ExpressSCH help with transistors

Discussion in 'The Projects Forum' started by magnet18, Jan 23, 2011.

  1. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    Hi everyone,
    Im working on making a schematic in ExpressSCH for my nixie clock so that I can transfer it to ExpressPCB, print it, etch it, the whole dealio.

    My problem is that when i check the schematic for netlist errors, as soon as it comes across the second transistor (or any transistor but the first), i get the error in the attached image

    I originally thought this error might have been because it was connected to a custom part NIXIE tube, but i get the same error regardless of what the transistor is connected to.

    I really have no idea why it does this, it doesent have any problem with the first transistor, only every one after it.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Have you followed the directions? Notice that each transistor has a partial designator - Q. For the net to be able to know which transistor is being connected, you must assign a part number to the device. Right click each transistor and select "set component properties". At the top of the resulting menu is a space where you can insert a number next to the "Q" so the transistor becomes unique in the schematic.
     
  3. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    yea, i did that originally, i forgot to do that for this screenshot but it makes no difference, as you can see in the attachment.

    [EDIT] To the moderators, i apologize if this should have been posted in the electronics resources section, if you can/wish to move it there please do so.
     
    Last edited: Jan 23, 2011
  4. Wendy

    Moderator

    Mar 24, 2008
    20,766
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    The problem I ran into with ExpressPCB (I'm fresh on using it) is you need to designate which pins are 1, 2, and 3. Many packages have the pins designated as numbers, but the components in ExpressSCH don't have their pins numbered. It is up to the user to define these pins, you will end up with a custom component doing so.

    Go to your ExpressSCH, ungroup the transistor component, then add the numbers as the attributes, making sure it matches the number on the package in ExpressPCB. The little dots on the end of the wires for Q1 and Q2 need to have the attributes changed and pin numbers added.

    The reason they do this is there are just too many configurations out there. This allows you to match the transistor to the case.
     
    Last edited: Jan 23, 2011
    magnet18 likes this.
  5. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    thanks bill,
    do i need to do this for each transistor individually (i have 44)?
    do i need to do this for any other components (ic's, diodes)?

    and, on a similar note, is the best way to put a nixie tube in the schematic to just create a standard component or is there a different procedure sine they are round and not exactly a normal component?
     
  6. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
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    I think because of the variety of pin number arrangements (1, 2, 3) of transistor cases vs the pin designations on the schematic, there are no pin numbers assigned in those schematic transistors. The schematic transistor pins must match the PCB transistor pins.

    To correct it, add a "Semiconductor - Transistor NPN" from the component list.
    Highlight the transistor.
    From the Component pull-down list, select Ungroup.
    One at a time, double-click on a pin and assign a number to it and Save. For a T0-92 case, the collector is #1, the base is #2 and the emitter is #3.
    When done, highlight all of the transistor's parts.
    From the Component pull-down list, select Group.
    Give it a Part ID of "Q" and Save.
    From the Component pull-down list, select Save Custom Component.
    Name it "Transistor NPN - T0-92" and Save.

    For other semiconductor cases, pull them up in the PCB window. Check the pin numbers with the Tool on the left ( O? ). Then go back and make a custom schematic symbol for each transistor case.

    Ken

    OOPs! Bill beat me to it.
    The transistors are the only ones I've found that need this done to. Once you save them as custom components, they are always there to reuse.
    You can just make a component (box) named NIXIE and add correctly numbered pins. If the Nixies are off-board you just use "wire connections"
     
    Last edited: Jan 23, 2011
    magnet18 likes this.
  7. Wendy

    Moderator

    Mar 24, 2008
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    No, like I said, when you are finished you will have a custom component. You will need to replace all the transistors with the new part, but even with 44 of these parts it isn't a big deal.

    All the components have pins numbered, the most likely culprits will be 3 terminal semiconductors. I had some problems with capacitors on my project.
     
    magnet18 likes this.
  8. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    Thanks to both of you, i can get back to work now :)
     
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