how the calculations come about in the circuit.

Discussion in 'General Electronics Chat' started by lostdort, Apr 10, 2010.

  1. lostdort

    Thread Starter New Member

    Apr 10, 2010
    i saw this pest repeller circuit, to be able to produce up to 80kHz.
    but i do not know how the calculations is done. could any1 be kind to help me understand the flow & calculations on this circuit?
    the circuit is as attached.

    is there anway to increase the frequency from 80kHz to 1MHz?
    if so, how can it be done?
  2. Wendy


    Mar 24, 2008
    Yes, and No. The electronics can do it, but that speaker will be doing good to produce 80Khz. I have seen 1Mhz ultrasonics, but it requires some very special transducers (speakers).
    lostdort likes this.
  3. hgmjr

    Retired Moderator

    Jan 28, 2005
    I agree with those who have stated that it is very unlikely that you will be able to modify this circuit to produce an output from the piezo-speaker that is much above the existing frequency of 30KHz to 40KHz.

    lostdort likes this.
  4. Jazz Bass Special

    New Member

    Apr 9, 2010
    Look up the 555 IC datsheet.
    That is what is producing the frequency.
    There is a note at the bottom of the print telling whick resistors change the frequency.
    lostdort likes this.
  5. redlight000


    Feb 26, 2010
    Hi Lostdort,

    Hey I've got that diagram, so in the epe mag... & I tell you its a good circuit.. I dabbled in this a few years ago!! anyhow.. 1st what pests are you trying to repel? eg. Cats.. I think of the top of my memory, they get annoyed at around 60khz to around I spose to 80khz <wait though depends on the cat/dog age... so you could be directing your device at the pest and its stone deaf!!! thought of that Yes"Trial & error" here..

    I have not buit that but other kit I bought which was audible, then goes up to the dog/cats hearing range... I read the write up on you diagram that device.. & it said if you change c3 to 100nf your hear the Tone yourself!! and apprently its Loud.. but dont forget.. change the o/p from the Transducer your using to a Piezo horn, there very good
    I find the Ultrasonic 40khz if not done right are flipping hopeless!! thats my opinion..

    Right the specs of the P/horn is
    FReq range 4khz to 40khz
    Power 150Wmax/ 75Wrms
    impedence 250-50 ohms...
    and all the diameters.. you can get recessed horn or protruding horn!!<< if I've got that right.. there made in cHina..
    and like bill said very effecient...
    I dont know about ultrasonic transducers they bore me... and quite hard to drive..
    well I personally think so...
    IF you want a really good repeller then email me.. its ready made.. 130db.. sound pressure..
    !!!! juicy a?
    But one thing I dont get you on is Why do you want to go as high as 1meghz?? the pests as I see it wont hear it but proberly feel it more.. ok
    lostdort likes this.
  6. redlight000


    Feb 26, 2010
    Hi again, lostdort,

    here's a few frequencies..
    rigg up a 555 in Astable mode. ok R1 =4.7k
    R2 = 10k
    thats R1+R2 is the resisitor bit..
    now for the C/value.. you can put in
    eg example
    10uf electrolitic cap =5.8hz
    1uf electro = 58hz
    100nf <nano farads normal cap =580hz
    10nf ^^^^^^same = 5.8khz
    1nf ^^^^ =58khz... so you have to work out the exact or around abouts the caps bit.. yes its maths.. thats taken me a while to do But I got there its 50/50 with this game..
    anyhow so you got 58khz.. now go lower picofarads.. then your going up in Freq) got it.. Just dabble a freq counter is handy because you getting a proper reading near as damm it..
    Ive got a basic freq/counter thats from 5hz to 10mhz...
    that suits me.. all this may NOT apply to you but its the maths involved.. ie if you want to design a circuit of your own like Ive done.. & Yes its Not easy grrrrr..
    hope this is of use... if not ..
    leave it.
    lostdort likes this.
  7. atferrari

    AAC Fanatic!

    Jan 6, 2004
    Nonsense. The OP is asking to stretch it up to 1 MHz.
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  8. Ron H

    AAC Fanatic!

    Apr 14, 2005
    That's wrong. The CA3130 and the R's and C around it determine the frequency.
    lostdort likes this.
  9. lostdort

    Thread Starter New Member

    Apr 10, 2010
    wat will the effect be? will the frequency be strong enough to actually move/blow the pest away?
  10. retched

    AAC Fanatic!

    Dec 5, 2009
    Why not just use a fan?