quarta-feira, 29 de maio de 2013



EXPRESS PCB TUTORIAL
Revised 1/11/2010

This tutorial leads you through the design of a PCB using layout software from ExpressPCB, which is freeware available at www.expresspcb.com.    Before beginning you should make sure your computer has both ExpressPCB and ExpressSCH, if not than you should download the software.   Before beginning the PCB process, you should come up with the initial design, build it and test it on a breadboard, fix any errors, and determine specific components.  It is also useful to have datasheets and dimensions for all of the “special” components such as transistors, ICs, sensors, actuators, etc., on hand.  For this tutorial, we will use a drawer burglar alarm circuit, which had the following form after testing on a breadboard:
There are two stages remaining in the process to creating the circuit board.  In the first stage, you build the schematic using the ExpressPCB schematic editor.  In the second stage you layout the circuit board.  It is possible to skip directly to the layout editor.  However, doing the schematic first will allow you to link the schematic into the layout editor reducing the probability of error.

Entering the Schematic into ExpressSCH

  1. Open ExpressSCH to create a fresh schematic.  The first time you start ExpressSCH you will get a dialog box with a link to a quick start guide for ExpressSCH.  This can be useful if you want to get a general overview for the tool.  Once you are ready to start, close the dialog box to view the empty schematic.

  1. Click on Op-Amp-like symbol to place components.  To place the resistors, select “Passive-Resistor” in the text box in the upper right corner.

  1. Then click on the schematic for the 4 resistors (not including the photoresistor or potentiometer) in roughly the location you want them to display.  Then zoom in using the magnifying glass tool (or the wheel on the mouse) and pan the display (using the sliding bars) to improve your view.

  1. Now you need to give each of the resistors unique identifiers.  Right click on a resistor and choose “Set component properties.”  In the Component Properties box, under “Component ID,” select “Auto assign Part ID.”  The program should assign this resistor to be R1.  Set its value 10k in the “Part Name” field and hit OK.  Repeat this process to identify and label   R2 (10k), R3 (100k), and R4 (10k).

  1. Rotate R4 by right clicking on it, selecting “Rotate component” and then “Body left 90º”


  1. Now add the capacitor, potentiometer, comparator, and transistor to the circuit by first clicking back on the component placement tool (the red op-amp symbol) and using the component names “Passive-Capacitor polarized,” “Passive- Potentiometer,” “IC – National  - LM311 – Comparator – DIP-8,” and “Semiconductor – Transistor NPN.”  Use “set component properties” to assign all of these parts Part IDs, label them and position them (using the arrow tool) in a logical manner.

  1. Now we need to add some components (the photoresistor and the buzzer) that don’t exist in the library.  Let’s start with the photoresistor.  The easiest way to make new parts is to start with a symbol that’s already close to what you want and modify it.  Place a regular resistor on the layout (using the placement tool with ‘Passive – Resistor’).  Go to the selection tool (the arrow), choose that resistor and go to the “Component” menu at the top and select “Ungroup component”

  1. Using the circle shaped tool from the tool menu, draw a circle around the resistor.

  1. Select the whole object (using the arrow tool), and choose “Component” -> “Group to make component”

  1. In the component properties box that appears, assign the photoresistor a unique part ID, such as “PR1”.

  1. For future use, save this as a custom component by selecting “Component” -> “Save custom component” and then in the dialog box that appears give the component a name such as “photoresistor.”  (If someone else has already completed the tutorial on this computer, the part may already exist, in that case you should either save this component with a unique name, or save your component on top of the one already existing)

  1. Move the photoresistor to the spot you want it in the circuit.
  2. Now we will create the buzzer.  The buzzer is a polarized device, so a good starting point is a polarized capacitor.  Go to the component selector, choose a polarized capacitor, ungroup the capacitor, and then add a circle to the symbol to distinguish it as a buzzer.  Group the entire object as a component with part ID, “BZ1,” and label “CEP-2224” and save the component as a “Buzzer” under custom components.  At the last step, you’re display will be as follows:

  1. Now we need to add our connections to power and ground.  Let’s start with ground.  Go to the “symbol or signal label” tool, which looks like a ground, and select “Power – ground” from the text box in the upper right. 

  1. Place 5 grounds into the circuit, at the bottom of R2, near pins 1 and 4 of the LM311, near the bottom of the capacitor, at the emitter of the BJT, and at the bottom of the potentiometer.

