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homemade power conditioner?

Discussion in 'Electronic Basics' started by Joe, Apr 8, 2004.

  1. Joe

    Joe Guest

    I am in need of a power conditioner for my home recording studio. I was
    wondering if I could use some of the components I already have. I want to
    run my equipment off of an inverter, which would be connected to a 12volt
    battery, which would be constantly charged by a battery charger. Has anyone
    done this? Is it a logical way to get clean power?
     
  2. Probably not. The most important factor for an audio setup is that
    the line waveform have little high frequency distortion that might
    bleed through to audio signals and also a good, clean ground. The
    exact magnitude of line voltage is not very important. A good line
    filter or shielded isolation transformer with a clean downstream
    ground might be nice.

    A regulating transformer (Sola ferroresonant) might be good upstream
    of AC motor driven devices like tape drives and turn tables. But good
    quality motor driven devices do not depend on the line frequency or
    voltage, anyway.

    Inverters generally make high frequency noise that gets into signals
    and grounds.
     
  3. exray

    exray Guest

    Yikes! Unless the inverter has some excellent conditioning built in
    thats a VERY bad way to get power. The inverter output is full of
    spikes and the waveform will be poor.
    The best bang for the buck would be an old Sola type constant voltage
    transformer. No electronic components, no moving parts, good isolation,
    waveform will be good enough for modern electonics, etc. Big and heavy
    but no so much compared to a 12 volt battery and inverter.
    An outfit in Chicago? called Shape Electronics is a major manufacturer
    of these nowadays. You'd be hard pressed to damage one with a surge or
    have a spike get thru it.

    -Bill
     
  4. CJT

    CJT Guest

    That's how some UPSs work.

    The inverter output is full of
    You can't tell without details. Some are excellent, and others are
    poor. There may be a correlation with price.
     
  5. John Walton

    John Walton Guest

    Occasionally you will see Hewlett Packard (or now Agilent) A.C. power
    supplies on EBay -- there is a separate power supply section under test
    equipment.

    When I was in college we powered some of the "quiet room" physics equipment
    from an a.c. line which was driven by a MacIntosh tube amplifier. This gave
    a very quiet and regulated sine wave to drive some of the instrumentation.
     
  6. exray

    exray Guest

    No question about it. The OP was aking about homebrewing and if that
    was a logical approach.

    I'd stick with the constant voltage transformer.

    -Bill M
     
  7. Scott Dorsey

    Scott Dorsey Guest

    Why do you need a power conditioner? What is the problem you are trying
    to solve?

    Most inverters will produce MUCH worse waveforms than the power line, and
    you will have bigtime noise issues trying to run off of them. You can get
    some true sine wave inverters that have very low distortion, but they are
    not cheap or efficient.
    --scott
     
  8. Guest

    | In article <Io4dc.11301$>,
    |>I am in need of a power conditioner for my home recording studio. I was
    |>wondering if I could use some of the components I already have. I want to
    |>run my equipment off of an inverter, which would be connected to a 12volt
    |>battery, which would be constantly charged by a battery charger. Has anyone
    |>done this? Is it a logical way to get clean power?
    |
    | Why do you need a power conditioner? What is the problem you are trying
    | to solve?
    |
    | Most inverters will produce MUCH worse waveforms than the power line, and
    | you will have bigtime noise issues trying to run off of them. You can get
    | some true sine wave inverters that have very low distortion, but they are
    | not cheap or efficient.

    What would you recommend to get a nice clean pure sine wave, with no spikes
    or other high frequency hash, and is also locked tight to a frequency standard
    (unlike the utility power which has the liberty to tweak the frequency when
    demand is too high). This will need to also have backup capability, which
    might be for an extended period of time, which means a generator may be the
    source of power at times.

    Note: I'm not the original poster of this thread, but I have a similar
    interest.
     
  9. Todd H.

    Todd H. Guest

    Amen.

    Glad to hear this mentioned because not 10 seconds ago, I unplugged my
    laptop computer power to get rid of the annoying high pitched
    beeping-like subtle noise that I finally isolated as a ground loop
    that was coming through my computer speakers.

    My computer speakers are plugged into the wall and take 2 inputs--one
    from my PC running off an APC Back Ups Pro UPS, and the other from the
    laptop which is plugged into the wall. While plugging all 3 in the
    UPS doesn't seem to fix it (likely due to a peripheral hanging off the
    PC plugged into the wall), unplugging either one of the PC's audio to
    the speakers fixes it, or unplugging power from the laptop does the
    trick too.

    Anyone know of any place selling 1/8" stereo inline isolation
    transformers?

    Best Regards,
     
  10. Well, Radio Scrap has (or had) an isolation transformer for auto apps,
    which should also work in this case. But it seems to me that it would
    be better to isolate the actual noise, which might be coming from the
    wall wart or power brick that charges your laptop battery.

