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How Do I regulate 3v DC?

Discussion in 'General Electronics Discussion' started by The Merry Yeoman, Mar 8, 2016.

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  1. The Merry Yeoman

    The Merry Yeoman

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    Mar 8, 2016
    I am trying to remove the need for replacing batteries in a component that is but a part of a larger project. The device is recognizing the lack of voltage stability as powering on and off. My meter reads 2.8 "something" to 3.1 "something" and back repeatedly. I am (of course) getting this reading from the AC adapter that I am trying to replace the batteries with. It is a multi use (universal) adapter set at it's lowest setting which is 3v. I am told a capacitor may be the answer as raising the voltage and lowering it with resistance is already taking place in such an adapter.
    I am completely new as this is my first project and would, at this juncture, appreciate the simplest solution (ie a component or other device in - line) rather than a major learning experience unless completely necessary. I have embarked on more than expected already. Thank you in advance for *ANYONE'S* help!
     
  2. cjdelphi

    cjdelphi

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    Oct 26, 2011
    What is? What's the current load?

    Can't see what you can....
     
  3. Gryd3

    Gryd3

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    Jun 25, 2014
    You need to tell us or take pictures with more details.
    There are AC and DC supplies. Tell us what the output is.
    Tell us what you are trying to power. The only reason a voltage would change like that is if you were stressing out the supply by pulling too much current.
    A capacitor may slow-down the change in DC voltage just enough, but it won't prevent the voltage from changing! (Think of it like a reservoir... a very tiny one. It drains quickly and is only suitable for very sudden changes. You can go overboard and buy a huge one, but if you are drawing more current then the supply can handle, even the biggest capacitor in the world won't help.)
     
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  4. The Merry Yeoman

    The Merry Yeoman

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    Mar 8, 2016
    I don't know what the load is or how it is measurable.
    I am using a universal AC to DC adapter set at 3v -It can go up to 12v but I am replacing two AAA batteries for a simulated equalizer that is designed for a t-shirt warn in a dance club (originally). I will leave it at 3v unless there is a way to lower it as I stabilize it. The adapter says 600 mA.
    When I figured out why the device was powering on and off, the device was not attached. It was during my diagnostics when I hooked it up to my multi-meter to read DC voltage.
    So is a capacitor a bad idea if it isn't drawing too much current? -If not, what kind of capacitor might work?
    Let me know if there is more detail needed in order to help solve this problem. Thanks again.
     
  5. cjdelphi

    cjdelphi

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    Oct 26, 2011
    It's normal for the voltage to drop like that under heavy current draw, but these tshirts run on aaa's so i can't imagine it being more than the adapter

    So maybe your adapter is faulty or the tshirt is causing a short? Ideally you need to measure the current draw with a multimeter
     
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  6. Gryd3

    Gryd3

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    Jun 25, 2014
    Can you please tell us the rest of the numbers on the adaptor? They should have an 'mA' rating as well.
    This would be a huge clue into what might be happening
     
  7. Martaine2005

    Martaine2005

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    May 12, 2015
    :p

    Martin
     
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  8. The Merry Yeoman

    The Merry Yeoman

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    Mar 8, 2016
    I measured the voltage without the device hooked up. Incidentally, there isn't actually a t-shirt involved. When the device is hooked up it seems to mimic such fluctuation as it powers on and off repeatedly.
    How do I measure current while hooked up... with the DCv setting on my meter? is current measured in voltage?
    Once I understand I can get a reading while it's hooked up to the batteries to see what it should say as well.
    Also, I thought about it being the adapter so I changed adapters but not brands. Supplies of such are limited in my town. It is a Powerline MULTI-USE AC ADAPTER 3-12 Volts/600 mA "2X THE POWER! OF A 300MA ADAPTER" "The Perfect Replacement for Batteries or Lost Power Supplies"
    Thanks again
     
  9. Martaine2005

    Martaine2005

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    May 12, 2015
    Put your meter in series with the circuit.
    [​IMG]
    Martin
     
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  10. The Merry Yeoman

    The Merry Yeoman

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    Mar 8, 2016
    Would it be accurate to hook up to the battery terminals? -I don't know what order would simulate this exactly on this device. What does DCA stand for on this meter cartoon? Are we measuring amps?
     
  11. BobK

    BobK

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    Jan 5, 2010
    DCA -> Direct Current Amps

    The meter probes have to be in series with the battery. If physically possible, have the battery part way out of the holder so that only the negative (flat) side of the battery is making contact. Then connect the red probe to the positive contact on the battery and the black probe to the positive contact on the battery holder.

    Bob
     
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  12. Alec_t

    Alec_t

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    Jul 7, 2015
    If we assume the 'equaliser' has some electronics which are sensitive to supply voltage ripple then a smoothing capacitor external to the AC/DC adapter may well help. You could try, say, 470uF (rated for >20V in case the supply gets inadvertently switched to its maximum voltage setting).
     