  1. Repeat this process, but using “Power – Voltage Supply +9V” to put 5 power connections in at the top of R1, the photoresistor, pin 8 of the LM311, the top of R3 and the top of the buzzer.

  1. Now let’s add in our battery connection.  Place a battery into the circuit, using “Misc – Battery.” Assign the battery the part ID “B1” and give it the label “9V.” Then, use the symbol tool to add a ground connection and a +9V network connection (this will link the positive terminal of the battery with every other point in the circuit that should go to 9V—if you wanted to add a switch to the circuit, you would add it between the + terminal of the battery and the ‘+9V’ symbol.)

  1. Now select the wire tool, and wire your circuit together. The left-click starts the wire and sets a bend, and the right click ends a wire.  After wiring, the schematic should appear as follows:

  1. Save your work, using “Save As..” to create a unique filename.
  2. Check your file for netlist errors using “File” -> “Check schematic for netlist errors”

  1. The pins inside of the BJT are not specified (this is because pin assignments vary for different BJTs) so you will probably will get an error message, like that shown below:

  1. Hit “cancel” on the error message, and then as that message suggested, select the part and choose “Component” and then “Ungroup Component.”  This example uses the 2n1711 BJT in the little tin can (the TO-39 package).  For this package the base is pin 2, the emitter is pin 1, and the collector is pin 3.  To set this in the schematic, double click on just the collector pin, and assign it to pin 3.

  1. In a similar fashion, assign “2” to the base, and “1” to the emitter.  Then select the entire component (this takes a lot of shift-clicking—be sure to get all the little parts), choose “Group to make component” from the Component menu, and assign the part ID to be Q1.
  1. If you’re going to be using the transistor again, it’s probably a good idea to then click on it, select “Component” -> “Save custom component” and save it as the transistor name, which in this case is 2n1711. 

  1. Now check your file for netlist errors again, using “File” -> “Check schematic for netlist errors,”  you might get an error like that shown below (if not skip to #28)

  1. The cause of this error is that the wire isn’t really connected.  The “snap-to-grid” function has prevented you from making a connection.   Hit continue to exit the netlist check.  Then toggle the “snap-to-grid” function off, select the errant line end(s) and move it (them) into the correct position.  Repeat this process until all the lines are properly connected.
 

  1. Reattempt the netlist error check.
  2. Once the netlist error check runs clean, you will be asked to save your file, which you should definitely do.  The final schematic should look like this:

  1. Print your schematic to reference as you work on your layout.  At this point, you should review your schematic carefully to check for errors.  Once you are satisfied that the schematic is correct, close ExpressSCH.


26 comentários:



  1. Nice post. I am really impressed with your article, such great information you mentioned here..

    ResponderExcluir
  2. With havin so much content do you ever run into any problems of plagorism or copyright violation?
    My blog has a lot of completely unique content I've either created myself or outsourced but it appears a lot of it is popping it up all over the internet without my agreement. Do you know any solutions to help stop content from being ripped off? I'd certainly appreciate it.



    Here is my web site: please click the following post

    ResponderExcluir
  3. Thankfulness to my father who informed me concerning this website,
    this blog is really amazing.

    Review my web site http://www.kainuunsuunnistus.fi/index.php?Itemid=23&option=com_fireboard&func=showcat&Go=Siirry&catid=0

    ResponderExcluir
  4. Thanks for finally talking about > Sem título < Liked it!

    Here is my site :: merchant account systems

    ResponderExcluir
  5. Howdy! Would you mind if I share your blog with my zynga group?

    There's a lot of people that I think would really appreciate your content. Please let me know. Thank you

    Here is my web blog; http://barbecuebible.com/mediawiki/index.php/...iecxsappyn ()

    ResponderExcluir
  6. Does your website have a contact page? I'm having a tough time locating it but, I'd like to send you an email.
    I've got some ideas for your blog you might be interested in hearing. Either way, great blog and I look forward to seeing it develop over time.

    Look into my website: http://afistfullofplastic.blogspot.com/2013/0...antry.html ()

    ResponderExcluir
  7. Wow, incredible blog layout! How long have you been blogging for?
    you make blogging look easy. The overall look of your website is great,
    let alone the content!

    Here is my site ... www.e-guernica.net/wiki_scuola/BeverlyccScogginscp ::
    :
    :

    ResponderExcluir
  8. Thanks for a marvelous posting! I seriously enjoyed reading it, you may be a
    great author. I will make sure to bookmark your blog and may
    come back sometime soon. I want to encourage you to continue
    your great work, have a nice morning!

