Question about planning out your power source.

Discussion in 'The Projects Forum' started by blake11, Feb 20, 2010.

  1. blake11

    Thread Starter New Member

    Feb 20, 2010
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    I am new to the world of electronics, and I was wondering if any of you guys could help me by looking over a project that I am currently working on. I have all the individual pieces planned out, but I want to make sure I am going about this the most efficient way as possible.

    The project is going to involve an Arduino Duemilanove, 20 80mA LEDs, 20 20mA LEDs, and 20 QRB1114 Sensor/Emitters.

    There will be 20 individual modules consisting of 1 80mA LED, 1 20mA LED, and 1 QRB1114.

    I guess my question is, what is the best way to get all these things power?

    Here is a layout that I drew up. Please hold back on the mocking of my drawing. I just downloaded EAGLE for the first time, and I really don’t know what I’m doing.

    Please do not pay attention to the part numbers on the drawing. Like I said, I am new to EAGLE, and I am not sure how to find all the correct parts at the moment.
    [​IMG]

    The 3 open ended lines are going to my going to my LED driver and Arduino.
    I thought this would be the best way to keep all the wiring down to a minimum.

    Does this look ok? I was planning on running all the vcc and ground lines to a central bus, I guess you would call it.

    Are using the transistors a good idea? I thought of using those so I am not trying to power all the lights off 3 16bit LED drivers.

    And the last question... How to calculate the power source for such a project? I'm not asking anyone to do it, just wondering what things I should be looking for. I was hoping to have everything running off my 5v Arduino with the source coming from the wall.

    Any and all comments are welcome. Thanks in advance for any feedback.
     
  2. hgmjr

    Moderator

    Jan 28, 2005
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    It would be helpful to have a few more details about what your design is going to be used for.

    hgmjr
     
  3. blake11

    Thread Starter New Member

    Feb 20, 2010
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    The schematic above is that of just a single module. there will be 20 in total.
    At anytime 20 LEDs will be on, 1 on each board. Which one will be determined if something is within the range of the sensor that is on the board. So worst case scenario, all 20 of the blue 3.4v 80mA LEDs will be on at the same time because all 20 sensors will be covered.
     
  4. hgmjr

    Moderator

    Jan 28, 2005
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    It looks like each of your modules will consume 80+20+20+10 or about 130 milliamps. 130 times 20 is yields an estimated 2.6 Amps. Without all your schematic, I cannot determine what other current is likely to be.

    Have you decided what your main voltage source is likely to be?

    hgmjr
     
  5. blake11

    Thread Starter New Member

    Feb 20, 2010
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    Well the rest of the schematic is really just 19 more of those :). Each one will have 2 inputs coming from a LED Driver, and the output of the phototransistor going to a 8-bit shift register (gotta save the pins on the Arduino). Should I think of replacing that 80mA blue led for another lower current one. It does seem like a power hog, but it seems all the blue ones seem to draw more current. I am hoping to have a single power bus coming from a wall source.
     
  6. retched

    AAC Fanatic!

    Dec 5, 2009
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    There may be a better way. The sensors are trip sensors? Do you want each of the 20 LEDs to individually light at different brightness or just ON/OFF ? And What will determine when which color led lights? Why do you need a separate LED driver and why would you need the Arduino at this point?

    If you want a sensor respondent led, it could be done easier. What task is the Arduino performing?
     
  7. blake11

    Thread Starter New Member

    Feb 20, 2010
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    The LEDs only need to be in an ON/OFF state. The reason I am using the LED Drivers and 8-Bit shift registers is because the pattern of the lighting will vary depending on what sensors are currently set high. The Arduino will determine which sensors currently have an object in front of them and adjust which modules need to be blue and turn the modules with nothing in front of them white. Hope I am not being concise enough.
     
  8. retched

    AAC Fanatic!

