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  1. SM2GXN

    rf coil

    MP I agree, it's a good way to learn how component values change with frequency and bandwidth  :) I'm sorry arsal_uet but audioguru is right about the filter, strong nearby signals from other cellular phones or base stations would probably be detected by your circuit. if the frequency would be...
  2. SM2GXN

    rf coil

    Rl= load resistance. To build a band pass filter 800-900Mhz is not an easy task I would say that some RF experience is needed. MP it's a good calculator but as you probably know both C and L involved in a band pass filter like this aren't what the average hobbyist usually deal with, I'm not an...
  3. SM2GXN

    Bigginers Handbook

    Hi logan_dslasher! Yes it's for free you just have to click for free download wait 45 seconds, fill in three letters as shown and click download.  ;)
  4. SM2GXN

    Another Oscilloscope Question

    That is one of the best notes written about scopes and probes, cynicmonster do yourself a favour and read them  ;) Some of its content might not be written for a newbie but there is some useful reading for oscilloscope owners and for those who plan to buy one.
  5. SM2GXN

    rf coil

    Don't know if you have any particular circuit in mind but here is a link where you should start your reading to get "some" understanding in resonant circuits, there might show up better places if you search google. http://www.ibiblio.org/obp/electricCircuits/AC/AC_6.html Oscillators is a huge...
  6. SM2GXN

    Another Oscilloscope Question

    No you wont damage you scope just because the probes has more or less bandwidth than your scope. There is cheap good probes on the market for $50-$70, buy probes that have switchable attenuator, 1X 10X. Check this link, it's quite a common probe dc-150Mhz http://www.farnell.com/datasheets/32925.pdf
  7. SM2GXN

    CRT monitor

    Thank's Ante! The 2SC5302 doesn't have any damper diode built in between collector and emitter. If you have unsoldered all legs there should be an infinite resistance between collector and emitter if not then your transistor is smoked, be sure that no legs are in contact with the the pcb traces.
  8. SM2GXN

    rf coil

    RF Coil is just what it sounds like it's simply a coil and at RF usually one part of the oscillator that determine its frequency.
  9. SM2GXN

    ANTENNA RADIATION PATTERNS

    Hi prateeksikka! Just in case you want to play with another software, MMANA 2.03 is a very nice and accurate antenna analyzing software that will show radiation pattern in 3D, I've used it for a long time and it's for free  ;) http://mmhamsoft.ham-radio.ch/
  10. SM2GXN

    CRT monitor

    Is DE9704 the marking on your transistor? I'm sorry but never heard of it please check again  ;)
  11. SM2GXN

    CRT monitor

    C5302=2SC5302 these are japs :) No you can not just swap to another transistor unless you know it is an true replacement. Check the transistor you got in your spare monitor and let me knowwhat type it is.
  12. SM2GXN

    CRT monitor

    Sounds like you figured out that the HOT was the culprit, about you question, it depends on where you live, what kind of  transistor is it?
  13. SM2GXN

    Modifying RF Light Switch

    You are right Ante most probably the RF part need more than 9volts but somehow they will initially need more than 12 volts for the relay to activate, some battery powered circuits I've seen had some kind of momentarily higher voltage supplied to the relay to activate it and than dropping the...
  14. SM2GXN

    Where do I look to fix a monitor ghosting problem?

    You are right it has nothing to do with a magnetized crt, I can't really come up with any bright idea. It sounds though that your problem could be temperature related, have you tried to switch to another resolution? If the focus adjustment potentiometer goes bad it usually show up either partly...
  15. SM2GXN

    Modifying RF Light Switch

    Hi AdamUp! It depends on what the rest of this device want  ;D a relay can be forced to activate by for a short time supply a voltage close to 24 volts, this voltage can probably drop down to 12 volts and still keep the relay activated so it might work with a 9 volt battery, try it. Well that...
  16. SM2GXN

    CRT monitor

    I don't even know if your monitor has step down converter, a schematic would be a great help, the step down converter supply collector voltage for the HOT, if this converter doesn't work the voltage to the HOT is usually to high and will result in destruction. Use high res scale I think you...
  17. SM2GXN

    CRT monitor

    EHT= high tension. Some of these horizontal output transistors (HOT) have damper diode built in between collector and emitter that might be the reason why you get .6V, try to swap testleads and if you get same .6 volts the transistor is probably shorted, measure resistance across...
  18. SM2GXN

    Viewsonic E40

    Hi ALi! Hopefully this is what you are looking for  ;) Chasis_JD144.pdf
  19. SM2GXN

    Where do I look to fix a monitor ghosting problem?

    Don't think it is a good idea to degauss a crt with a loudspeaker magnet it will get even worse and if you place a magnet to close to the front of the crt you can actually damage the crt and you are looking for real trouble. Degaussing is usually done by running ac current throgh a coil at the...
  20. SM2GXN

    power on the usb frm pc!!!

    Yes you are right, 5 volts is nominal, if more than 100mA is to be drawn from the USB the device should be powered from an auxilary supply but some USB,s will deliver up to 500mA. Don't know if the USB has any type of currrent limiter so one should be careful.
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