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Thread: 4,5 volt regulator

  1. #1

    Default 4,5 volt regulator

    Is there any way to build or purchase a 4.5 volt regulator?

  2. #2
    Flashaholic*
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    Default Re: 4,5 volt regulator

    Going to need more information here before I can suggest anything.

    1) Input voltage range?
    2) Crrent draw?
    3) Are you fine with a linear regulator, or do you want a switching regulator? The former will only step down the voltage and will lower the voltage by dissipating the extra power as heat, while the latter is generally larger and uses more components but more efficient.
    4) Size constraints?

    Oh, and welcome to CPF!
    Finning does help dissipate heat. This is why the fins are removed before cooking fish. Otherwise it will throw off the heat and not reach the proper cooking temperature. --Duglite

  3. #3
    Retired Administrator Norm's Avatar
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    Default Re: 4,5 volt regulator

    Quote Originally Posted by zapped View Post
    Is there any way to build or purchase a 4.5 volt regulator?
    LM317
    3-Terminal Adjustable Regulator

    Norm

  4. #4

    Default Re: 4,5 volt regulator

    well basically will be using this with two cr123 protected batteries so 7.2v's and need it to be small as possible....using it for an e-cigarette mod.

  5. #5
    Flashaholic*
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    Default Re: 4,5 volt regulator

    Without knowing anything about e-cigarettes, I take it that the device won't be drawing a lot of current? In that case I'd second Norm's suggestion of the LM317 or a similar regulator. Nice and compact, especially if you're happy working with SMD components.

    That said if it is drawing a lot of current I suppose I should let you know that it could get quite hot, which I suspect is one part of a normal cigarette you don't want to duplicate.
    Finning does help dissipate heat. This is why the fins are removed before cooking fish. Otherwise it will throw off the heat and not reach the proper cooking temperature. --Duglite

  6. #6

    Default Re: 4,5 volt regulator

    Thanks, am attempting to construct a commercial mod that's durable, not overpriced and small in size.Am more than a little electronically retarded so I might have to bother you guys for more technical help as I go about putting this together.

  7. #7
    Unenlightened JHM's Avatar
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    Default Re: 4,5 volt regulator

    Simple low power regulation can be achived with a single NPN transistor and a voltage reference, referred to as an emitter follower circuit.

    The voltage at the emitter of the transistor will be the same as the voltage applied to the base (minus about 0.7V)

    The wikipedia entry for "Linear regulator" has a good example (scroll down to "simple series regulator") where R2 is your load, you can also replace the zener diode with another resistor if your precision does not need to be high.

    I have built similar circuits, and have had good results up to a couple hundred miliamps, after that the regulation deteriorates, the transistor starts to complain,and it would be better to use a LM317 or other more complex (reliable) circuit

  8. #8
    Flashaholic COAST's Avatar
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    Default Re: 4,5 volt regulator

    Just go on radioshack.com and search "7805" That's a 5 volt regulator thats pretty small.
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  9. #9
    Thread Killer Illum's Avatar
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    Default Re: 4,5 volt regulator

    4.5 is not a common voltage for logic chips, its directly in the middle of 3.3/5
    A super simple way is to use 4.7V zeners you can pair with a LM7805....or use a high powered diode to drop 0.6V off of 5...that makes 4.4 but make sure the LM7805 is heatsinked. also, Linear regulators have a output-input differential of about 1.25V, meaning you cannot use the LM7805 to provide 5V if your input voltage is 6.3V or less
    besides, why 4.5V? if your thinking of 3AAA than I can tell you that under load those cells are probably around 3.5V

    Quote Originally Posted by JHM View Post
    Simple low power regulation can be achived with a single NPN transistor and a voltage reference, referred to as an emitter follower circuit.
    Heres a good read on emitter follower circuits, while its zener controlled series regulator but the concept is the same
    http://www.circuitstoday.com/zener-c...age-regulators
    I've built similar circuits for low current switches...should higher current applications be necessary one could always use it to switch a bigger transistor
    Last edited by Illum; 03-23-2010 at 07:37 AM.

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