Adjustable DC power supply

Discussion in 'General Electronics Chat' started by AKnogood, Nov 25, 2013.

  1. AKnogood

    Thread Starter New Member

    Nov 21, 2013
    17
    0
    Do you guys have an adjustable DC power supply for your home projects? Did you buy or build one?

    I was looking at these 2 models on Ebay and would like to know what you think:

    Model 1
    Model 2

    Or would you have any other models to suggest? Thanks!
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,507
    2,367
    I built mine many years ago, but those look reasonable for a starter supply for the price.
    Max.
     
    #12 likes this.
  3. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    :rolleyes: You'd be hard-pressed to build one for less...
     
    absf, ErnieM and #12 like this.
  4. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
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    I built a 60V, 10 Amps supply (peak 100V at lower currents, inrush current much higher).

    Without the supply transformer, for about 30 dollars or 40 dollars (it needs cooling fans, a 12V AUX supply, heavy cables, good capacitors, even a heatsink for the rectifier).

    TL494 + large VGA cooler + 2 large toroid coils.

    I tested a welding transformer and a big toroid as transformers.
    I have done a permanent test for 3 months.

    The MOSFET can latch at the upper end, but is exchangeable with a PNP.

    It is not short circuit proof this would mean slightly higher cost.
     
  5. ScottWang

    Moderator

    Aug 23, 2012
    4,852
    767
    The Mode 2 would be better, because the voltage of mode 1 is too less, but that's depends on what do you do for your experiment, if you say something about what you need to do, maybe it's more easier to give you the suggestion.

    I bought the kits from the begining that I started to learn the EE, and I also built the very simple power and like this Two 4 kinds ±5~15V fixed power, it's easy to use, this power can't adjust the voltage, but I have some others can.
     
  6. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    Laptop power supply + hacked 12v/35v booster PCB (80 volts are possible with different MOSFET/flyback diode + high voltage capacitor).

    It is cheap, useful when you don't need current adjustment (most circuits or real world applications don't have a current regulated supply, except flat panels, TV sets and the like).

    I mean it is not needed all to often except for physics lessons in college (opinion). I was always able to do without it.

    If you want to regulate currents, it is almost always only smaller currents.
     
  7. #12

    Expert

    Nov 30, 2010
    16,252
    6,749
    For most of us, building a power supply is child's play, but two of the "Model 1" supplies would do most of my work, and can not be had for a better price, even if you build them yourself.

    I'm serious. If I need 400 VDC, I have a rig for that. If I need 10 amps at 0V to 15 volts, I have a rig for that. +/- 15 with both voltage and current adjustable does more than 90% of what I need.
     
  8. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    My favorite supply gives me 5V at a fwe amps, and a 30 V +/- supply at an amp perhaps. All are voltage adjustable with a max current limit set. I've got three I believe, one is even programmable (IEEE-488).

    That said, in the past year I've used my 9V wall wart the most. My point is you will never go wrong with a quality lab supply you can depend on 100%
     
  9. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
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    yes but if you relocate, you need to dump it as ewaste or as donation somewhere, or to pay a lot of $$$ for transportation costs.

    If you are a student and then have accumulated a lot of gear.

    These metal shells can last 1000s of years so if you intend to move, add the cost of disposing or transportation.

    I made some experiments with power electronics but the welding transformer was easy to get rid of- as good as new.

    It is not guaranteed you can get rid of a big power supply quick somewhere out there.

    Still having a bag with loads of cables here. It's quite hard to carry through the airport I guess.
     
  10. #12

    Expert

    Nov 30, 2010
    16,252
    6,749
    I wonder who takao is talking to...:confused:
     
  11. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
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    Do you guys have an adjustable DC power supply for your home projects? Did you buy or build one?

    I have been ridiculed by maybe 50 power supplies, wall adapters, and more than 100 cables all incompatible, just within a few years.

    I saw (at a workshop) bags full of old wall adapters and power supplies, really loads of them.

    I could even post a picture from Ghana where you see people actually dismantling the transformers.

    I have an habit to write my opinion in support of a greater cause.

    So here is the counter question to OP:

    How long do you plan to keep the power supply?
    Do you need it immediately for a purpose?
    Will you need a different one soon?

    Most my experiments can run from USB or batteries or a laptop adapter.
     
  12. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
    1,190
    156
    For what it came down to was price .. I could buy a almost brand new 30V 3amp power that works and has safety features built in for alot cheaper than I could build one and alot less headaches ... Personal I would buy one and then if you want to build one then go ahead but at least you have a working supply ..
    Check out mastech power supplies
     
  13. Jaguarjoe

    Active Member

    Apr 7, 2010
    770
    90
    FWIW- MPJA (Marlin P. Jones & Assoc) sells similar units for similar prices.
     
  14. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    Look good, but you might want to get a dual output unit with lower amperage (like 0-20V, 2A dual) because there are so many cases where you will need dual outputs.

    We used these at work:

    http://www.ebay.com/itm/Regulated-D...706?pt=LH_DefaultDomain_0&hash=item27db5120fa


    similar:

    http://www.ebay.com/itm/MASTECH-HY3...328?pt=LH_DefaultDomain_0&hash=item3385fec0d0


    A pair of these cost less than $100 and would get most jobs done:

    http://www.ebay.com/itm/MASTECH-HY1...221?pt=LH_DefaultDomain_0&hash=item2ecc0b7b9d
     
    Last edited: Nov 27, 2013
  15. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    +1 You can't possibly build for what is available to buy these days.
     
  16. Metalmann

    Active Member

    Dec 8, 2012
    700
    223


    I bought one identical to #2, and it works fantastic.
     
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