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  13. The Merry Yeoman

    The Merry Yeoman

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    Mar 8, 2016
    Bob,
    I have Attempted this with meter set on all of the A settings (20A,mA,μA) marked AC/DC and didn't see anything readable. A couple of numbers may have flashed when I accidentally made contact... I don't have a clue if I am on the right settings or if I'm looking for amps?... or remotely what numbers to look for or truthfully... the reason I need to know the current is evading me when I'm pretty sure the reason is that it could be too much current...?
    Is this (2 AAA) t-shirt device suspect of pulling too much current for my adapter... really?
    I will reiterate...
    I am new and would, at this juncture, appreciate the simplest solution rather than a learning experience unless necessary. I have embarked on more than expected already.
    Not to sound silly but due to time constraints if someone told me that placing an old VCR in series would solve my problem I could use the one in my basement right now.
    Thanks for your understanding and I really do invite the learning experience if necessary.
    Alec, I will try your idea if I don't find the solution before being able to get to micro center (45 mins away). -Unless of course an old VCR has a 470uF capacitor in it somewhere!o_O
     
  14. Alec_t

    Alec_t

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    Jul 7, 2015
    The problem with a 470uF from an old VCR is that the 470uF will be old, too. Old electrolytic caps are likely to have deteriorated, so may not work well. But give it a try anyway ;).
     
  15. BobK

    BobK

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    Jan 5, 2010
    mA would be the right setting.

    If your meter has a separate jack for the positive probe for Amps, you would use that only on the A setting, not the mA setting. Perhaps this is why you are not getting a reading.

    Bob
     
  16. Gryd3

    Gryd3

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    Jun 25, 2014
    I understand the frustration, but the learning process here is required here.
    If not for yourself, you need to know or be able to do just enough to provide us with the details we require to actually help.

    If the device constantly pulls too much current, you need a more capable adaptor.
    If the device spikes and draws too much current momentarily, then a capacitor may help... but this depends on how long the 'spike' is as well as the draw during the 'spike'."

    FYI, a AAA battery can supply up to an 1000mA, which is much higher than your adaptor is capable of. (The will not last long in this case, but they *can* do it.)
     
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  17. The Merry Yeoman

    The Merry Yeoman

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    Mar 8, 2016
    Ok... this is what I'm talking about. You allude to the distinct possibility that there is a more capable adapter. If there is one that is special enough to help overcome such, I would like to know where to get it.
    I do know from experience that I have managed to make devices tethered to a power supply that would have otherwise required undue maintenance of replacing batteries (that I don't need to be portable).
    Disclaimer: I am a lifelong learner. It frustrates me that I don't have the time to put into this as a learning experience more than you may know. However, I am currently farming (spring cleaning stalls), working (including overtime hours) at the local factory, renovating my house with 5 people living in it, moving my workshop across town, Trying to do this project, and my wife is filling in for her work's owners while on a trip (3 kids).
    Just one of those moments, ya know?
    So what I'm saying is: I appreciate your patience with my ignorance .
    And allowing me to vent.:)
     
  18. Gryd3

    Gryd3

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    Jun 25, 2014
    Well.. above you stated the rating on the adaptor was 600mA.
    Take a look in a junk drawer or stores for an adaptor of the same voltage that offers more mA...
    The tricky part though, is that without being able to use the meter to actually measure it, you are guessing.
    This sounds like the most likely cause/solution, but without verifying you could be wasting more time and $$$.
    Can you describe what the device is you are trying to power? You are absolutely sure the batteries are in series to provide 3V, and not in parallel to provide 1.5V as a higher amperage?
    Do the batteries fit back to back, or side-by-side? (Sometimes, but very rarely, side-by-side sometimes 'taps' a wire to the middle of the batteries. This allows the device access to a + 1.5V and a - 1.5V source. Pictures are worth a thousand words if you cant describe it)
     
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  19. The Merry Yeoman

    The Merry Yeoman

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    Mar 8, 2016
    When I was in the device (a simulated 'equalizer' meant for a t-shirt) It had a red wire going to the positive terminal and black going to the negative. The two AAA's were to be opposite positions. and the other side (opposite the terminals was just your classic strip of metal to link them in series.
     
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  20. cjdelphi

    cjdelphi

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    Oct 26, 2011

    Sounds like you blew the fuse in the meter..

    If it has a 10amp range, you have to pull one of the probes move it to another socket, set in ma, did you try to measure the current by touching positive and negative?

    If so, no ... connect the negative of the battery, the negative pushed against black probe, then your red probe to the + of your battery...

    If no 10amp, replace the popped 200ma fuse (or whatever)
     
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