Page 4 of 6 FirstFirst 123456 LastLast
Results 31 to 40 of 60

Thread: you dont necessarily need a voltage regulated PSU

  1. #31
    Maximum Bitrate
    Join Date
    Jul 2004
    Posts
    574
    Quote Originally Posted by justICE
    I am also confused how the +12V can be a "smooth 12V". Is this only when the car is off? The alternator does not charge at 12V. If the the alternator is connected to the battery, which is connected to the PS it will also be at the alternator potential.
    I have the same question...if the "wheelchair" battery is connected to the alternator which is outputting differing voltages, won't the PS be recieving the same voltages?

  2. #32
    FLAC
    Join Date
    Sep 2004
    Posts
    1,577
    From www.minibox.com
    Q: Does this take a 12V input (like from a car), what's the minimum operating voltage, and what kind of connections does it come with?

    A: Cars are nasty operating environments, so while you may use this power supply in a car, we do not recommend it as it will void your warranty. Read below for more information, including the timeline for the release of M1-ATX vehicle power supply.

    Q) Can I use this DC-DC converter with a lead acid battery?
    A) Lead acid batteries can produce 14.4V when fully charged.
    Our DC-DC converter was designed for 12V operation, however, it will work
    at 14.4V without any problems. You can also put 2 diodes in series with the
    DC-DC converter to drop the voltage by 1.5V or so. Radio Shack sells them for
    $0.5. Please read below for more info.

    Q) What is the voltage operating range of the PW-60/70?
    A) 10.5-15.5V. Below or above these voltages undervoltage/overvoltage protection will shut down the power. The boards cannot be damaged unless you apply more than 24V.

    Q) How long will my mini-itx last from a lead-acid battery?
    A) We tested a EPIA-800 board with a small 12V 7AH battery and we were
    able to keep the system up for 10-12hous. With a regular car battery you
    could power the system (without recharging) for about 1 week.

    Q) Can I use this DC-DC converter in a car?
    A) Cars can be nasty environments. If the voltage will be in between 12-14.8,
    things will be fine. However, cars can produce anywhere from 5-18V,
    especially when using a weak battery. Again, few diodes should drop
    V(in) by 1-2 volts, but please make sure you have a good battery!

    You can use the ITPS (power sequencer and regulator) to further regulate and control your computer power ON/OFF features in a car environment. Also, by end of 2004, we will have the M1-ATX, a DC-DC converter + power sequencer that operates from 6-30V while providing strict voltage regulation on all power rails!
    The M1-ATX sounds very intriguing. I might even delay my project for a 1-stop solution. I was intending to hook up a 0.8Ah or possibly 5.1Ah sealed lead acid battery ($3 and $10 respectively) but maybe the M1-ATX will be sufficient. It depends a bit on wattage - I'll be running a micro ATX board so will need a lot of wattage.

  3. #33
    Jesus Freak antimatter's Avatar
    Join Date
    Jan 2004
    Location
    California
    Posts
    4,545
    Quote Originally Posted by Jackboot
    I have the same question...if the "wheelchair" battery is connected to the alternator which is outputting differing voltages, won't the PS be recieving the same voltages?
    It appears that he has some sort circuitry that isolates the battery charges it.

    Would you care to explain this more
    -Jesus- King of Kings Lord of Lords

  4. #34
    FLAC
    Join Date
    Sep 2004
    Posts
    1,577
    Doesn't the alternator output around 14.4V? If so, my quote above answers that?

  5. #35
    Deactivated Diewlay Lowmo's Avatar
    Join Date
    Aug 2004
    Posts
    103
    Smoke and mirrors? Someone care to elaborate, please?

    Perhaps older cars have this magical "isolated" circuit.
    My car was made in '02.

  6. #36
    Variable Bitrate blurp's Avatar
    Join Date
    Sep 2003
    Location
    Hampshire, TN
    Posts
    349
    Quote Originally Posted by Diewlay Lowmo
    Smoke and mirrors? Someone care to elaborate, please?
    from dictionary.com:


    smoke and mirrors

    n. Marketing deceptions. The term is
    mainstream in this general sense. Among hackers it's strongly
    associated with bogus demos and crocked benchmarks (see also
    MIPS, machoflops). "They claim their new box cranks 50 MIPS for
    under $5000, but didn't specify the instruction mix -- sounds like
    smoke and mirrors to me." The phrase, popularized by newspaper
    columnist Jimmy Breslin c.1975, has been said to derive from carnie
    slang for magic acts and `freak show' displays that depend on
    `trompe l'oeil' effects, but also calls to mind the fierce Aztec god
    Tezcatlipoca (lit. "Smoking Mirror") for whom the hearts of huge
    numbers of human sacrificial victims were regularly cut out. Upon
    hearing about a rigged demo or yet another round of fantasy-based
    marketing promises, hackers often feel analogously disheartened.
    www.bradleyjacobs.com

    There is more stupidity than hydrogen in the universe, and it has a longer shelf life. -- Frank Zappa

  7. #37
    Low Bitrate
    Join Date
    Sep 2004
    Posts
    68
    Quote Originally Posted by Arathranar
    Doesn't the alternator output around 14.4V? If so, my quote above answers that?

