plz ans quick

Discussion in 'General Electronics Chat' started by fine, Apr 7, 2013.

  1. fine

    Thread Starter New Member

    Apr 7, 2013
    what is the output of a transistor when dc supply provided??? i am actually working on a project n it says that if the button is pressed when oscillaor is low the capacitor C2 will discharge. what i dont get is y would the oscillator be low since v r giving it the same supply all the time. so i thought may be it had something to do with the transistor Q1
  2. MrChips


    Oct 2, 2009
    Geesh! I guess you are not willing to listen and learn and you don't care.
    DerStrom8 likes this.
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    Ok its an oscillator, so its varying between pos and neg at the speed of its set frequency, so it will be be either high or low at the time you press the button. So if its high it charges the capacitor if its low it discharges. Simples!
    Last edited: Apr 7, 2013
  4. fine

    Thread Starter New Member

    Apr 7, 2013
    Y uz C2 I mean the base of Q1 is connected to the gate directly right so y do v need a capacitor to provide it energy? Is it so that the capacitor can provide Q1 energy fairly regularly since there will be a pause between energy from gate n I think this fluctuation can may be harm The transistor
  5. ke5nnt

    Active Member

    Mar 1, 2009
    Online Dictionary
    When you use text speak, something cute and fluffy dies
    shortbus and elec_mech like this.
  6. Dodgydave

    Distinguished Member

    Jun 22, 2012
    If you cant speak English , a translator can be supplied for you!

    In it bruv!
  7. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    A) the title start with something that looks like "please answer". Ok, my answer is 42.
    B) the title ends with "quick". Many forum members are asleep as this is an international forum. That is if they even get past the generic (and somewhat rude and demanding), "plz ans).
    C) this is an English forum. Text speak is not English.

    Where is that thread discussing annoying posts? Perhaps it should be a sticky. :D
  8. MrChips


    Oct 2, 2009
    Sure. Here is what I posted when AG was leaving:

    Say, with AG gone, someone has to take up the slack and start being rude to senseless, lazy and selfish posters who need to be told how to make a proper post.

    Here are my new rules:

    1) The subject title must state the problem. "Need help" does not do it.

    2) Never ask for help ASAP, or urgently. This will delay responses by 7 days, at least.

    3) The first post of the thread must describe the nature of the problem completely in no fewer than 50 words.

    4) All posts must use proper grammar, punctuation, capitalization. No texting is allowed.

    5) All acronyms must be spelled out unless it is common knowledge in the electronics field, such as BJT, MOSFET, CMOS, TTL, PCB.

    6) No cussing, swearing, flaming, put downs on age, sex, religion, politics or nationality allowed.

    7) A circuit related question must be accompanied by a clear circuit diagram.

    8) The poster must have completed an internet search of the subject matter before posting a question.

    9) Any school, college, university, homework/project/assignment must show efforts to solving the problem.

    10) Don't bother to ask for suggestions on final year projects. We don't have any.

    Anything I missed out?
    Meixner, tobyw, shortbus and 6 others like this.
  9. spinnaker

    AAC Fanatic!

    Oct 29, 2009

    Do not end you sentence with "doubt". Example: "Interfacing Pic to LCD doubt".

    Sorry but I just find that type of sentence strange.

    Better "Problem with interfacing Pic to LCD".


    Post in full complete sentences / thoughts. We can't read your mind. (expanding on your rule #3.
    Include a schematic if your question is about a project you are building.
    Post source code when applicable.
    Post code within code tags when posting code.
    Tell us what YOU did to resolve your issue (troubleshooting, debugging, searching the internet etc). Posting something like "I have to design a robotic device please help" or "there is a problem with my pic code, what is wrong"? Just doesn't cut it.
    Last edited: Apr 7, 2013
  10. WBahn


    Mar 31, 2012
    And if you absolutely MUST use text-speak, at least text-speak in English. This "y do v need" text-speaking in German is double annoying. :D
  11. PackratKing

    Well-Known Member

    Jul 13, 2008
    Amen to that... Acronyms are a major PITA as well, unless used in some semblance of context...

    The other PITA, is not proofreading an offering before hitting the "enter" key...
    Last edited: Apr 8, 2013
  12. Brownout

    Well-Known Member

    Jan 10, 2012
    Why do you think fluctuaion can harm a transistor? That's exactly what transistors are made to do.

