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LM555: LM555 Circuit Connections

Part Number: LM555

Ronald Michallick, kindly provided the values for RA, RB and C. He also confirmed that resistors RL are not required nor the links with which they interconnect.

Is it possible for someone to please confirm that the circuit apended below is correct please?

I would be most grateful.

Thank you.

Christopher

  • Former Member
    0 Former Member

    Hello Christopher,

    The circuit shown above appears to be correctly connected as per the schematic in the previous thread.

    I am, however, not familiar with designs which use rounded edges for the traces.  Typically, we work with angles of 45 and 90 degrees.

    Regards,

    Daniel

  • Christopher,

    Are you certain that you can get a 470uF capacitor (that needs to be rated for more than 10V) in that footprint? 

    The data sheet suggest adding bypass capacitance to power pin (+15V)

    0.1 uF bypass ceramic capacitor
    1 uF electrolytic bypass capacitor

    Using equations in the data sheet , here are the results.

    The TMUX needs a VIL less than 0.8V , the LM555 can meet that need.

    The TMUX needs a VIH greater than 2V, the LM555 can meet that need.

  • Daniel,

    Our circuits are not simply about conveying electricity. Thay are about the trasmission of energy, and thus are structured in much the same way as 'Nature' structures living organisms.

    I hope I have helped you to understand.

    Thank you for your kind observation.

    Christopher

  • Dear Ronald,

    It was five o'clock this morning when I finally finished the circuit and had not had the chance to check on the resistor or capacitor availability until now.


    Is this sm version OK? if it is, I will adjust the circuit:


    Vishay Tantalum Capacitor 470μF 10V dc MnO2 Solid ±10% Tolerance TR3 Series


    Please understand that I have no intimate understanding of the minimum and maximum Input High voltage of a logic gate. Thus can I ask, whether, or not, I need to amend the circuit before I connect it to the TMUX, please?

     

    Thank you so much.

    Christopher

    PS I will post the amended circuit once complete, thank you.

     

  • Christopher,

    I have said this multiples times, but I will say it again. LM555 pin 3 can connect to the TMUX directly without any other components. 

    LM555 low output will be near 0V. This level is valid (less than 0.8V). LM555 high output will be roughly 14V. This level is valid (greater than 2V, but less than or equal to VCC, 15V).

     

  • Dear Ronald,

    I apologise that I am causing you to be exasperated with me.

    Christopher