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Thread: 12v -> +8v, need some info

  1. #1
    g60
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    Post 12v -> +8v, need some info

    This my first time building anykind of powersupply, and was wondering if someone could tell me what parts I'm going to need for the power supply in this diagram http://www.earthlcd.com/cnt4lu4e.pdf .

    resitor, cap values? what's L1?

    [ 12-01-2001: Message edited by: g60 ]
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  2. #2
    g60
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    Any educated guesses?

    The data sheets for this screen say 150ma for the circut and 410ma for the inverter, can I use one powersupply for both?
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    L1 is going to be an Inductor (measured in uH - Henrys).

    If your only worried about the power section of the diagram check out www.National.com and search for the LM2595. They have a web-based power supply design that should be able to pick all the cap and resistor values for you. (i think you can find it on the stat sheet for IC, there will be a link for 'Live Simulation' and from thier you can tell it your requirements).

    Hope this helps,
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    If you're going to build a power supply, why not use one of the designs that we already have outlined here? We have a few different power supplies that will work, or you can just buy a premade one.

    Buying parts for the power supply is going to be expensive as well (~$60-80) so you might want to weigh your options before doing anything.
    IN DEVELOPMENT -- '96 Mustang, lilliput with PII/450 laptop, custom DC-DC power supply, 60GB; Garmin GPS; 802.11g; compact keyboard, small graphical LCDs, OBDII.

  5. #5
    g60
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    Does any one know another web based circut desinger? I can't get the national one to work.
    I went an electronics shop and the guy showed me a 3 prong thing (it was only about $3) that puts out 8v when a higher voltage is applied, am I going to fry something without useing the caps and resitors?
    >\\MP3G60//<

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    my guess would be that it is a linear regulator which takes your higher voltage and changes the excess into heat. (your difference is going to be about 5.8v (13.8 - 8) so as long as you dont need to much current there won't be to much heat put out. (maybe check the sheet of the chip in the diagram and see what the maximum current rating on it is).
    But hey for 3$ buy two hook one up to a computers powersupply and see what happened (just dont hook up your LCD till you know it works )
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  7. #7
    g60
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    Is voltage the only thing I have to worry about?
    I got the voltage regulators, '8v 1A positive'.
    The doc's say 150ma for the circuit, and 410ma for the backlight. Can I apply power useing only the voltage reg?

    Thanks for your help , I should have payed attention back in gr.11 electronics
    >\\MP3G60//<

  8. #8
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    looks like you'll be ok with the one regulator since you'll be drawing just over 1/2 an amp.
    Im don't think you'll even have to use a heat sink, although i'd check up on that if i where you (maybe a stats sheet for your reg?)
    [SIZE=1]'91 Nissan Stanza

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