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mugsby

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Posts posted by mugsby

  1. sometimes i like to listen to am radio and i have a computer that has to be next to the radio, the problem is that when both are on the computer jams the radio. i also seem to have a problem with the power line acting as an antenna for both the radio and computer on top of that the power wiring for the house is all wrong but i don't own it so won't fix that. i put a scope on the line and watched some digital hash modulate every time the hard drive or cdrom started working, i put some snubbers on the computer power supply and bypass caps on the outputs and that help a little. then i tested my body to see what it was picking up, digital hash like crazy, same as what i can hear on the radio. so i used a function generator and a coil from a hard drive head to test if i could muzzle the rf, that worked ok, now i'd just like some ideas on how to stop it. btw, this has never happened before like this, some reason it's out of control  ???

  2. well what your looking for will be two chips, one that does all of the processing (thats now likely to be in plcc unless you can pull something out of older equipment), and the power rf stage can be bought as a module or smt flatpack device, you still might have to build a separate receiver stage. if you open up a modern cell phone you can see just you condensed everything is using just a few chips, none hobby friendly.

    http://www.toshiba.com/taec/Catalog/Line.do?lineid=7240&familyid=25

  3. use a ganged pot to make a voltage divider, zeners as clamps and remove the cap from the soundcard and make it switchable, you might want to add a small bypass cap on the input as a precaution with hf's and a coupling transformer so you can test with ground mismatches.

  4. here are my thoughts,

    if your serious you need to get these things preferably in the order here:

    a old mr wizard book
    some bar magnets and a horse shoe with the fields marked with paint
    batterys
    a flashlight bulb
    some wire
    a dc moter
    a few switches
    a crystal radio kit
    the book "getting started with electronics" by forrest mimms
    a 100 in one kit
    a analog volt ohm meter
    the complete set of "mini engineers notebooks" by forrest mimms
    a 30 watt soldering iron
    a spool of 60/40 rosin core solder
    a diy pcb kit (radio shack)

    ok here are the first things you should build, most are in the books:

    a regulated variable power supply using a lm317
    an adjustable speed flashing led using a 555
    a powered mic using the power supply you made with a op-amp and a 386 power amp
    turn a fan on with a thermisistor circuit
    an active low and high pass filter using a dual op-amp as a pre speaker crossover
    a light sensor using a photo-transistor
    add a pass transisitor to your power supply to increase current
    use a photo-resistor to turn on a transisitor
    make a phone tap using caps and a coupling transformer


    after that get a "basic electronics course" book
    you can find your way after that :)

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