    The capacitor is there to ramp up the base voltage over time, rather than the very fast edge that would come directly from the oscillator.
    Last edited: Apr 8, 2013
  13. tobyw


    Mar 21, 2013
    MrChips - hey, good set of rules. But if you have rules on posting questions, it only seems fair to have rules on posting answers too... :p Suggestions...

    1) Read the whole question before answering.

    2) Do rule 1 again.

    3) Answer the actual question(s) rather than treating it as an opportunity for general word association. Ie. if someone asks 'Why is domestic current supplied as ac?' do not respond 'ac means alternating current. Domestic current is usually 50hz. What are you trying to do?'

    4) Do not be the first person to respond if your post starts with the words 'I don't know about this subject but..'

    5) Do not answer a question by suggesting the user tries a different project.

    Do not question the poster's ability to tackle a project. If they are trying to build a remote Mars lander with an arduino, it's their choice. Failure is the best method of learning. If you don't let them fail, they won't learn.

    7) If the poster's project might result in death, jail, or divorce, rule 6 does not apply.

    8) Never suggest that someone asking a question about c isn't ready to be asking those kinds of question until they learn a or b etc. If necessary, a cursory explanation of c with a suggestion about reading up on a and b is fine. But do not refuse to discuss c at all. The greatest minds in science didn't get that way by knowing their place and only asking questions someone else thought they were ready to ask. There's no reason why us dummies shouldn't do the same.

    9) There is no such thing as simple maths. Please don't tell us stuff like 'all you have to do is solve theta where beta is equal to zeta over the square root of alpha to the power of beta divided by three omega plus five bananas'. Tell us the answer, but at least admit that it's hard.

    10) Do not hijack threads to discuss more complex matters with people who can calculate the exact frequency of an LC circuit in their head while fighting a grizzly.

    11) Just because someone is asking a question in an internet forum does not mean they are mentally retarded. They might be - but give them the benefit of the doubt.

    12) Be nice..
    absf and GopherT like this.
  14. GopherT

    AAC Fanatic!

    Nov 23, 2012
    Previous post could make a nice "sticky", eventhough he has voilated his own rule #10 ;).
  15. MrChips


    Oct 2, 2009
    The thing about texting on a forum is they think they are texting to their buddies.
    They don't realize that they are standing up in public and making fools of themselves by attempting to communicate in gibberish.
    DerStrom8 likes this.
  16. Meixner


    Sep 26, 2011
    That gets a thumbs up from me !
    PackratKing likes this.
  17. YokoTsuno


    Jan 1, 2013
    The oscillator output (signal on pin 3 of the NAND gate) is a rectangular wave that pulses between 0 and 9V. Something like this:

    To get the wanted lighting effect you need to convert this to a sort of sawtooth wave, which looks like this: except that in your case the goes from 0-9V and the shape is more like that of a shark’s fin. This sawtooth conversion takes place with what is called an RC circuit. How steep the slope is depends on the value of R3 and C2. The larger R3/C2 the less steep the slope is. The voltage reaches roughly 63% of its maximum value (Here 9V) at a time T=R.C (22000 x 0.00047 = 10,4s)

    Because the author wants the downward slope steeper, a second, much smaller resistor, R4 in combination with a diode is used. The diode works like a non-return valve for liquids: .If the oscillator output is at 0V, the diode "opens" and discharges C2 much faster (470 x 0.00047 = 0.22s). When the oscillator flips to 9V the diode will "close" again.
    absf likes this.
  18. kubeek

    AAC Fanatic!

    Sep 20, 2005
    absf likes this.
  19. absf

    Senior Member

    Dec 29, 2010
    Thank you for posting the site. Part of that circuit looks like the inside of a ICL8038 function generator.

  20. vk6zgo

    Active Member

    Jul 21, 2012
    "10) Do not hijack threads to discuss more complex matters with people who can calculate the exact frequency of an LC circuit in their head while fighting a grizzly."

    Why,oh why,is it,that I can never find a Grizzly when I have to do this?

    They banned me from the Zoo & suggested I get some new batteries for my calculator,instead.:D
    tobyw likes this.