    Feel free to surf to my site; just click the next webpage

    ResponderExcluir
  9. Thanks on your marvelous posting! I quite enjoyed
    reading it, you're a great author.I will remember to bookmark your blog and will come back someday. I want to encourage one to continue your great job, have a nice evening!

    Here is my webpage - http://www.bobbertalk.com/profile.php?mode=viewprofile&u=87682 ()

    ResponderExcluir
  10. Greetings! Very useful advice within this post! It is the little changes that make the greatest changes.
    Many thanks for sharing!

    my web site Oldenburg

    ResponderExcluir
  11. I do accept as true with all the ideas you have offered in your post.
    They're really convincing and will definitely work. Still, the posts are very quick for novices. May you please extend them a bit from next time? Thank you for the post.

    Here is my web site ... cockernony

    ResponderExcluir
  12. Thankfulness to my father who stated to me on the topic of this weblog, this website is actually remarkable.



    Stop by my site ... http://www.republicofmining.com/2013/05/31/18bn-cut-for-pilbara-iron-ore-miners-by-malavika-santhebennur-australian-mining-may-31-2013/ - -

    ResponderExcluir
  13. My brother suggested I might like this web site. He was entirely
    right. This post truly made my day. You can not imagine just how much time I had spent for
    this info! Thanks!

    My blog post; Numbers@buy peptides

    ResponderExcluir
  14. I need to to thank you for this good read!! I definitely enjoyed every little bit of
    it. I've got you book-marked to check out new things you post…

    Check out my blog post: http://www.usaucbi.com/web/Shownews.asp?id=10439

    ResponderExcluir
  15. Thank you for sharing your thoughts. I really appreciate your
    efforts and I will be waiting for your further write ups thanks once again.


    Here is my blog post :: demos1.softaculous.com/WikkaWiki/LavadaddGaffneylq

    ResponderExcluir
  16. Hey would you mind letting me know which web host you're working with? I've
    loaded your blog in 3 completely different internet browsers and I must say this blog
    loads a lot faster then most. Can you recommend a
    good web hosting provider at a reasonable
    price? Many thanks, I appreciate it!

    My website: intracerebellar

    ResponderExcluir
  17. Howdy! Would you mind if I share your blog with my myspace group?
    There's a lot of people that I think would really enjoy your content. Please let me know. Thanks

    Here is my web page ... click through the following internet site

    ResponderExcluir
  18. Great post. I was checking continuously this blog
    and I'm impressed! Extremely useful information specifically the last part :) I care for such information a lot. I was seeking this particular info for a long time. Thank you and best of luck.

    Feel free to surf to my web-site - steroids powder

    ResponderExcluir
  19. Asking questions are in fact good thing if you are not understanding something totally, but this article gives nice understanding even.


    Feel free to surf to my weblog - mouse click the up coming web site ()

    ResponderExcluir
  20. I have been surfing online more than 4 hours today, yet I never
    found any interesting article like yours. It is pretty worth enough for me.
    Personally, if all website owners and bloggers made good content as
    you did, the net will be a lot more useful than ever before.



    Also visit my homepage ... http://seotips4ru.blogspot.co.uk/search?q=

    ResponderExcluir
  21. This is really interesting, You're a very skilled blogger. I have joined your feed and look forward to seeking more of your fantastic post. Also, I have shared your site in my social networks!

    Feel free to surf to my web blog ... bountith

    ResponderExcluir
  22. This blog was... how do you say it? Relevant!
    ! Finally I have found something that helped me.

    Thank you!

    Look at my website iesjoanfustersueca.edu.gva.es/.../view.php

    ResponderExcluir
  23. We're a group of volunteers and opening a new scheme in our community. Your site offered us with valuable information to work on. You have done an impressive job and our whole community will be thankful to you.

    My blog: wedlock

    ResponderExcluir
  24. Hello are using Wordpress for your blog platform? I'm new to the blog world but I'm trying to get started and set up my own.
    Do you require any coding knowledge to make your own blog?
    Any help would be really appreciated!

    Here is my weblog: Post Comment

    ResponderExcluir
  25. This paragraph will assist the internet users for setting up new weblog or even a blog from start to end.


    My weblog; Link Website ()

    ResponderExcluir
  26. There is definately a great deal to know about this
    issue. I love all of the points you've made.

    Feel free to visit my web blog http://theploneblog.onenw.org/author/DarylJank :: ::

    ResponderExcluir