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coding using pic 16f877a with tsop4p38(proximity sensor)

Discussion in 'Microcontrollers' started by ripingz, Feb 18, 2012.

  1. ripingz

    ripingz New Member

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    i want to make regulated 5V produced by a 12V battery..... but as i know..im afraid the output regulated voltage is not accurately get 5v ....it must be around 4.5v to 4.8v.... so it must affect the frequency of the infrared.....how about this....
     
  2. ripingz

    ripingz New Member

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    i just saw my pcb circuit... as i can see....after the +voltage source.... i connected to 2k resistor...and then serial it with 12k !!! is this the problem???
     
  3. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    @post#61
    On what basis do you conclude that a regulated 5V supply will be only 4.5V?

    @post#62
    Please present a schematic. Both resistors, in fact all of your resistors and everything else in the circuit, are after the supply. It depends on where they are connected. Was it connected as you showed in the post on page 6 of this thread? As mentioned there, that is the wrong place for it.

    Let's settle first of the voltage you will be using.

    One other thing, are you using decoupling capacitors across each 555's supply? If not, use a 0.1 uF ceramic capacitor between the V+ pin and Ground pin of each 555 and as close to the V+ pin as practical. Power supply problems can plague these designs. Your instructor has probably already told you about it.

    John
     
    Last edited: Apr 4, 2012
  4. dave

    Dave New Member

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  5. ripingz

    ripingz New Member

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    1) i had an power supply circuit... im using 12v 7.6ampere battery...the output gets around 4.5v-4.8v... not accurately 5v

    2) View attachment 62972

    3) i do the connection as in the schematic...
     
  6. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    Please present your current schematic so we can have a common reference point. That schematic in post#64 will not work. That has already been established.

    John
     
  7. ripingz

    ripingz New Member

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    my current circuit builded is based on this...i'm using 6v batt....and it get around 7khz of frequency at the ir...what's wrong with this circuit....what i have to change.....if i intend to use the input voltage that is regulated by power supply circuit...
    this is my power supply circuit i had used on my mcu...but i had not implement this circuit into the transmitter View attachment 62973
     
  8. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    You appear to have a direct short between your positive supply (battery) and ground. I am surprised you even get 7 KHz from the oscillator.

    Please:
    1) Be more careful in the schematics you present. Neither of the last two you have presented will work. The one in post #64 has no power going directly to pin 8 (Vcc) of either chip. What you may be seeing is the result of driving the chip from a pin that is not intended for that purpose. The schematic presented in post#66 has a direct short. Did you intend to add a capacitor instead on the input?

    2) Please include full part numbers as relevant. For the '555 that you are using, please confirm it is in fact the NE555. For the voltage regulator, are you using a 7805 with no prefix or some other version of a similar 5-V regulator? What is the current rating for your voltage regulator?

    John
     
  9. ripingz

    ripingz New Member

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    1)sorry my bad...i gave the wrong schemtic...this is wat i have done to my circuit....the wrong schematic circuit is the long time ago error which i had mention long time ago that i got no output at all... an this is the real schematic which i had implant to my circuit View attachment 62988

    2) im not using ne555. but im using the other model HA17555. sorry for my bad too...and this is the real power supply circuit... View attachment 62984 yeh...for the voltage regulator..im using the lm7805.. i tested it today.... the ACV on the multimer is 10A and the dc voltage i get is around 4.2v..I dont know why the voltage begin more drop than last time.... but the battery is weak already from 12v to 10v.....
     
    Last edited: Apr 4, 2012
  10. ripingz

    ripingz New Member

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    :eek::p:p:p:p
     
    Last edited: Apr 4, 2012
  11. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    1) For your supply, I usually use a capacitor on the input too; although, that is not "required" in all cases (See: datasheet).

    2) Re:
    I have no idea what you mean.

    3) Recharge your battery.

    4) How did you measure the frequency that you report? Let's try this: Disconnect the wire from pin4 of U2 and connect pin 4 directly to pin8 of U2. Then measure the frequency you get at pin3 of U2. Measure the voltage at pin8 of U2 to ground.

    5) Second, measure the frequency at the wire you disconnected (that is, the frequency at pin 3 of U1). Leave the wire connected to R6.

    6) Be sure to have those decoupling capacitors I mentioned installed.

    John
     
  12. ripingz

    ripingz New Member

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    ok.....i will then try to this experiment by using breadboard....but then....how about the time length of 'off' time and 'on' observations....do i need these experiment....?? if so..what should i do
     
  13. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    If you are using an oscilloscope, that should be obvious. Duty cycle is important to consider for both oscillators, but not nearly as important as getting the frequencies right.

    John
     
  14. ripingz

    ripingz New Member

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    i will keep in touch in this forum...showing the progress.....thx for teaching me all above...thx alot
     
  15. ripingz

    ripingz New Member

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    this the the power supply u asked me to coupling....and i get around 5.05 volt....using the simulation..here the result... View attachment 63088
    and this the transmitter circuit... View attachment 63089 ..
    based on the schematic..i want to ask your help...is there any connection error here....or do i need more modification.... i got to present in 1 week !! it's makes me feel bad...i cant simulate it...because the cpu is overload...but when i adjusted the resistor r7 to 1k...i can saw the blinking of the ir ....hope u can reply this very soon.
     
  16. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    Your attachments don't load.

    John
     
  17. ripingz

    ripingz New Member

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    this the the power supply u asked me to coupling....and i get around 5.05 volt....using the simulation..here the result... View attachment 63108
    and this the transmitter circuit... View attachment 63107
    based on the schematic..i want to ask your help...is there any connection error here....or do i need more modification.... i got to present in 1 week !! it's makes me feel bad...i cant simulate it...because the cpu is overload...but when i adjusted the resistor r7 to 1k...i can saw the blinking of the ir ....hope u can reply this very soon.
     
  18. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    That schematic is nothing like what we have been talking about and will not work.

    Who gave it to you?

    Why don't you return to what was almost working and make it work?

    Since your presentation is in about one week, surely you must be interested in efficiency instead of launching off in a completely new direction. Hint, Vcc and ground to a 555 should not be supplied through a capacitor. I mentioned "decoupling" capacitors. Did you misunderstand, and is that what you are attempting to do? The decoupling capacitor goes between Vcc and ground, not between Vcc and the supply. I suggest you look up and read about decoupling capacitors. They are even described in the 555 datasheet, I believe.

    John
     
  19. ripingz

    ripingz New Member

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    i'm doing it all by myself....sorry for the mistake..yes i've done a mistake....so the capacitor that i added to the vcc of the timer.....is wrong right.....and the capacitor should be put at the power supply (+) and negative supply...??? is that it.......and how about the ground pin of the timer....i had put the capacitor at there....is this ok? View attachment 63130

    about the power supply....is it ok?
     
    Last edited: Apr 7, 2012
  20. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    The power supply looks okay, with the reservation mentioned above about using an input capacitor.

    You still have capacitors from the 555 ground pins to ground. Thus, there is no proper DC current path. Here is a link on decoupling. The part you are most interested in begins about page 6: http://www.electro-tech-online.com/custompdfs/2012/04/MT-101.pdf

    Have you done what I suggested above to determine the frequency of your oscillators and adjust them as necessary?

    John
     
  21. ripingz

    ripingz New Member

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    is this correct connection for the transmitter.....??? View attachment 63132 ..... i have not experimenting the frequency produce with this circuit...as the lab is closed and open due to the time class.....and calculating the frequency using proteus i dont know how....thats why im in gamble now :p
     

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