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4011 IC

Discussion in 'General Electronics Discussion' started by twister, Jan 11, 2020.

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  1. twister

    twister

    172
    7
    Feb 12, 2012
    This is the timing section of a inverter that I built. The inverter runs a refrigerator. The delay is to allow the pressure in the fridge to bleed off so the compressor will start. The problem is that the IC gate acts as a amplifier instead of a switch, between 6.2V and 6.5V. This causes the inverter to erratically switch on and off for a second or so. Is there a way to make it switch from low to high with no in between? This is on a solar system.

    0111201303.jpg

    [MOD edited - cropped and resized image]
     
    Last edited by a moderator: Jan 11, 2020
  2. HellasTechn

    HellasTechn

    1,524
    212
    Apr 14, 2013
    What voltage and current do you wish to switch on and off ?
     
  3. twister

    twister

    172
    7
    Feb 12, 2012
    The inverter requires +5V. The 15K resistor drops the voltage to 5V.
     
  4. bertus

    bertus Moderator

    752
    268
    Nov 8, 2019
    Hello,

    You can better use an 4093 in stead of the 4011.
    The 4093 has a schmitt-trigger inside, that will have a sharp transition.

    Bertus
     

    Attached Files:

  5. Audioguru

    Audioguru

    2,873
    644
    Sep 24, 2016
    You need a comparator IC (an LM393 is a dual comparator). It can be adjusted to switch at whatever voltage you want.
    you can add "hysteresis" to it so that it switches abruptly and quickly.

    You could also use a Cmos logic inverter or gate with a Schmitt Trigger input but you cannot adjust the switching voltage.
     
  6. AnalogKid

    AnalogKid

    2,371
    661
    Jun 10, 2015
    The CD4093 is a drop-in replacement for the CD4011 and is the right part for this application. The timing will change slightly because the 4093's transition levels are different.

    If you want to stay with the 4011, add a 7.5M - 10M resistor from the output of the 2nd one to the inputs of the first one. This small amount of positive feedback will add hysteresis to the circuit, something that is built into the 4093.

    Adding reference designators and pin numbers to your drawing will make it much easier to discuss unambiguously.

    https://en.wikipedia.org/wiki/Hysteresis#Electronic_circuits

    ak
     
  7. twister

    twister

    172
    7
    Feb 12, 2012
    Thanks Bertus! This site is a big help; I've learned a lot from it. I will get some of those. Now what to do with a bunch of 4011s?
     
  8. bertus

    bertus Moderator

    752
    268
    Nov 8, 2019
  9. twister

    twister

    172
    7
    Feb 12, 2012
    Thanks Anolog
     
  10. twister

    twister

    172
    7
    Feb 12, 2012
    Thanks AnologKid. I will try the feedback resistor and see if this circuit will work till I can get the 4093.
     
  11. twister

    twister

    172
    7
    Feb 12, 2012
    Thanks Audio Guru. I want to stay with a nand gate because I use the other gates. It looks like the 4093 is what I need and I can do everything with one IC.
     
  12. Audioguru

    Audioguru

    2,873
    644
    Sep 24, 2016
    The datasheet for a CD4093 shows that with a 5V supply, its input switches at a positive-going input of 2.2V minimum, 2.9V typically and 3.6V maximum. The switching voltage cannot be adjusted.
     
  13. Bluejets

    Bluejets

    4,095
    860
    Oct 5, 2014
    Generally accepted practice to control the run of refrigeration via temperature.
     
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