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555 Freq & Duty component calculator — Parallax Forums

555 Freq & Duty component calculator

Spiral_72Spiral_72 Posts: 791
edited 2011-07-22 06:57 in General Discussion
Hey, I thought this was a real good find! Every other 555 calculator I've found works the other way-round.... enter component values and it'll give you F & D.

http://www.daycounter.com/Calculators/NE555-Calculator.phtml

Enter your desired frequency and duty cycle, and p-tooey, it'll give you the components required :)

Comments

  • ElectricAyeElectricAye Posts: 4,561
    edited 2011-07-21 18:27
    That's a nice find. I wonder if it works in real life. The caveat is that the component values might be off by 20%.

    Thanks for sharing this!
  • Spiral_72Spiral_72 Posts: 791
    edited 2011-07-22 06:34
    You are correct, it gives you exact values, which puts you in the ball-park.

    It works!! I built the oscillator last night with the values calculated. I checked the values in my caculator first, and they lined up perfectly.

    I didn't have a 5.061k resistor, but a 4.7k was plenty close enough.


    One more note: The cap value is an input as well. So you can tweak the cap value to offset your resistor values into something a little closer to "Standard" stuff. For example, 50kHz might use a 0.2ohm and 234ohm resistor with a 10uF cap, BUT by changing the cap to 0.001uF, the calculated resistors are more reasonable.


    Enjoy!
  • ElectricAyeElectricAye Posts: 4,561
    edited 2011-07-22 06:57
    Spiral_72 wrote: »
    ...

    It works!! I built the oscillator last night with the values calculated. I checked the values in my caculator first, and they lined up perfectly.

    ...

    Thanks for validating this in hardware. I was looking for a calculator like this last week. I'm glad I procrastinated. Thanks again. :-)
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