Help importing

Discussion in 'General Electronics Chat' started by haloway13, Jan 17, 2014.

  1. haloway13

    Thread Starter Member

    Oct 24, 2011
    I am trying to get this circuit built in LTSpice.

    I am very new and have spent a couple hours playing with trying to get this to work.

    Can somebody please help me with directions on importing the 2 devices below as they are not in the stock package.

    *BC557B MCE 5-27-97
    *Ref: Motorola Small-Signal Device databook, Q4/94
    *Si 625mW 45V 100mA 320MHz Amp pkg:TO-92B 3,2,1
    .MODEL BC557B PNP (IS=10.2F NF=1 BF=377 VAF=121 IKF=60M ISE=3.47P NE=2
    + BR=4 NR=1 VAR=20 IKR=90M RE=0.515 RB=2.06 RC=0.206 XTB=1.5
    + CJE=24.9P VJE=1.1 MJE=0.5 CJC=8.67P VJC=0.3 MJC=0.3 TF=497P TR=345N)

    *BC517 MCE 6/19/97
    *Ref: Motorola Small-Signal Device Databook, Q4/94
    *Si 625mW 30V 1000mA pkg:TO-92B 1,2,3
    .SUBCKT BC517 1 2 3
    Q1 1 2 4 QPWR .1
    Q2 1 4 3 QPWR
    .MODEL QPWR NPN (IS=1.2P NF=1 BF=245 VAF=98.6 IKF=0.36 ISE=26.8P NE=2
    + BR=4 NR=1 VAR=40 IKR=0.54 RE=1.5 RB=6 RC=0.6 CJE=147P XTB=1.5
    + VJE=0.74 MJE=0.45 CJC=9.48P VJC=1.1 MJC=0.24 TF=60.3N TR=2.61U)

    Thank you,
    • VOX.asc
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  2. crutschow


    Mar 14, 2008
    You can put the BC557B .model file in the Standard.BJT file located in Program Files\LTC\LTspiceIV\lib\cmp. Open the standard.bjt file in notepad and cut and past from *BC557B to the end of the paragraph into that file.

    The second is a Darlington sub routine which must be put in the \sub file. It also requires a new symbol. This website has a Darlington symbol which you can import into a new Darlington folder you create in the Sym folder. You will need to modify the symbol using notepad to reference your BC517 instead of the TIP142.

    To summarize:
    The transistor models are located in the standard.bjt file.
    The symbols are located in the sym directory.
    The sub descriptions are located in the sub directory.

    Note: It's important that you generate a backup of any files you modify in case you have a problem and want to go back to the original.
    haloway13 and absf like this.
  3. haloway13

    Thread Starter Member

    Oct 24, 2011
    Thank you so much for the clear directions. I think I have succeeded in getting the two transistors in the circuit.

    How do I go about finding a simple 12V relay? I poked around a bit and even used some google fu a bit to not avail.

    Thank you!
  4. crutschow


    Mar 14, 2008
    In LTspice you can use a voltage-controlled switch (SW in parts library). You also need to add a Spice Directive (under Edit) to specify the switch's parameters and set them to match the relay parameters. Look up "sw" in the Help file. (Note that "MYSwitch" is whatever name (value) you give the switch.) If you want to simulate the coil resistance, add that in parallel with the control terminals.
  5. ericgibbs

    Senior Member

    Jan 29, 2010
  6. ronv

    AAC Fanatic!

    Nov 12, 2008
    Hi Eric. Good to see you!