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Circuit design help needed

Discussion in 'General Electronics Discussion' started by WHYnot, Apr 19, 2016.

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  1. WHYnot

    WHYnot

    18
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    Apr 19, 2016
    Hi

    I am trying to put together a circuit that has 3 buttons for control.

    Button 1: Power on/Select output
    Button 2: Enable output
    Button 3: Power off

    Each output needs to oscillate the same bank of LEDs but at 5 different preset frequencies (frequency preset chosen with select button).

    It is a battery powered circuit with a DC plug to be charged by a 7.2V 750mA DC adapter
    Low battery and charging indicator LED
    Overcharging protection
    Batteries are 3.6V 600mAH NiMH

    I have each circuit schematic for each function however I would like to know if there is an easier way to incorporate this into a 1 x IC cuircit at a reasonable cost.

    Thanks in advance
     
  2. dorke

    dorke

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    665
    Jun 20, 2015
    Welcome to EP.
    Please explain what do you mean by:
    "oscillate the same bank of LEDs but at 5 different preset frequencies".
     
  3. WHYnot

    WHYnot

    18
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    Apr 19, 2016
    Hi, Thanks.
    I mean flash the LED on and off at a set frequency.
     
  4. dorke

    dorke

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    Jun 20, 2015
    So you have 5 different square waves at various frequencies.
    Are they all present at all times ,or do you create the needed one only when it is needed?

    The Power ON/OFF is a simple switch on the battery voltage.
    The Enable Output can be merged with the ON/OFF switch.
     
  5. WHYnot

    WHYnot

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    2
    Apr 19, 2016
    They can be created when needed or always present when the circuit has power on.
     
  6. dorke

    dorke

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    Jun 20, 2015
    I think I have misunderstood your question.
    You already have the full design and wont to have it in single IC.
    That is possible in several ways ,
    It depends on the design size, is it digital only(without the battery charging),
    and most of all the quantities you are talking about.
     
  7. WHYnot

    WHYnot

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    Apr 19, 2016
    Yes that is all correct.
    I am doing it for a personal project. Just experimenting at this point.
     
    auxuscg likes this.
  8. Herschel Peeler

    Herschel Peeler

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    Feb 21, 2016
    Can you deal with a microcontroller based design?
    Are you looking for somebody to build it for you?
    Do you already have a basic design in mind?
     
  9. WHYnot

    WHYnot

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    Apr 19, 2016
    Microcontroller would be fine.
    I can do the build, just looking for design.
    I do not have a design as of yet.
     
  10. Herschel Peeler

    Herschel Peeler

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    Feb 21, 2016
    Do you have a preference for a microcontroller. All lines are simple digital. A cheap PIC16 or Arduino??
    For mass production or just a one time thing?
     
  11. WHYnot

    WHYnot

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    Apr 19, 2016
    At the moment I am putting together a prototype which will hopefully go into mass production. No preference.
     
  12. Herschel Peeler

    Herschel Peeler

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    Feb 21, 2016
    For mass production Arduino may not be a first choice. PIC16xxx might be better. Do you have devices in stock? What sources do you usually buy from? US market?

    http://www.jameco.com/Jameco/Products/ProdDS/312590MCH.pdf
    If the link works, PIC16F684, cost about $1.55 in small quantities.
    12 digital I/O lines. 8 Analog input lines. plus much more. 10-bit ADC gives a resolution of about 5 mV on a 5 V signal. Barely sufficient for noticing battery voltage charging. Do you need more precision?
     
    Last edited: May 9, 2016
    WHYnot likes this.
  13. WHYnot

    WHYnot

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    Apr 19, 2016
    I am still in prototyping phase so nothing in stock. I normally get my stuff from a company here in Cape Town South Africa: Mantech Electronics.

    That looks great!
    Where would I be able to find someone to write the code for me?
    Thanks for the help!
     
  14. Herschel Peeler

    Herschel Peeler

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    Feb 21, 2016
    You might find somebody here or other forums that might do it for a fee. You don't have a programmer yourself? I don't know Mantech But the chip is pretty common at a similar price.
    (edited to add ...)
    Yes, Mantech has the chip at R15.15 (a bit over $!.00 US.
    I didn't check but they probably have a cheap programmer also. This would be a good "My first project" for you.
     
    Last edited: May 9, 2016
    WHYnot likes this.
  15. WHYnot

    WHYnot

    18
    2
    Apr 19, 2016
    Great stuff.
    I do have a programmer but don't know anything about writing code.
    Thanks again for your help.
     
  16. Herschel Peeler

    Herschel Peeler

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    Feb 21, 2016
    330M0129 from Mantech. About R 2,000 ($135. US). comes with a PIC16F690, which is quite suitable to your needs. A great learning experience awaits you.
    Or you can go to a handful of ICs and headaches. :)
     
  17. Herschel Peeler

    Herschel Peeler

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    Feb 21, 2016
    Looking at the forums I go to nobody wants the job. The job of programming for another party that isn't specific about their needs makes for a potential unhappy customer. You are looking at small bucks to get into doing it yourself versus thousands of dollars US to pay somebody else to do it and never be happy or have somebody to make alterations for you, which is certainly going to happen.
    Hiring a programmer is a tough job for an experienced programmer and manager.
    Find somebody locally. Or maybe China, Japan or So. Korea.
     
  18. WHYnot

    WHYnot

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    Apr 19, 2016
    Great thanks. I will try asking around the forum first to see if anyone is willing. :)
    Thanks a million for your assistance and advice. It is much appreciated.
     
  19. ramussons

    ramussons

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    Jun 10, 2014
    * Generate 5 clock streams. You will need 5 clocks if the clocks are random. Else you may be able to generate one from another.
    * User logic gates with a counter to select the required stream.
    * Using uP's may be over engineering.
     
  20. Herschel Peeler

    Herschel Peeler

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    66
    Feb 21, 2016
    Over engineering? Possibly. I was considering simplicity of manufacturing and of design alterations in the future.
    CMOS was my first consideration. Blinking once per second, twice, four and eight times per second would be easy. OP hasn't specified what frequencies he wants. He mentions another function was a battery charger. Perhaps blinking rate depends on battery charge.
    So maybe an LM339 to monitor battery voltage at four points. A CD4060 as an oscillator and frequency divider. An OC NAND gate on four selected outputs, enabled by the LM339.
    1 PPS for early charging. 8 PPS for fully charged. 2 or 4 for varying levels.
    I'm not certain if this was what the OP had in mind. In the final design both options would draw about the same current. In production the microcontroller would be smaller and cheaper board.
     
    Last edited: May 10, 2016
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