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Discussion in 'Electronic Projects Design/Ideas/Reviews' started by Abeer_engjbr, Feb 10, 2008.

  1. blueroomelectronics

    blueroomelectronics Well-Known Member

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    Capitalization is not a matter of like or dislike, it's simply proper English. Taking the time and effort to make your posts look professional is a reflection of the effort you would expect to get in return.
    You don't submit your reports without due care, do the members here not deserve the same courtesy?
     
  2. Abeer_engjbr

    Abeer_engjbr New Member

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    Blueroomelectronics

    I am sorry, I will take care of my replyes from now on.
    Thank you for your time.

    Abeer_engjbr
     
  3. blueroomelectronics

    blueroomelectronics Well-Known Member

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  4. dave

    Dave New Member

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  5. Abeer_engjbr

    Abeer_engjbr New Member

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    Thank you, you have been so helpful.
    Do you know any research websites except Google and Yahoo.
     
  6. Hero999

    Hero999 Banned

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    Ask.com
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  7. Abeer_engjbr

    Abeer_engjbr New Member

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    Hi Kmoffet,

    I want to know what is the purpose of 555 timer in the ir repeater circuit, how exactly does it work, I've tried to read the link that bluelectronic wrote but am so confussed, especially when i read the Datasheet.
    Thank you.
     
  8. blueroomelectronics

    blueroomelectronics Well-Known Member

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  9. Abeer_engjbr

    Abeer_engjbr New Member

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    I understood the purpose of TSOP1738, and why we use the 555 timer, but, on the other hand i still can't get what equations i must use in order to get specific frequancy ( 38 kHz for instant).
    I've read the datasheet of LM555, and there is many functions for it, I can't figure out what is the name of it in the ir repeater circuit in order to know what equations i must use to determine C and R values to get a certain frequancy , how 555 is reset by the collecter of the junction (in the circuit) , and why 5 volt or 12.
    When i asked some engineers about 555 they said that it is a modulation timer, can i build a repeater circuit without it?
    Thank you.
     
  10. blueroomelectronics

    blueroomelectronics Well-Known Member

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  11. Abeer_engjbr

    Abeer_engjbr New Member

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    Hey
    Does that mean that the 555 function or name in the ir repeater circuit is ( Astable 555 square wave ). But realy if that so , I've noticed that it doesn't have the same connections in the circuit as Astable connections ( for examlpe pin 7 in the repeater circuit is not connected between R1 and R2 aas it does in the Astable circuit you show me ( and i saw on the datasheet ).

    Please help me get a clearer idea , I'm so confused right now!!!
     
  12. Abeer_engjbr

    Abeer_engjbr New Member

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    Hi Everyone,
    Miss me? I don't think so! Any way if you don't remember as I'am sure of, I asked about the IR REPEATER circuit, I constructed it and there was a problem, IT DID NOT WORK! any way i still have plenty of time to try make it work but here's what i did:
    1) You have advised me to use 9 Volt instead of the voltage regulator in the output part, and that's what I did. But realy i think it's more conveniant to put a regulator.(I'll try it tomorrow) .

    2) In the LM555 connection, it is obviously connected as Astable circuit, but what must I put in the DIS pin, as it is not connected to anything, and as far as I know I connect it to a capacitor (1 n) with the grounded .(is it right?).

    3) What is the function of the capacitor that is connected before the Voltage Regulator, and the capacitor between Vcc and GRD in 555 IC?

    4) I've placed an oscliscope on the 2 K:eek:hm: that is connected to the OUT of 555, and nothing happened on the screen after I pointed the IR signal to the input Photodiode, and the Led did not flash.( for these resones I asumed that it did not work! is that so?)

    Thank you all, I Hope To Hear From You Soon.
    The Link You Gave Me Is:http://english.cxem.net/infrared/ir7.php:)
     
  13. Abeer_engjbr

    Abeer_engjbr New Member

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  14. KMoffett

    KMoffett Well-Known Member

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    Either way, but the 12v will provide a slightly higher output on the LEDs.

    DIS should be connected to the junction of R4 and PR1. Won't work otherwise.

    These are to filter out possible noise on the +12v ...but...if you are going to use the regulator change C4 to 0.1UF and add another 0.1uF capacitor on the 15v side of the regulator, between the IN and COM terminals. Both of these caps should be as close as physically possible to the regulator pins.

    Because the 555 was not working. I also notice is the second schematic the 555 circuit id different, and didn't see an explanation.

    Ken

    And your smiley face got in you URL link.
     
  15. Abeer_engjbr

    Abeer_engjbr New Member

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  16. Abeer_engjbr

    Abeer_engjbr New Member

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    :) or must I be :(
     
  17. audioguru

    audioguru Well-Known Member Most Helpful Member

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    DO NOT connect the DIS pin of the 555 to anything. The OUT pin is part of the oscillator in this circuit instead of the DIS pin.
     
  18. Abeer_engjbr

    Abeer_engjbr New Member

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    Realy? But is the first circuit correct or the second ( must i use 2 resistors to the 555 as the first circuit (R4 and PRE1), or just 15 as the second circuit?)
     
  19. Abeer_engjbr

    Abeer_engjbr New Member

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    What do you mean by (It's part of the oscillator)?
     
  20. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Other 555 oscillators have the DIS pin operating the oscillator.
    This oscillator is different.
    The resistor R4 from the OUT pin charges and discharges the C2 timing capacitor that is connected to the TRG and THR pins.
    The DIS pin in this oscillator is not connected to anything.
     
  21. Abeer_engjbr

    Abeer_engjbr New Member

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    Thank You!
    I'll connect again it tomorrow and see the results.
    If you read what in the reply before you, is the rest true?
     

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