4011 NAND gate into 1.7 mhz oscillator

Discussion in 'General Electronics Chat' started by rocky3, Apr 29, 2008.

  1. rocky3

    Thread Starter New Member

    Apr 28, 2008
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    Hi, I'm the obsessive ultrasonic transducer questioner. How would you go about making an oscillator out of the 4011 to drive a peizo transducer?I found a circuit in an electronics book that uses a crystal, but it doesn't seem to want to oscillate.
     
  2. Caveman

    Active Member

    Apr 15, 2008
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    This is for the fogger, right? Aren't you trying to drive out quite a bit of energy here? You probably need something with a little more power output. Otherwise, do you know much about this transducers electrical model?
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    Piezo devices are generally made with quartz crystals. These crystals are actually quite fragile as they are extremely thin, and can be easily broken if subjected to rough handling (dropped).

    If you connected the transducer directly across the 4011 without snubber caps (perhaps 30pF-70pF), it's likely that if the transducer is good, that it destroyed the 4011 with a reverse HV spike right after power was applied, or even with power off if you tapped on the transducer. Piezo transducers can generate very high voltage spikes just by being mechanically stimulated by light taps or audio inputs. They are very low in current, but the voltage is sufficient to kill CMOS devices by punching holes in the gates.
     
  4. hgmjr

    Moderator

    Jan 28, 2005
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    Can you post a sketch of your circuit? It would be helful for us to see how you organized your design. A sketch would shed light on your power supply and the overall signal flow.

    hgmjr
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
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    Is this for an ultrasonic fogger? I thought those frequencies were in the 25 - 40 KHz range. My old ultrasonic cleaner ran in that range.
     
  6. Caveman

    Active Member

    Apr 15, 2008
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    There was a thread yesterday that I looked up a bunch of stuff for an ultrasonic fogger. Most of the transducers are 1.7MHz. Technically, this is ultrasonic as well.
     
  7. rocky3

    Thread Starter New Member

    Apr 28, 2008
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    The circuit that I am trying is actually from an electronics book. It's not mydesign.[​IMG]
     
  8. SgtWookie

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    Jul 17, 2007
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    You're not trying to build this circuit on a breadboard, are you?

    A breadboard will have too much capacitance.

    You need to wire it up on perfboard.
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    Give the attached circuit a try.

    Basically, it's an adaptation of a crystal oscillator circuit from TI's CD4045B datasheet. You really should only need one of the 4011's gates to get it going; the 2nd gate is simply an optional driver circuit.

    The values of R may need to be increased. Crystals don't simulate well in the sim I'm using.
     
  10. rocky3

    Thread Starter New Member

    Apr 28, 2008
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    Thanks, I'll give this circuit a try. I need to get a 1mhz crystal first. That software is cool. Is it freeware?
     
  11. SgtWookie

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    Jul 17, 2007
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    Circuitmaker is no longer supported by the company who wrote it. Circuitmaker Student used to be downloadable for free from the Circuitmaker website. You can still find it, but you have to search. It's pretty limited in what you can do with it, because you can't add components to the library, the existing library is missing any component that was developed within the last 10 years, and you can't have more than 50 components in any one simulation.

    Their newer product, Altium Designer, doesn't have a demonstration version, and is terribly expensive.

    I just use it for "quick and dirty" simulations, because I got used to using it.

    Linear Technology's LTSpice/SwitcherCad III is a much better SPICE simulator, and is a free download from their website. One drawback is that I have yet to find libraries of TTL and CMOS logic ICs to use with it; I don't have the time to create them.

    TINA seems to be somewhat popular. There is a freeware version available on Texas Instrument's website called Tina-TI. A bit of rooting around in their design tools menus will get you to it.
     
  12. smokey

    New Member

    Jul 28, 2008
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    I am interested in the comment about building these on a breadboard. it that really the case cause I just try to prototype one on C4060 with a 44Mhz Xtal but getting nowhere.
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    That's correct - you can't breadboard a crystal oscillator circuit. There is simply too much capacitance in the breadboard itself.
     
  14. bertus

    Administrator

    Apr 5, 2008
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  15. smokey

    New Member

    Jul 28, 2008
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    Thanks, I eventually get it working on a PCB..
     
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