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  1. gg4rest

    Measuring 10mV analogue signal

    The first question is what is the frequency of the signal you are measuring? How fast is it typically changing? You need to know this because you will have to handle it with filtering otherwise you will get aliasing when you sample it. The second question is how fast do you want to sample it? Do...
  2. gg4rest

    sensors:pre final year engineering mini pojects(urgent)

    What type of sensors are you interested in? There are pressure sensors, force sensors, EMG sensors. Are you supposed to control something with these sensors or simply get readings from them?
  3. gg4rest

    SIMPLEST LIE DETECTOR

    You may want to purchase some electrolytic gel to put on the electrodes (the kind used for electromyogram and electrocardiogram sensors). Medical supply stores should have this. This will reduce the contact resistance between the electrodes and the person's hand. That will allow more precise...
  4. gg4rest

    Radio Frequency Communication (RF)

    This link might be helpful for RS-232/422. It shows how to daisy-chain RS-232 which might be okay. I'm not sure about your exact requirements. http://www.maxim-ic.com/appnotes.cfm/appnote_number/723 You could also consider a 4-20 mA current loop. They use these in industrial facilities due to...
  5. gg4rest

    Free sample chips!

    I have another tip for everyone. If there is a part that isn't a sample, you can usually perform a "escalation" where you can get more expensive parts if you can justify why you need the part pretty well. I got a DSP that way because I said the microcontrollers I used here insufficient for the...
  6. gg4rest

    Free sample chips!

    If you put your university as the company, they likely will give you the parts. I have done the same many times and got my parts.
  7. gg4rest

    want circuit diagrame

    A mobile phone jammer? I'm not sure the licensing authority would be too happy about that.
  8. gg4rest

    Radio Frequency Communication (RF)

    You are planning on using RS-232 over a distance of 100 meters? I am quite sure it won't be able to do it without difficulty. You should use RS-422 instead. RS422 offers greater noise immunity and greater communication distance than RS232. RS422 wiring can be up to 4,000 feet (1.219 km) in...
  9. gg4rest

    Making PCBs with magazine's paper

    Just thought I would post this link. It seemed relevant and quite descriptive on how to use a laser printer with some paper from staples. http://www.fullnet.com/u/tomg/gooteepc.htm
  10. gg4rest

    Radio Frequency Communication (RF)

    I am not sure of the regulations of your country; however, I found this on a site (see below). ISM2.4 and ISM5.8 are for the 2.4 GHz and 5.8GHz so they don't apply to you. You need to look at the dBm that the device gives (should be variable) and the gain of the antenna you are using. "Summary...
  11. gg4rest

    Radio Frequency Communication (RF)

    I suggest using the ISM band (probably 900 MHz), the same one used by cordless phones. Texas Instruments offers some ISM RF ICs for transmitting and receiving. I don't know if you will get a 100 meter range though. You could test it if you had a cordless phone. Get someone to call you and then...
  12. gg4rest

    Electronics & Robotics

    There is also the stiquito. It uses muscle wires to move and is quite light and cheap; however, it is also limited in its abilities to move. http://www.stiquito.com/
  13. gg4rest

    Digital temperature control

    Analog Devices (www.analog.com) has several analog and digital temperature sensors and several of them are offered as free samples and the datasheets have some example circuits.
  14. gg4rest

    Electricity

    I am assuming this is a textbook question so it is drawn incorrectly as Ante pointed out, there should be "dots" to show that they are connected. However, assuming they are connected and I did my math and circuit reduction right. And assuming that p.d. stands for Potential Difference (ie...
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