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Advice on buying a power supply

  1. Feb 10, 2016 #1
    Hi Guys,
    I want a to buy a DC power supply to experiment with to power transistor amps that I want to build. I also I want to power up 12V car radios and other low voltage devices.
    I am looking at this one new from ebay which cost about $50.00.
    " 30V 5A Precision Variable Adjustable Digital DC Power Supply Regulated Lab Grade ".
    1.1 Input voltage : 220V/110V AC±10% 50HZ/60HZ±2HZ
    1.2 Line regulation: CV≤0.01%+1mV CC≤0.2%+1mA
    1.3 Load regulation: CV≤0.01%+3mV(I≤3A) CC≤0.2%+3mA(I≤3A) CV≤0.01%+5mV(I>3A) CC≤0.2%+5mA(I>3A)
    1.4 Ripple and noise: CV≤0.5mVr.m.s (I≤3A) CC≤3mAr.m.s (I≤3A) CV≤1.0mVr.m.s (I>3A) CC≤6mAr.m.s (I>3A)
    1.5 Protection: constant current and short-circuit protection
    1.6 Voltage indication accuracy: LED/LCD±1%+2digits, analogue display 2.5%
    1.7 Current indication accuracy: LED/LCD±2%+2digits, analogue display 2.5%
    1.8 Environment: 0 ~ +40 0C relative humidity:<90%

    Assuming that it actually works as stated above, is this the sort of power supply that would be useful for general electronic experiments. I don't have unlimited money to spend but I don't want to buy junk either. Please take a look at 1.4 Ripple and noise and tell me if this will be an issue.


  2. jcsd
  3. Feb 10, 2016 #2


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    hi ya Billy

    looks respectable spec's
    do you have a link to the ebay auction so we can have a look at the beast ?

  4. Feb 10, 2016 #3
    How Dee Dave,

    Here is the link http://www.ebay.com/sch/i.html?_fro...ower+supp.TRS0&_nkw=power+supply&_sacat=92074

    I also saw another one with more or less the same spec's that went up to 63V for about $75.00 So far all the "made in China" stuff I have acquired such as an Owan DS7102V scope has worked out OK so far.

    I would also like to have a high voltage supply say in the 100V to 1000V range to experiment with. I assume I can say such a thing on this forum...lol The mere mention of such experimenting has brought great hordes of safety police on other forums threatening immediate excommunication and banishment...lol


  5. Feb 11, 2016 #4


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    Sweet !!, might consider getting one myself !
    The saler is in my home town of Sydney, Australia

    wellllll .... LOL we like to know where people are at with their electronics experience etc before offering too much advice that may get them into further trouble
    Threads do regularly get closed because it becomes very obvious that the poster has no idea what he is dealing with
    It doesn't take too much effort to pick the experienced from the newbies :wink:

  6. Feb 11, 2016 #5
    Hi Dave,

    All joking aside, we all need to promote safety. I just finished repairing a 1934 RCA radio. When I got the radio I made a short video. The video was a test to see if I could even make a video and upload it to youtube. I don't have a nine year old kid to show me how to do such a thing...lol I was able to repair the radio without issue. The video, not so much...lol

    This is another power supply I was looking at (60V 5A Precision Variable Adjustable Digital Regulated DC Power Supply TS J8T8). Perhaps a bit more useful, not sure, as I have not looked at the spec's yet. The cost is $67.44 and free shipping, so not much difference in price. Here is the link.


    The reason for wanting any of these devices is related to being able to experiment mostly with audio amplifiers for guitars, both vacuum tube and solid state. Although poking around in valve amps is a relatively new endeavor, I have been repairing electronic devices all my life, or at least trying too...lol I made three solo trans Atlantic crossings in my sail boat. There are not many repair shops in the middle of the ocean so if it got fixed I had to do it myself. Being alone on a sail boat with a broken auto pilot will give one a large amount of motivation to figure out how to repair the bloody thing...lol


  7. Feb 11, 2016 #6

    jim hardy

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    For light duty breadboarding I buy "Wall Warts" in thrift stores for around $1

    feel them, the heavy ones are transformer based linear
    light ones are SMPS
    they're all marked as to output rating

    12 volt 1 amp ones are a treasure for such experimenting, you can power a breadboard directly
    sometimes you get lucky and find a 15 or 18 volt

    a particular treasure is old Hewlett-Packard transformer with 3 wire output 10-0-10 vac, a centertapped secondary good for ~ one amp
    that plus a bridge makes a dual supply, adding filters and building a tracking regulator is fun.

    30 volt ones for printers are plentiful
    i seldom use that much voltage but a pair would be handy for some higher voltage audio IC's like

    have fun on the cheap. As you hone your skills you'll get better at spotting a bargain .

    old jim
  8. Feb 11, 2016 #7


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    Planobilly - It says it has short circuit protection but does it also have an adjustable current limit? Sometimes that's handy.
  9. Feb 11, 2016 #8


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    yes it does look at the unit :smile:
    it has adj voltage and current

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