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Propeller Servo Controller USB: idea: — Parallax Forums

Propeller Servo Controller USB: idea:

Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
edited 2009-09-08 21:55 in Propeller 1
I was looking a Propeller Servo Controller USB and thinking
that this might make a really nice control for those 5v/110v relays for a Propeller based Christmas display.

Hmm.. Wonder if I could finish PropMAN in time to start working on something like this from Christmas.

OBC

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Comments

  • blittledblittled Posts: 681
    edited 2009-09-08 16:15
    OBC,

    Were you thinking of using a ULN2803 or optoisolators to get enought current and voltage to drive the relays?

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    What electronics need - MORE POWER!!!!!!!
  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2009-09-08 16:20
    IANAEE,

    These shouldn't draw much more than a servo?

    www.radioshack.com/product/index.jsp?productId=2062479

    OBC

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    New to the Propeller?

    Visit the: The Propeller Pages @ Warranty Void.
  • Ken GraceyKen Gracey Posts: 7,401
    edited 2009-09-08 16:22
    Hey Jeff!

    Chris Savage has defined a really versatile relay board that we will sell in a kit. He and Thomas are 50% the way through the second PCB revision. I'll see if I can round him up for a comment on this thread. He can tell us all about it.

    - Ken
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2009-09-08 16:28
    OBC,

    That link points to 12V reed relays. The output of the PSCU is 5V. Even if you used 5V reed relays you’re still driving a coil (inductive device), so at minimum you’d want a 1N914 diode in reverse bias across the coil terminals. I will have to look at the datasheet for the level translators though to see how much current they can source/sink. While the board was design with the prospect of driving many types of devices, you still have to factor in the unique interface requirements of said devices. Take care.

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    Chris Savage

    Parallax Engineering
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  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2009-09-08 16:36
    OBC,

    Ok, so these level translators (TXB0108)…I remembered in my article showing the interface as being a MOSFET and I was just now reminded of why…you see, these devices have to have high-impedance on the output and they’re not meant to drive a load of any kind. Not even an LED. Any load should be driven from a MOSFET. That would be the best way to drive anything from an SSR to a Solenoid. I hope this helps. Take care.

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    Chris Savage

    Parallax Engineering
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  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2009-09-08 16:49
    Hey just as an FYI, we’ve designed an Industrial I/O Control Board that is more geared toward driving loads. The controller has 8 optically isolated inputs and 8 isolated outputs. The outputs can be Omron mechanical relays or SSRs. The interface has both parallel I/O and an SPI-type interface to conserve pins. This is just about ready for manufacturing so it won’t be too long. This will most likely be a kit that you build using through-hole parts, so be prepared to get your hands dirty. =)

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    Chris Savage

    Parallax Engineering
    50 72 6F 6A 65 63 74 20 53 69 74 65
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  • Adam WieslerAdam Wiesler Posts: 81
    edited 2009-09-08 18:43
    About the Christmas lights, I wouldn't use mechanical relays, they are high current and can only operate so many times. I designed a prop-based light controller that used mini -ssrs to control the lights. I think that they were rated at .9amps@110v and were in a dip-8 package. They can be driven off of 5v easily. Check out my website(in my signature)

    BTW i was using my ssr and prop boards to control the 18 segment vu meter that i had at upene.

    @parallax, neat i've been wanted an easy to use relay board for a while now. In fact, I spent some of my summer break designing a prop relay board with digital outputs, inputs, and an interface header for ucontroller.com's ethernet adapter.

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    My website www.quigleyelectronics.com/
  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2009-09-08 19:44
    @Chris:

    Thanks for the very complete input!


    @Ken & Chris: Any chance these relay boards will be available by Turkey day 2009??
    I love the idea of them being a kit! Wonderful! I'd love to do a Propeller light show this year!


    @Adam: It almost sounds like I could use that solution with the existing board! Hmmm..


    OBC

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    New to the Propeller?

    Visit the: The Propeller Pages @ Warranty Void.
  • Adam WieslerAdam Wiesler Posts: 81
    edited 2009-09-08 20:02
    Oh, another thing, mechanical relays can't be dimmed.

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  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2009-09-08 21:55
    @OBC, since the product is meant to be a kit it could be realized rather quickly, but I still couldn’t answer for any kind of timeline.

    @Adam, SSR’s can’t be dimmed either, but they do at least allow the option of PWM to simulate dimming, if that’s what you meant. Certain SSR modules would not work well though such as those with zero-crossing detection. Take care.

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    Chris Savage

    Parallax Engineering
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