    You might try putting a big electrolytic, like a 4700 uF, across the
    power from the batt charger. Just to see what happens.
     
  11. Scott Dorsey

    Scott Dorsey Guest

    What kind of load, and why do you need frequency stability? For most
    equipment, frequency stability is a non-issue.

    I can recommend the Best and Liebert online UPS systems. The 12KVA and
    larger units can be slaved to an external reference oscillator if you
    really need stability, and they can be specified to under 2% line distortion.
    The Invensys BPIII Industrial is a good choice if you need more than 100 KVA.

    If you need better than 2% distortion and only have small loads, Abacus
    Controls, KGS Electronics, and Industrial Test Equipment, Inc. all make
    stabilized AC supplies. Count on closer to $10/watt, though, as opposed
    to around $1/watt for the cheaper Best and Liebert gear.

    We replaced our 400 Hz motor-generator set systems with a bunch of the
    smaller Abacus Controls boxes, and they are phenomenally more convenient.
    No poking, no prodding, no calling down to the basement to fire the converter
    up in the morning.
    --scott
     
  12. Wow, that's a lot of requirements, I'd revisit them first to see if
    what I was trying to do could be done in a more economical fashion.
    In a brute-force kinda world, you'd end up with one of the HP AC
    sources that John was talking about, running off a separate UPS, with
    a backup generator, but that's a whole ton of money compared to (for
    instance) running your device off batteries and using a real frequency
    standard for the parts that care about that.
     
  13. WalMart has them for cars, so you'll need Phono-to-headphone adapters.
    Worked wonders for fixing the ground loop problem my iPod had with my
    AUX input in my car...
     
  14. This sounds like a great waste of energy, both human and electrical.
    Is your AC line really that bad? Professional audio equipment works
    just fine with normal power company AC power.

    The only thing I'd recommend is using a UPS if you'll operate a DAW
    and you don't want to deal with short outages and glitches. The APC
    SmartUPS sine wave output models are pretty good for this use. I bill
    out time on my rig, and having a UPS prevents downtime, which saves
    everyone.

    Aside from that, the power conditioning setup you describe sounds like
    a potentially dangerous, expensive waste of time, energy and money.
    Unless of course, you have some real problem with utility power that
    I'd be interested in hearing about so we can suggest a workable
    solution.


    Regards,

    Monte McGuire
     
  15.  
  16. Arny Krueger

    Arny Krueger Guest

    First make sure that you have bad power. This device will give you a number
    of objective clues:

    http://www.smarthome.com/9034.html
     
  17. With the frequency requirement, you're basically looking at a double conversion online UPS--whether prepackaged or soemthing you piece together.

    Toshiba makes excellent medium-sized UPSs with low distortion output http://www.tic.toshiba.com/productgroups.php?family=UPS
    Oneac makes smaller units that are also very clean http://www.oneac.com/pdf/917161b1.pdf

    Exeltech makes low distortion inverters as small as 125 Watts and for a wide range of DC inputs http://www.exeltech.com/ If you need very long runtime, it can be much cheaper to build your own solution with telecom batteries and charging plus one of these.
     
  18. They do the job and at a very reasonable price, but their output waveform is still pretty noisy. Stick a 'scope across the line and yank the plug sometime...

    Best and Oneac both make small UPSes with clean outputs.
     
  19. Scott Dorsey

    Scott Dorsey Guest

    If you have a ferroresonant transformer there, you don't really need a good
    waveform on the input, but you do need pretty good frequency regulation.
    You can also live with dropouts as a result, too, so you can probably get
    away with a cheaper standby UPS without any trouble.

    Somebody has nicked the BEST catalogue from my office and I don't remember
    the name of their line of cheap standby UPS systems without isolation.
    It's one line below the Ferrups stuff. I think that's about where you should
    be looking because it's no sense spending money for capability you don't need.
    You should make sure that it will be happy driving the ferroresonant
    transformer, though, which will be a weird load. Get the power factor off
    the PBX supply and make sure the UPS is reated for it.

    I've had some bad experiences with the APC stuff and had some trouble
    getting APC to make good on their guarantees.

    Most of the other stuff I am familiar with are online systems, which you
    really don't need.

    Have you considered just floating a 48V battery off the rails? It would
    seem a lot cheaper to just provide the battery backup on the 48V side
    rather than on the AC input. You might want to check Power Conversion
    Products at www.pcp.com for telco power stuff.
    --scott
     
  20. With the FRT, you won't need super-low distortion AC and you won't need zero-dropout switching, so a standby UPS would probably work fine.

    Why not just replace or augment the -48V system with something bigger & newer? You wouldn't believe how much -48V overstock and surplus stuff out there from the dotbomb & telecom busts.

    Where are you located? I can probably find you a turnkey solution from a bonded vendor if you want...
     
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