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Everything posted by mugsby

  1. i'm thinking of starting work on some projects with someone else, anyone here live near maryland? if any students are interested in a startup (student myself) please reply. thanks
  2. happy 2007, i think it's goingto be a fun year! :D
  3. that first schematic is a chopper circuit, they were used in the first car radios to provide v+ for TUBES, very noisey!
  4. i remmember lots of the chip companys used to give these away, ti, analog devices, linear technology, ect. i have older ones from 1995-98 i'm looking for new ones, anyone have links where these can be ordered from? also does anyone knows where to get FREE recent data books?
  5. if this is something that is going to be for sale wouldn't be easyier(and cheaper) to use the output from the 7 segment driver on a $5 clock?
  6. see: http://en.wikipedia.org/wiki/Phase-locked_loop
  7. i was thinking of building a linear power supply but i have to wonder about if just grounding a shield will be enough. if you are in a sealed box and throw a tennis ball against one of the walls what happens outside of the box, thinking along those lines ??? lol
  8. are you talking about the phase change between voltage and current?
  9. 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 ???
  10. ok hook it up stright away and tell me if it works :P, i made the same thing with a few off the shelf parts thanks anyway.
  11. 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
  12. parts-express sells 3 conductor mic wire that might work.
  13. thanks for looking but what i'm looking for has ttl output, with just a photo-trans i'd have to add more parts, thats what i'm trying to avoid. thanks again.
  14. jfyi, i test at what voltage it takes to feel an electric shock on myself, 42-45 volts depending on the moisture on my fingertips :D
  15. 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.
  16. ethernet is balanced, you need to change that first.
  17. you might want to read up on the doppler effect.
  18. output to what? it looks like a one stage receiver.
  19. the cutoff in a transistor is determined by the base junction capacitance and the current gain bandwidth along with the beta gain and also the class in which it's biased or if purely switching.
  20. it depends on the type of filter -3db is just a number thrown out there, the actually cutoff depends on the application.
  21. 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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