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Discussion in 'General Electronics Discussion' started by GHOSTOWLGRID, Dec 2, 2012.

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  1. GHOSTOWLGRID

    GHOSTOWLGRID

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    Dec 2, 2012
    Hello everyone.

    I have been trying to generate an analog square wave signal.

    I first looked into 555 timer circuits, but they are crude and useless to me.
    I have been looking into signal/function generators, and a found one that does 0-200 MHz sin wave. I know how to convert to a square wave. But the problem is I am limited to a max of 200 MHz.

    I want to be able to generate at least 0-1GHz analog signals into a wire.

    Does anyone recomend any programable microcontrollers or analog IC chips that can fit the task, I would like to just buy one, but I won't pay over 100 dollars for anything. (Everything I found was 400-1K dollars, thats just overpriced).

    My issue is I have been looking and whan you want to do anything technical, the internet is useless.
    I can not find any circuit diagrams, or any specs on controllers, even signal mutipliers and doublers that I can build, or purchase and attach to a low cost function generator.

    ------------------------------------------------------

    My target frequency is 1420 MHz.
    Now I can buy a 50 dollar signal generator and output a sin wave of 177.5 MHz.
    And then I want to multiply the signal by 8 (2x2x2), to achieve a sine wave signal of 1420 MHz.
    Then I can just use a non-inverting Op-Amp to convert that into a square wave.

    ------------------------------------------------------

    If anyone can help direct me into the correct components and/or circuits, maybe even a low cost device that can already do this, I would greatly appreciate it.
    Or if there is a simpler way to achieve this task, it would be nice.

    I have tried looking for crystals and oscillators, but I can't find anything relevant to achieve my task.

    Thank you for your help. I am hoping for as high as possible of a duty cycle. I am ultimately trying to get a 0v to 5v pulsing DC signal at 1420 MHz.
    From there I will play with it.


    EDIT:
    Ultimately I am trying to generate a plain RF signal of 1420 MHz. I am not doing anything high power, Just a low power range of around 5-10 feet...
     
    Last edited: Dec 2, 2012
  2. BobK

    BobK

    7,682
    1,686
    Jan 5, 2010
    Not sure how you get 1420MHz from a 0-1GHz signal generator. (1000MHz = 1GHz)

    Do you realize that these frequencies are way too high for microcontrollers? Do you realize that things operating at this high a frequrencies are not cheap? If you can find something for $400, buy it!

    Bob
     
  3. davenn

    davenn Moderator

    13,709
    1,909
    Sep 5, 2009
    There are pleanty of VCO options that cover the 1420MHz freq you require
    have a look at the Mini Circuits site they have VCO's that generate the signal at the required freq without the need for multiplier chains. tho its likely to be a sine wave

    why do you want a square wave ?, its going to be a VERY DIRTY signal rich in harmonics all over the spectrum with the possibility of upsetting other users

    cheers
    Dave
     
  4. BlairH

    BlairH

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    Dec 3, 2012
    I was going to suggest a CD4060, but then I read the 1420 MHz part. That's going to be real tricky getting something that high.

    Blair
     
  5. GHOSTOWLGRID

    GHOSTOWLGRID

    12
    0
    Dec 2, 2012
    Sorry, I wasn't thinking, I am currently working on another project that requires a square wave and accidentally mixed the 2.

    I want to try to output a clean sin wave signal of (no specific amplitude, something proportional) at 1420 MHz.
    I have a grounded out lab setup to contain the signals so that they do not cause any problems for the outside world.

    My issue is I found a basic AM transmitter circuit, and also a basic FM transmitter circuit, both of which I built and tested. But I can't seem to find a circuit that can transmit this frequency for me.
    Just the plain frequency itself. Nothing in it, no messages...

    I was wondering if anyone knew of a way I could do this. I was looking into timers and oscillators, but I can't seem to find anything that I can use to output this signal effectively.

    I can send a signal through a wire, but I can't seem to transmit a signal. It just doesn't want to work for me.

    ---------------------------

    I would rather try and build a small circuit than have to connect up to a signal generator, multiply a starter signal to my target signal, and then try to transmit it.
    I'd rather just try to generate and transmit...

    EDIT:
    I was looking into the 555 Timer chip, but it does not seem to be able to run a circuit to output anything "high speed."
    But even if it did, It would be a signal in a wire, I would then have to transmit it, which I don't know how to do that good...
     
