", which are some fixed points with known coordinates (known location on x-y plane).Take "A" as an unknown point (I mean a point that I don't know its coordinates). If a system measures the "difference" of distances from A to that "reference"...
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    Problem in measuring distance with time-of-flight of radio waves

    Hi dear friends, I've decided to build a simple system that measures the distance between a RF transmitter and a receiver (range finding). My idea is based on measuring the Time-Of-Flight of the radio wave ,with a digital circuit (also a microcontroller may be used). I need an accuracy about 10...
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    Problem with microphone preamplifier circuit

    Hi, Please have a look at this circuit which I use to amplify the output signal of a capacitor microphone. I watch the output of the circuit on a oscilloscope, but it seems to be random noise.When I speak to the mic I can't see anything similar to audio signal on the output. Only when I hit the...
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    [SOLVED] Problem with ARM microcontroller ethernet controller and DP23848 chip

    Problem with ARM microcontroller ethernet controller and DP83848 chip Hi, I've written a simple program for LPC1768 microcontroller (ARM Cortex-M3) in order to interface ethernet network, I just need to receive network packets at the first step. I've used DP83848C chip as the PHY (via RMII...
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    Color Sensor for Light

    Hi everybody. I need a color light sensor for my project, I mean a circuit or IC that is able to detect the color of the light (And I want to send its output to a microcontroller). I've seen some of the related projects on the internet which use three LEDs (Red,Green,Blue) to radiate light and...
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    Typical Refresh Rate of Small LCD Screens

    Hi everybody, I need to know the refresh rate of LCD screen of mobile phones. There must be a vertical refresh rate (vertical sync frequency) for mobile phone's LCD , like a PC LCD monitor, isn't it? My own phone model is Nokia 6120 but I couldn't find anything about its screen refresh rate...
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    Screen Refresh Rate of Nokia mobile phones

    Hi. In order to do a mobile programming project, I need to know the maximum refresh rate of LCD screen of my Nokia mobile phone. Actually I want to know how fast I can draw graphics on its screen (At what frequency it's possible to redraw the screen contents?). My phone model is Nokia6120. I...
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    How does a VGA monitor support different modes? (How to choose signal timings?)

    I'm confused by the signal timings for a VGA monitor. We know that the VGA standard have different modes (There is a different resolution, refresh rate and signal timing for each mode). Also the pixel clock frequency, at which the VGA adapter device must send the image data, differs for...
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    [SOLVED] Ultrasonic Transmitter/Receiver Circuits

    Hi everybody. I need to build a ultrasonic transmitter and a receiver for my project (The ultrasonic wave must be at a frequency about 30kHz). I wonder if I make a simple circuit that generates a 30kHz sine wave and I feed a typical loudspeaker with this signal, will it transmit ultrasonic...
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    How to record phone line calls using sound card?

    Hi everybody. I'm looking for a way to record voice of my phone line using the sound card of my computer. I know I can't directly connect the telephone to sound card input (because the voltage levels and impedance may not match). Please note I want to record phone just using the "sound card" ...
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    Problem with Maximum Forward Current of LED

    Hi. In some books and sites, it is said that the maximum forward current of a light emitting diode (LED) is about 30mA. But I exprimented with a LED and I noticed that it was working with 150mA forward current. When the LED was on, I measured the current using a digital ammetre and it was about...
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    Antenna Impedance of RF Modules

    Hi dear friends. I've purchased a RF ASK transmitter module and an ASK receiver module in order to build a remote control system. They are WXC810 and PCR1A chinese modules that work at 315MHz frequency. The problem is that the datasheet of module doesn't say anything about the impedance of the...
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    Problem with ASK reciever module

    Problem with ASK receiver module Hi everybody. I'm experimenting with an ASK receiver module (PCR1A 315MHz module. It's Chinese,I think). I just tested the ouput of module in absence of any signal (without any transmitters nearby). I expected the output (Data pin of module) to be constantly low...
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    On-Off Keying Modulation for remote control

    Hi. I've been trying to build a simple radio remote control system. I wish to use microcontrollers (AVR micros) as the heart of transmitter and reciever circuits. The system is going to be simple, it transfers just two different commands (I represent them using binary codes). Also the distance...

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