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    [SOLVED]Closed: Re: Wiring of DC fans in Series

    True that I asked for a series connection however I might change my design to make it simpler and just use a buck converter. I am grateful for the responses guys and the dedication. This is part of...
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    [SOLVED]Closed: Re: Wiring of DC fans in Series

    Well since you mentioned that, I might actually need more then 2 fans, but I never mentioned this because I thought to keep them in pairs. A solution for 2 fans will work for 4 or 6 (at most).
    As...
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    [SOLVED]Closed: Re: Wiring of DC fans in Series

    Something like so? So the resistors are just a 15v potential divider that are turning on the transistors but what limits it to 15v?

    156070
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    [SOLVED]Closed: Re: Wiring of DC fans in Series

    I really like all the solutions with zeners and potential divider. I was thinking of using 15v fans because its half my supply however now its a different story. I have a bunch of fans I could use a...
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    [SOLVED]Closed: Re: Wiring of DC fans in Series

    Nothing is simple :D 7815 perhaps might solve the issue!
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    [SOLVED]Closed: Wiring of DC fans in Series

    Hi I have an enclosure with a 30vdc power supply inside.
    I would like to add some fans to keep things cooler inside however its much simpler to buy a 15vdc fan than a 30vdc fan.

    So I figured...
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    [SOLVED]Closed: Re: Driving an LCD using ShiftRegister

    Ok so clearly the LCD may be bust because I see nothing at all! :(

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    You were correct Sir! The LCD was bust! Thanks for the tip. It works like a charm
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    [SOLVED]Closed: Re: Driving an LCD using ShiftRegister

    Hi, Yes while I do agree that it is easy to misunderstand, I am using an existing library as in my first post and only changing the last 2 functions which instead of outputting bits directly to...
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    [SOLVED]Closed: Re: Driving an LCD using ShiftRegister

    I am using VisualMicro which allows me to debug however that's as far as I can go without some ideas. I send simple text and no characters show up.

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    Here's a suspicion. Could...
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    [SOLVED]Closed: Re: Driving an LCD using ShiftRegister

    To be fair I tried both MSB and LSB but to be fair im not sure
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    [SOLVED]Closed: Re: Driving an LCD using ShiftRegister

    Hi actually its a fully assembled circuit and im debugging with no success

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    no just the backlight lights up
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    [SOLVED]Closed: Re: Driving an LCD using ShiftRegister

    it is false yes just like the original source. it should technically be running as 8bit mode
    however the screen refuses to show anything
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    [SOLVED]Closed: Driving an LCD using ShiftRegister

    Hi, I am trying to control an LCD using a shift register. I am using the very successful arduino LiquidCrystal library which is tried and tested but am trying to modify the only function which...
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    Closed: Re: Driving 140x 3W LEDs

    Thanks for your reply. According to the LM317 the resistor determines the current given. So with this in mind, I'm thinking... if all the resistors are identical, shouldn't the LM317s (all 20 of...
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    Closed: Re: Driving 140x 3W LEDs

    Yes 700mA is the max of the LED so I could do a 2R and that will take the current down to 0.625A with a 5% tolerance the range will be from 0.595A up to 0.657A - so thanks for the tip
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    Closed: Re: Driving 140x 3W LEDs

    Ok so we are talking 20 of these circuits should do the trick. Assuming the 30VDC are clean, I should have 1.25v across R1, I should have any voltage between 3.2 and 3.6 on the leds and a constant...
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    Closed: Re: Driving 140x 3W LEDs

    Yes I get 'excited' too when I think about cooling but really my plan is based on another similar project of someone who already did it using 1W LEds. In 'his' project he used 12 LEDs for a smaller...
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    Closed: Re: Driving 140x 3W LEDs

    AHA that was the last bit I did not understand. Thanks very much Klaus so its possible! 1 or 2w is nothing. I was wrong thinking it was the complete voltage.... I should have known that.
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    Closed: Re: Driving 140x 3W LEDs

    Hi again, so a quick recap about the circuit, I bought the 140x leds with a forward voltage of 3.2v - 3.6v and a current of 700ma. There will be 70 on each side of the UV Exposure Box and will need...
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    Closed: Re: Driving 140x 3W LEDs

    Hi volker,

    Yes I did however I estimate for 140x leds I will need around 7 (not to mention that one string of 20 leds will be half on the bottom and half on top which is a problem since I want to...
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    Closed: Re: Driving 140x 3W LEDs

    Hi, Ok so I've been looking around and so far its not easy to get a constant current driver capable of taking more then 60v input though I did find ones which output 45A. This is not my situation....
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    Closed: Re: Driving 140x 3W LEDs

    This is really informative. I think if the voltage was around 230v I could just use a bridge rectifier and smoothing caps and work with mains, avoiding a powersupply altogether. I believe that a...
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    Closed: Re: Driving 140x 3W LEDs

    Hi, no objection at all. Im learning before I dive in.

    Wouldn't the pcb heat up a lot at 3 watts each?

    If I had to do all 70 in series, what voltage should it be?

    Finally how do you...
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    Closed: Re: Driving 140x 3W LEDs

    So would you say a constant current circuit would solve the problem of cheap leds?
    Ie: A circuit which allows 650mA to pass through to 7 or 14 LEDs in series?

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    The aluminum...
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    Closed: Re: Driving 140x 3W LEDs

    @Klaus - Hmm this is really interesting. I knew common LEDs worked with current but I assumed these were different. What I didn't realise was that they will drop different voltages across which will...
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