    Last edited: Dec 3, 2012
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
    2,807
    Jan 21, 2010
    If you try to transmit using a square wave, you will be hunted down (and I'm sure some people would like to add "and shot").
     
  7. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    To think that it is easy to deal with these very high frequencies is delusional.
    The 555 can deal with perhaps 1MHz, CMOS 5Mhz and ECL over 100MHz but to get up to 1000MHz very special techniques are required. It is impossible to wire up a test circuit because of the stray inductances and capacitances. Even the active devices need to be characterised for their termination impedances. Printed circuit board tracks become transmission lines and need accurate manufacture.

    High frequency synthesis seems to be advancing at a great rate and prices are dropping but it is not my area.

    Your 'grounded out' lab setup will not contain these signals unless it is completely surrounded with a fine metal mesh making a Faraday cage. A microwave oven can be seen to have proper screening.
     
    KrisBlueNZ likes this.
  8. GHOSTOWLGRID

    GHOSTOWLGRID

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    Dec 2, 2012
    Well, idk.

    I Have a grounded screen mesh like from a microwave, but different, I was given it to use.

    I have been trying to build a frequency output using the NE555 timer, but so far I have been having issues trying to calculate the output frequency given the components...

    I figure I can try to build it with that first before buying anything else as I already have a pack of them and other miscellaneous resistors and capacitors...

    ------------------------------

    If I output a frequency in Hz at a high enough power into a wire, that will cause radio waves to emit? Or do I have to actually build a transmitter, or is that my transmitter?

    My issue is I can work with circuits, but when it comes to signals going wireless, I'm lost.
     
  9. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    The wavelength of a signal is 300/f(MHz), so if you get your 555 reved up to 1MHz, then you will have a wavelength of 300m.

    For an aerial, a halfwave dipole consisting of a wire 150m long, fed in the middle would do the job.

    If you play with 1000MHz, the wavelength will be 300mm and any piece of wire 10mm or so will transmit and receive a significant amount of energy giving plenty of opportunity to go into spurious oscillation.
     
  10. GHOSTOWLGRID

    GHOSTOWLGRID

    12
    0
    Dec 2, 2012
    wow, sounds easier than I thought.
    So if I go about 1 GHz, then a 10mm long wire would do the trick?

    I will be running my signal into TIP147 NPN Transistors, and I will boost the power with that.
    Hopefully It works!

    PS: At this current time I was not given an oscilloscope to use, so I'm stuck guessing my signal output, I found a way to calculate my supossed signal for the 555 timer, but I'm not sure if any of that is correct. Time will tell.

    I will try to output 2.4 GHz, maybe if it works it will disrupt my computers wifi signal. lol
     
  11. davenn

    davenn Moderator

    13,709
    1,909
    Sep 5, 2009
    I gave you the answer for generating the required freq

    Have you looked at the Mini Circuits site yet ??
    they have exactly what you want to get 1420MHz

    Dave

    a TIP147 isnt going to work at 1420MHz you need a proper RF transistor
    Also you dont wanna be generating any more than ~ 10dBm (10mW) else you are going to cause problems to all sorts of other services that are leagally using those freqs. As Steve said you will be hunted down!!

    MOST of the mini circuits VCO's will generate ~ 10mW anyway without the need for external amplification

    Dave
     
  12. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    I suggest that you start with switching leds on and off, then make some audio amplifiers. When you have experience in this area, try to make a radio receiver.

    The TIP147 is a PNP Darlington transistor. It may be possible to get this to work at 200kHz.

    I have a feeling that you are taking the micky and will leave you to press on with your experiments.
     
  13. GHOSTOWLGRID

    GHOSTOWLGRID

    12
    0
    Dec 2, 2012
    Eh.

    I've been looking. I've been having issues finding things and what not.

    Thanks for the refrences and help everyone.

    ---------------------

    I wasn't intending to output anything elaborate. I was only trying to be able to output a 1420 MHz signal about 3-4 inches if that.

