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  1. poor mystic

    Sending a voltage signal upon receiving another signal

    Umm... So are you planning to use a microcontroller to achieve a short delay and nothing else? I do realise that microcontrollers are the way of the future but this seems to me like using a good warp-capable spaceship as a letterbox. I'd have used a timer chip, such as a 74LS123 or even a 555...
  2. poor mystic

    Army Surplus power supply..

    :) Hi My tutor discussed mag amps, I have only ever seen one example which had been used to regulate current to a lamp. I don't feel that a simplistic explanation will help you but a simple one might. Wikipedia has a pretty readable article. Why not try Wikipedia, and come back with specific...
  3. poor mystic

    RF Generator with 1600Vdc output 20KW

    :) Hi! Are you suicidal? At least join a radio club, get your licenses, and THEN get very senior, professional engineer level advice. Please do not f about with this equipment.
  4. poor mystic

    cable sizing

    Yeah. 900 meters. Frankly, I wouldn't. That is, I wouldn't try and get around the regs. Sometimes you just have to bite the bullet and pay, and I'd guess that this is exactly one of those times. The regs aren't there to ensure electricians get plenty of work, they're not there to make money for...
  5. poor mystic

    Trying to make analogue sound to lcd?

    My old phone had "speech to text conversion". If such a phone is taken into a noisy environment, with the right kind of noise, it will sometimes seem to pick up a word. It's random. Such words are not messages from another dimension. There are lots of these pseudo-technologies. Radionics is...
  6. poor mystic

    using an ohmmeter

    :) "Internal" means that sometimes 2 or more internal turns of a coil (say a motor magnet coil or a transformer coil) can become fused together. An "external" short is one where the short circuit is in the wiring to and from the coil. Both kinds of short circuits cause faults.
  7. poor mystic

    cable sizing

    Hi:) Before anybody could offer any reasonable opinion they would need to know what exactly you intend to power from the supply. You need to assess all your loads and provide a worst-case (ie maximum) figure for current drain. I don't know anything about the engineers you consulted but any good...
  8. poor mystic

    Coils

    :) A drawing might help us a lot. Your design aims and criteria would help, too. There certainly is a method for calculating the magnetic flux in a given magnetic circuit. The most important result in my opinion is that air gaps are like multi-megohm resistors, while iron cores are like good wire.
  9. poor mystic

    Immediate hire-new job

    I suppose you live in some particular part of this world?
  10. poor mystic

    My New Toy

    :D I'm pretty sure that's just what Steve looks like. ( I met him over the eclipse last year in Northern Queensland and he looked like that then)
  11. poor mystic

    Wanted: Reference Wireless World magazines

    Can we consult the back issues online, or again - do you have a library service please? The particular issue I wanted to consult was March 1984, and the article was about a voltage multiplier by Purves and one other.
  12. poor mystic

    Coils

    I hesitate to say that another member is mistaken, but the thickness of the wire has no direct effect on the magnetising force. Apologies, Chris! If a fairly technical discussion suits you, try: http://en.wikipedia.org/wiki/Electromagnet Otherwise, magnetic force is proportional to N*I. N is the...
  13. poor mystic

    LH2715 Advanced Micro Devices

    And I tried Bing. http://www.repairfaq.org/REPAIR/F_Obsol_IC.html#OBSOLIC_003 is a link to a page containing this paragraph: " Obsolete AMD ICs Luke Systems International Tel: 818-991-9373 Tel: 206-863-8506 Fax: 818-991-4654 E-mail: [email protected] (From Laura Luft) Contact for...
  14. poor mystic

    LH2715 Advanced Micro Devices

    :) Hi Shrtnd I would hope that the Library of Congress has a copy. I'm pretty sure they're supposed to collect everything ever published in the USA. However I've never used that library myself, so I don't know what they're like to deal with.
  15. poor mystic

    westing house tv works but smells of smoke

    :) Also: When an electric arc occurs in air, some of the carbon dioxide is dissociated through electrolysis. The resulting ultrafine soot is a good conductor and can cause baffling faults.
  16. poor mystic

    Sending a voltage signal upon receiving another signal

    :) The book you want is: "The Art of Electronics"; Horowitz and Hill The book is so well written, and with such wonderful exclusion of bs - I think you're going to have fun with this!
  17. poor mystic

    looking to go to school for electronics .. scared

    :) JMW talks good sense, especially about loans. You could do an electrical trade, and get an electronics hobby going on the side with supplementary night school. In becoming a competent electrician you'll find yourself in high demand, and extending your fault-finding skills into electronics...
  18. poor mystic

    Op Amp HiFi Project

    Hi :) Speakers are rated according to how much power they can handle. A 10W speaker won't be damaged by 10W signals, but a 5W speaker probably will be damaged. Because a higher-power-rated speaker is usually larger, it's common to find that it will also produce better bass. Any larger speaker...
  19. poor mystic

    Ultrasonic Transducers

    :) Hi I can't see how the circuit is supposed to work either. Why the 2 identical transistor stages, with no gain? How does the transmitter circuit work, with its input seemingly taken from an external generator connected to an amplifier's output? And Kris' comment about the time constant of...
  20. poor mystic

    Op Amp HiFi Project

    You'll need at least 10W rated capacity in the wall wart.:) edited: ... and that doesn't mean 20W wouldn't be better.
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