    Not sure which quote you are referring too so I address each seperately:


    Quote Originally Posted by Arathranar
    Q) Can I use this DC-DC converter with a lead acid battery?
    A) Lead acid batteries can produce 14.4V when fully charged.
    Our DC-DC converter was designed for 12V operation, however, it will work
    at 14.4V without any problems. You can also put 2 diodes in series with the
    DC-DC converter to drop the voltage by 1.5V or so. Radio Shack sells them for
    $0.5. Please read below for more info.
    True they can produce 14.4V when charged (or charging). Putting two diodes in front of the original posters PSU will cause a problem when the car is off. He would then have ~10.5V.

    Quote Originally Posted by Arathranar
    Q) What is the voltage operating range of the PW-60/70?
    A) 10.5-15.5V. Below or above these voltages undervoltage/overvoltage protection will shut down the power. The boards cannot be damaged unless you apply more than 24V.
    Does not apply to regulating 12V for the original posters setup.

    Quote Originally Posted by Arathranar
    Q) How long will my mini-itx last from a lead-acid battery?
    A) We tested a EPIA-800 board with a small 12V 7AH battery and we were
    able to keep the system up for 10-12hous. With a regular car battery you
    could power the system (without recharging) for about 1 week.
    Does not apply.

    Quote Originally Posted by Arathranar
    Q) Can I use this DC-DC converter in a car?
    A) Cars can be nasty environments. If the voltage will be in between 12-14.8,
    things will be fine. However, cars can produce anywhere from 5-18V,
    especially when using a weak battery. Again, few diodes should drop
    V(in) by 1-2 volts, but please make sure you have a good battery!
    Again, if you are using diodes to "regulate" power then there will be problems when the alternator is not charging.

    Quote Originally Posted by Arathranar
    You can use the ITPS (power sequencer and regulator) to further regulate and control your computer power ON/OFF features in a car environment. Also, by end of 2004, we will have the M1-ATX, a DC-DC converter + power sequencer that operates from 6-30V while providing strict voltage regulation on all power rails!
    Now we are getting somewhere. This sounds great IF this m1-atx provides decent power (like more then 5A on the 12V rail for instance). Otherwise, there are already alternatives available.

  8. #38
    FLAC
    Join Date
    Sep 2004
    Posts
    1,577
    Quote Originally Posted by justICE
    Now we are getting somewhere. This sounds great IF this m1-atx provides decent power (like more then 5A on the 12V rail for instance). Otherwise, there are already alternatives available.
    Unfortunately not - only 3 amps. I emailed to ask.

    The part of the quote I meant was the bit about 14.4V being fine. The rest was all potentially interesting info that wasn't directly relevant.

  9. #39
    Low Bitrate
    Join Date
    Sep 2004
    Posts
    68
    Quote Originally Posted by Arathranar
    Unfortunately not - only 3 amps. I emailed to ask.

    The part of the quote I meant was the bit about 14.4V being fine. The rest was all potentially interesting info that wasn't directly relevant.
    Hopefully sooner then later there will be more companies producing PS's for the auto. The cost is too high when there is only 1 really good option=(.

  10. #40
    FLAC
    Join Date
    Sep 2004
    Posts
    1,577
    Ok. I'm confused. A local computer surplus store has sealed lead acid 7.2Ah batteries for $10. They have some details about standby use and cycled use. What is that? One of those (can't remember which - cycled I think though) had a max current limit - 0.2A I think it was. The other didn't. I'm intending to run a micro ATX m/b with an AMD2500+ so I expect my wattage to be high. So I'm going to get one of the 200W dc-dc psu's from mini-box. 200w/12V ~= 16A which is a lot of current (but nicely allows for a 15A fuse assuming I don't quite need the full 200W).

    So I hook this battery up with a diode from the alternater or from a 12V line of sufficient gauge this side of the firewall (if I can find that - what gauge wire would I need to hook into to allow 15A of current!).

    I've read on the forums that if you do the USB +5V mod, the standby current draw can be as low as 7mA. A 7.2Ah battery would therefore let me leave the car off with the computer in standby for about 43 days. That seems sufficient safety margin to avoid running the car battery down

    The problem is - if I hook this up to the alternater, it'll only get juice when the car is running. So when I switch off the car, the battery will take over as the current source for the pc as I trigger a standby via a relay. Can this battery supply the amps I need during the shutdown timeframe?

    And that'll be a big drain (the battery would last less than 1/2 an hour if running the pc alone) so it'll need topping up the next time it runs. Will the alternater's output at ~14V be sufficient to charge this battery and power the PC? Will it overcharge the battery if I go on a long trip.

    So many questions

Page 4 of 6 FirstFirst 123456 LastLast

Similar Threads

  1. Frequently Asked Questions
    By bgoodman in forum The FAQ Emporium
    Replies: 33
    Last Post: 05-03-2005, 06:25 PM
  2. setting up a regulated psu
    By RogerWilco in forum Newbie
    Replies: 1
    Last Post: 08-21-2004, 06:12 PM
  3. What to look for in a PSU some info for you
    By cproaudio in forum Power Supplies
    Replies: 9
    Last Post: 04-04-2003, 01:07 AM
  4. 12v/5v regulated psu?
    By etrik in forum Power Supplies
    Replies: 2
    Last Post: 08-12-2002, 03:00 AM
  5. need negative voltage to power PSU
    By l4tran in forum Power Supplies
    Replies: 2
    Last Post: 05-11-2002, 09:40 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •