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First Attempt at a schematic — Parallax Forums

First Attempt at a schematic

Greg LaPollaGreg LaPolla Posts: 323
edited 2009-02-27 09:04 in Propeller 1
I have been playing around with Diptrace and ExpressPCB. I think I am going to settle on diptrace. Anyways, attached is a my first attempt at a schematic. there are a few little things missing still as I haven't found/made the symbols I need. I would like to know if I am on the right track. This layout basically will use 2 thermocouples, and an inline ph meter to take readings which will be used to control 2 relays one runs a pump, the other runs a gas valve to control heat.

Greg

-edit

added a higher res jpeg

Post Edited (Greg LaPolla) : 2/26/2009 6:32:08 AM GMT
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Comments

  • mctriviamctrivia Posts: 3,772
    edited 2009-02-26 06:18
    to low res to read pin numbers but looks pretty good. is this for hobby or commercial use?
  • Greg LaPollaGreg LaPolla Posts: 323
    edited 2009-02-26 06:25
    Its for hobby use

    Greg
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-26 06:34
    it is a good practice to place a 0.1uF cap by the Vdd of every ic. but otherwise it looks pretty good. I am an eagle fan myself.
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2009-02-26 06:41
    The schematic layout looks good but are they relays you are trying to drive directly from the prop pins P4 and P5? Beware if they are, it would probably be better to use a 10cent NPN and also place a kickback diode across the coils.
    As mctrivia said it's good practice to add those decoupling caps but make sure that they are as intimate to the supply pins of the IC as possible. It cost nothing to design them in even if you don't need them all.

    *Peter*
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-26 06:45
    0.1uF are cheap. 0.00547 each

    http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=PCC1762TR-ND
  • Greg LaPollaGreg LaPolla Posts: 323
    edited 2009-02-26 06:46
    Peter,

    Thanks for the reply. The relays are solid state with and led circuit that can be driven by as little as 3 volts. Its safe as far as I can see. I posted about it earlier here
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-26 06:48
    yes i remember that post. hence the not telling you to put the diodes in this time [noparse]:)[/noparse]
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2009-02-26 06:53
    yes, but you did get to tell Greg to put capacitors in this time though [noparse]:)[/noparse]

    *Peter*
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-26 06:58
    i made the mistake of leaving them out before in other projects and had to solder them directly to the pins of the ics.
  • jazzedjazzed Posts: 11,803
    edited 2009-02-26 06:58
    Propeller VDD and VSS are horribly noisy without proper decoupling near the crystal.
    May even produce enough noise to get the FCC's attention ... pure speculation of course [noparse]:)[/noparse]

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    --Steve
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-26 07:02
    I doubt the FCC would get involved as the brodcast power would be way to low. but they sure are noisey. 0805 caps fit nicely along dip 40 pacs and if i remember correctly 0403 will work on the QFP

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Need to make your prop design easier or secure? Get a PropMod $50CAN has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module.
  • Greg LaPollaGreg LaPolla Posts: 323
    edited 2009-02-26 07:15
    jazzed,

    are you saying that caps should be placed between the crystal and the prop? on XO or XI or both? or should caps just be placed on the VDD's on the prop?
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-26 07:18
    between vdd and vss there should be a cap. make traces as short as possible from cap to vdd pin.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Need to make your prop design easier or secure? Get a PropMod $50CAN has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module.
  • Cluso99Cluso99 Posts: 18,069
    edited 2009-02-26 08:04
    Well done Greg.
    A note on your schematics. Positive supplies should always be to the top and ground to the bottom (not sideways or upside down). When you ave multiple supplies, always label the voltage (not Vdd) as it makes your circuit easy to follow. And you should always have decoupling capacitors close to the power pins on each IC. Hobbyists often get away without them, but if you get strange results it can be a pain to debug.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Links to other interesting threads:

    · Home of the MultiBladeProps (SixBladeProp)
    · Prop Tools under Development or Completed (Index)
    · Emulators (Micros eg Altair, and Terminals eg VT100) - index
    · Search the Propeller forums (via Google)

    My cruising website is: ·www.bluemagic.biz
  • Erik FriesenErik Friesen Posts: 1,071
    edited 2009-02-26 13:08
    One thing nice about diptrace is that all parts in the schematic will have an attached pattern. When you create pcb it will populate all the parts. It makes creating the schematic take a bit longer though.
  • Ken PetersonKen Peterson Posts: 806
    edited 2009-02-26 13:17
    You have a couple of signal lines crossing your power supply section that don't seem to be related to the power supplies. Just looks a little confusing. Other than that, pretty good.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    ·"I have always wished that my computer would be as easy to use as my telephone.· My wish has come true.· I no longer know how to use my telephone."

    - Bjarne Stroustrup
  • Greg LaPollaGreg LaPolla Posts: 323
    edited 2009-02-26 14:50
    mctrivia,

    is 0403 a type of cap ? also should this cap go between vss & vdd or just vdd to gnd ?
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-26 15:28
    vss is the digital prop ground.
    0403 is a size of surface mount component very small. I normally work with 0603 components as they are easy to work with and still very small. you still need twezers though

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Need to make your prop design easier or secure? Get a PropMod $50CAN has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module.
  • Greg LaPollaGreg LaPolla Posts: 323
    edited 2009-02-27 04:28
    Ok,

    Round 2. I made some changes. Regarding the feedback. See attached.


    My next item to attack is surface mount. I an kinda old school when it comes electronics. I learned from my Grandfather on tube TV's and ham radio's back in the seventies.


    Is there some documentation or websites with data relating to this as to determining what is needed? I assume since they are so damn small they don't use color codes anymore.


    I have been watching ebay and seeing small soldering ovens and rework stations in the 300-400 dollar range. That seems to be a fair price. Is surface mount somthing that is easy to do with the right equipment or should I just contract the whole thing out? I would like to keep the cost of this little project as low as possible. However there is a small possibility that what I am creating could spark some interest in my little circle of friends so there may be a need to make a few more than what I need.


    Greg
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  • mctriviamctrivia Posts: 3,772
    edited 2009-02-27 04:45
    i work almost entirely with surface mount components. There is no need for a soldering oven. They make things easier but a toaster oven with a quartz element will work just as well.

    If you are doing a lot of surface mount I highly recomend spending the extra money and buying the JBC AD2700 its ability to heat up instantly and change tips while hot is a life saver. With surface mount you need to change tips for different size and shaped components. The tips are very expensive but I have not had to replace one yet. Unlike welers tips that i use to change weekly.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Need to make your prop design easier or secure? Get a PropMod $50CAN has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module.
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-27 04:47
    schematic looks good.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Need to make your prop design easier or secure? Get a PropMod $50CAN has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module.
  • Greg LaPollaGreg LaPolla Posts: 323
    edited 2009-02-27 04:56
    Thanks for the link. You can actually solder a surface mount chip with that? I guess you need a good magnifier and a study hand!
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-27 04:56
    oh 1 more thing. never use a sponge with your soldering iron. get a gold plated whole for cleaning tip. temperature drop from using a sponge kills tips of any kind.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Need to make your prop design easier or secure? Get a PropMod $50CAN has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module.
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-27 04:58
    a microscope makes things easier but i do it with just my bare eyes. steady hand is a must. so is solder whick

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Need to make your prop design easier or secure? Get a PropMod $50CAN has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module.
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-27 05:00
    my propmod is entirely made of surface mount components. has to be. the whole thing is just slightly biger then the dip package and includes programing head, eeprom, crystal, and a uSD card reader.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Need to make your prop design easier or secure? Get a PropMod $50CAN has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module.
  • Greg LaPollaGreg LaPolla Posts: 323
    edited 2009-02-27 05:03
    I am a little shaky from years at the keyboard coding. ( carpol damage) I always have a spool or 3 of solder whick laying around.

    Do you work solely with this or do you also use an oven ?


    Greg
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-27 05:05
    i don't use an oven. i have seen it done and read articles in circuit celler about it.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Need to make your prop design easier or secure? Get a PropMod $50CAN has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module.
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-27 05:06
    if you need surface mount and don't trust your hands i can make up and assemble boards for reasonable price.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Need to make your prop design easier or secure? Get a PropMod $50CAN has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module.
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-27 05:07
    what surface mount parts were you looking to use?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Need to make your prop design easier or secure? Get a PropMod $50CAN has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module.
  • Greg LaPollaGreg LaPolla Posts: 323
    edited 2009-02-27 05:09
    Well, I will have to wait a few weeks to make that purchase. I have spent a lot on the paralax website in the last few weeks. I have purchased almost all the stamps in class for my son. Trying to get him into electronics and off the computer games!

    I need to do some research about smt before I take the next step.

    Post Edited (Greg LaPolla) : 2/27/2009 5:21:32 AM GMT
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