Proof Reading LEDs, 555s, Flashers, and Light Chasers

Discussion in 'Feedback and Suggestions' started by Wendy, Apr 30, 2009.

  1. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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  2. bertus

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    Apr 5, 2008
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    Hello Bill,

    Is there no need for a current limiting resistor in figure 10 of page 5 in PWM generator #1?

    [​IMG]


    In the simple pwm of SgtWookie with the 4093 there is one.

    [​IMG]

    Greetings,
    Bertus
     
  3. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    I'll be building a test circuit, but I don't believe there is, no more than there is a need in this schematic...

    [​IMG]

    which as been verified.

    See 555 Hysteretic Oscillator.
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello Bill,

    Here I have changed your picture with what I mean.

    [​IMG]

    The extra 100 Ohm resistor is to protect the potentiometer and 555 against high current pulses.

    Greetings,
    Bertus
     
  5. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    I understood, but the current between the Hysteritic Oscillator and the PWM Oscillator is vertually identical, capacitor and all. I really do not feel it is necessary. With the Hysteritic Oscillator there was no heat at minimum setting, none what so ever, and the frequency went well into the ultrasonic with a 10µF capacitor.
     
  6. Wendy

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    Hehe, I have to admit you were right about the need for a resistor, though for a slow flasher it isn't as necessary as in some schematics (because the pot will be on the high side, always). Basically when I tried a fresh battery the 555 got hot. Didn't blow out though.

    But that's not the reason for this post.

    Basically I'm running out of room to modify the article. I'll be able to do what I want this time, with some minor concessions, so this isn't a problem this time.

    So far I've had two separate threads, the second was started because of the same problem with the first that I'm having now. I want to add chapters, and keep them contiguous. I may have to start a 3rd thread, but that isn't my prefered solution.

    Blogs would work except they don't allow attachments. Thinking about it, I could still make this work, as a separate blog per chapter, with an index blog linking all of them together. Hmmm.... That could work.

    Threads can be written to by other people, which means it can't be edited indefinately since I can't add more chapters in front of their comments.
     
  7. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    I have added a new chapter, and inserted it into chapter 3.

    The LED / Resistor Only Bargraph

    Plese check it out and let me know what you think. I haven't put it on the blog yet, I'll let it sit for a little while.
     
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