CMOS beginner question

Discussion in 'General Electronics Chat' started by mbohuntr, Oct 25, 2010.

  1. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
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    32
    I am still working on the 555 camera trigger project when time permits, and have found circuit too power hungry for batteries using LM555's or 556. (9mA and rising) Sooo... I am going to break open the CMOS 555's. I have not practiced ESD prevention before, so if I am working on a wooden computer desk, and I ground myself (continuously) with a homemade strap and a 1M resistor, will this offer enough protection?? I am building the complete circuit on a breadboard first to trouble shoot it. Any advice would be appreciated. Thanks. Mike
     
  2. creakndale

    Active Member

    Mar 13, 2009
    68
    7
    For the hobbyist, a wooden bench top is one of the better materials to have (more neutral as positive/negative charges go). Always use the ground strap with 1M resistor as you've mentioned. Wear cotton clothes. Keep the humidity high (A forced air heater can really lower humidity levels in the winter).

    Some good info here:
    http://www.esda.org/documents/FundamentalsPart1.pdf

    creakndale
     
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  3. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    I wrote an article for the ebook on the subject.

    ElectroStatic Discharge

    In general don't go overboard. Some stuff is more sensitive than others. If you live in an environment where sparks fly occasionally this is a clue (bone dry environments, such as Phoenix, Arizona). Many times I don't worry about it for my home projects.

    Refresh me as to where your project is, I'll see if I can make it squeak on the current draw.
     
  4. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
    413
    32
    Thanks Bill, I will rebuild the circuit using 555cn's. I am using a PIR as a trigger to begin the first stage 1/2 sec. pulse, triggering the wake up pulse to the camera, and changing the state of the JK flip flop. This shunts a RC circuit to delay the second stage trigger for about 1 second. Then the second stage 555 pulse triggers the shutter as well as resets the jk flip flop. The clock pulse for the JK is a colpitts oscillator with a second npn transistor to clean up the square wave.

    Right now the oscillator is working well, as is the first stage to the flip flop. Starting to feel like a "mousetrap" game. pretty complicated for a second project...;)
     
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