    Doesn't the law allow people to have limited use of a frequency as long as it is below a certain power level?
    My 12 volt FM transmitter for my car only goes about 25 feet. I doubt a 5-9 volt signal from a 555 timer chip would go any further. lol
     
  14. davenn

    davenn Moderator

    13,709
    1,909
    Sep 5, 2009
    no it doesnt

    A 555 isnt going to give you freq over a few dozen kHz, so you can forget about 100MHZ and above it aint gonna happen
    there are specific frequencies that have been set aside for experimentation
    and misc. use like garage door openers, A/V senders for around home, cordless phones etc

    eg 433MHz, 2400MHz, 5800MHz

    the freq you have chosen is not in one of those areas. granted .... if your power is VERY low like the 10mW from one of those VCO's then you are not likely to cause any problems BUT put a power amplifier and a decent antenna on it and then you are likely to cause problems

    here is just 1 of some 59 VCO's listed on the Mini Circuits site
    http://www.minicircuits.com/MCLStore/ModelInfoDisplay?13545707955380.9910240385775708

    it covers the range from1370 to 2000 MHz so with the appropriate tuning voltage you can get you 1420MHz.....
    WHY are you obsessed with that particular freq ?

    Dave
     
  15. GHOSTOWLGRID

    GHOSTOWLGRID

    12
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    Dec 2, 2012
    Its the resonant frequency of hydrogen, if my research is correct.
    Anyways I believe this is the frequency this old guy used.

    I picked this project because I stumbled upon some old cancer research guy who used this frequency to set fire to salt water with him RF generator machine thing.
    It also lights up florescent light tubes when they get close to it.

    I want to do the same! :D


    I read and re-read the thread several times already, and I stumbled upon a 2 GHz signal capable chip thing. I will see if/where I can get a hold of one, and then I will see if I can use it.

    If worst comes to worst I will just take a 60 Hz A/C signal and then put it through some analog components and then change it up to 1420 MHz. Which I rather not, I just want to make it fresh and clean without any distortions.


    Thats why I'm all over this. I have to do the rest of the work on my now now, I believe I found all I need at this time.
    Thanks to everyone for all your help! :)
     
  16. davenn

    davenn Moderator

    13,709
    1,909
    Sep 5, 2009
    have fun and dont forget to report back and tell us all how your experiment went :)

    or at least to ask another question or 2 ;)

    Dave
     
  17. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
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    Jan 21, 2010
    Didn't you realise Dave, it's the secret cancer cure frequency that the pharmaceutical companies don't allow us to mention.

    I may have to remove this message, because you know they control all publication of this...

    Also the government is in on the conspiracy and they put this frequency right where you can't legally use it!
     
  18. BobK

    BobK

    7,682
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    Jan 5, 2010
    Steve,

    Shhhhh.. You are putting us all in danger!

    Bob
     
  19. GHOSTOWLGRID

    GHOSTOWLGRID

    12
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    Dec 2, 2012
    LOL

    ---------------------

    So I finally found DigiKey, I totally forgot they existed. I found this:

    http://www.digikey.com.au/scripts/d...ewproducts=0&ptm=0&fid=0&quantity=0&PV344=189

    What do you think of this little guy? Voltage controlled oscillator I believe it is.
    I should be able to just get a variable resistor and then tune it to the right voltage to get the right frequency? :D

    ------------------------------

    I also found this nifty toy:
    http://www.digikey.com/product-highlights/us/en/cypress-semiconductor-cy22800/455

    Only problem is they do not know the output frequency range of it.
    So they will get back to me on that one.

    --------------------------

    Either way I'm thinking of just sticking with the voltage controlled oscillator. Sounds easier and more reliable.


    EDIT:
    I totally didn't realize what VCO meant until I found the oscillator, so when you above was like read what I said boi, I was like I don't get it lol.
     
    Last edited: Dec 4, 2012
  20. Harald Kapp

    Harald Kapp Moderator Moderator

    10,765
    2,424
    Nov 17, 2011
    I'd bet you won't see anything at the output of a TIP147.
    First: The TIP147 is an PNP Epitaxial Silicon Darlington Transistor, not NPN.
    Second: The TIP147 is a Darlington transistor meant to have high gain, but not a high transit frequency. The rise time is 0.5µs, the fall time is 2.5µs. This means a full cycle takes at least 3µs. This is equivalent to 0.3Mhz - way off your design goal.

    You need to look into radio designs, use HF-transistors and very careful placement and layout to make an amplifier operate stable at that frequency.

    What do you need that frequency for, anyway? If we know the application, we might be able to suggest an alternative solution.
     
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