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    The sensors can do that without the arduino. Normal (not blocked) show white, blocked show blue

    You could just use the sensor, two leds, teo resistors and two transistors. (per segment)

    Tell me if im wrong.. But you are going to have 20 of these layed out.. say a 4 x 5 pattern. They will all be white unless something passes the sensor that will make the light turn blue, when the sensor cant see it anymore, it turns back to white. Is that correct?

    the logic can be controlled by the sensor and transistor
     
  9. blake11

    Thread Starter New Member

    Feb 20, 2010
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    I guess it would be easier to just put it out there what I am trying to make. I am making a beer pong table. The modules will be placed 10 a side in a triangular pattern. The reason I am using the Arduino, when the cups get down to 6,4, or 3 cups, I want to the table to realize this and start flashing the lights where the cups need to be placed to reshuffle. I have that part down right now (in a smaller scale).

    So, the table is turned on, and all the white lights are showing. As the cups are placed over their spots, the white likes are set low because the sensor has went high and the Arduino turns on the blue lights. As the cups are removed, the empty spots then turn white. As more cups leave the table and it hits 3,4,or 6 cups left, the spots where the cups need to move begin flashing until cups are placed over there.

    I have all this done right now in the a six module set up, I just don't know how to handle the power distribution for a bigger scale. I am thinking that I will modules in the schematic above. I will have a 3 male header off the module (so I can use the JST connectors for easy change out) that will feed to the LED driver module and Parallel IN/Serial Out module I am making that talks to the Arduino. The the power and ground will come of a 2 male header to a bus that is getting power from a wall source.

    So, do I add up all the individual modules amp requirements and calculate the power required to run the 5v Arduino, the just find a wall adapter that can put out enough current?

    Thanks for helping fumble through my first real project. :)
     
  10. retched

    AAC Fanatic!

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    Yes, thats about it. Figure the total amperage and voltage your project will use and get a wall wart that hits or slightly exceeds it. Now after you have the wall wart, check it with your meter to see the "actual" loaded supply. You will calculate the resistors needed for the components from the power supply you choose.
     
    blake11 likes this.
  11. blake11

    Thread Starter New Member

    Feb 20, 2010
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    Thanks retched... Now here comes the ultra noob questions. I understand about calculating the required current for the project, but how does the overall voltage required play into this?
     
  12. retched

    AAC Fanatic!

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    well the voltage is going to be determined by each "spot" there is only going to be 1 LED on at a time, so choose for the voltage drop of the largest led and the requirements of the sensor. In the datasheet for the QRB1114, they test at 5v. So that you will want at least 5v for the QRB1114 after the voltage drop of the blue led. so if the blue led drops 3.3v + 5v for the QRB1114, you want at least 8.8v.. So you can use a 9v supply.

    Now you need enough amperage from the supply to handle all 20 units. about 2.6 amp.

    [ed]
    Here is a 9v 3a:
    http://azsurplus.com/index.php?main_page=product_info&cPath=1_39&products_id=697
    [/ed]
     
    Last edited: Feb 20, 2010
  13. hgmjr

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    Jan 28, 2005
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    Don't forget to include the Arduino's power requirements in the overall power budget.

    hgmjr
     
  14. retched

    AAC Fanatic!

    Dec 5, 2009
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    True. If you get the power supply I linked to, you should still have room for the Arduino..I forgot to add that in.. Thanks hgmjr. The arduino will allow 40ma max per port so if you used 1 port for the shift register, and your shift register, you should come in at around 120ma.

    A 9v battery will run an arduino at high processing for about 170hours
    http://wiki.bennington.edu/wiki/Power_Requirements_for_Arduino,_various_parts
     
  15. blake11

    Thread Starter New Member

    Feb 20, 2010
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    You guys are awesome. Thanks for the advice and the patience :). I have been stalling on the project because I was nervous to make the next step. Now I can move on and make it happen.
     
  16. retched

    AAC Fanatic!

    Dec 5, 2009
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    It's true, we are. :p

    This is a great place to do some learn'n.
     
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