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Good Reliable Benchtop Power Supply?

Discussion in 'Power Electronics' started by Zerotolerance, Sep 20, 2011.

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  1. Zerotolerance

    Zerotolerance

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    Sep 19, 2011
    I am looking to buy a cheap, but good benchtop variable power supply to do small electronic repair such as tvs, stereos, and common househole appliances. Any suggestions are greatly appreciated.
     
  2. davelectronic

    davelectronic

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    Dec 13, 2010
    Bench top psu

    Hi there, welcome to the forum from me. Most electronics projects only require modest amounts of current, but some consumer electrical need a lot more than a few amps, its a tricky one, audio media and some viewing media products are lower on current, but bigger or motor, or high tension circuits require more power, prices vary, dependent on spec, voltage outputs control fine and course of current limiting, some good units out there, depends on your most used applications of the supply. Dave.
     
  3. jackorocko

    jackorocko

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    Apr 4, 2010
    One thing you might find useful, variac.
     
  4. Zerotolerance

    Zerotolerance

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    Sep 19, 2011
    Thanks for the welcome Dave. I am a complete amatuer when it comes to troubleshooting electronics. I do understand a bit of the basics of how things work and what not. I don't really even know where to start when it comes to repairs though. Just decided to pick this up as one of my many hobbies. Very interested in learning. I find it very self-rewarding to fix something that is complex or complicated such as circuits.

    All I will be doing is attempting to repair general household items such as tvs, stereos, alarm clocks, and other common household items. I am looking at 30v 5amp power supplies. Will this suffice for the work I will be doing and if so what is a good cheap brand?
     
    Last edited: Sep 20, 2011
  5. davelectronic

    davelectronic

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    Dec 13, 2010
    What bench top power supply

    Hi again Zerotolerance.
    I would say a bit more voltage, not a lot more but a bit, and current up to 10 amps, a variac is a handy thing to have, it gives you from the mains supply a variable AC voltage.

    To go out and buy a good quality supply is not cheap, for a lot of house hold electricals you can start with a modest PSU a lot of fix and repair of consumer electricals dont always require power to be applied from a supply, working on house electricals means at some point you might have to work on live mains powered circuits, yes its a dangerous procedure, but if good safe practices are followed, along with the correct tools its safe.

    I would learn the basics first, even before purchasing a power supply, the theory in books and on the internet will help you understand how circuits and components in them work, and behave under what is often very different circuits from one electrical product to the other.

    If you dont get a grip on the basic fundamentals you will not understand if when and why faults develop.
    To cut a long story short, i became ill, and what hobby's i had went out the window, scuba diving, shooting, firearms, fishing.

    Ive always had a fascination how things work, after becoming unwell a lot of the time i had to find a hobby that suited my changed life style, not my choice, yet i wanted a hobby, and i did it from scratch, it takes time, even now i am continuously learning, its a hobby / profession, you never stop learning as the electronics technology is constantly evolving.

    So the best advice i can give anyone new to electronics is start from the bottom with the basics, as you read up on electronic procedures your want to try them, this is in addition to repairing electricals, but always stay safe, electricity kills if your careless, ive had a few shocks at 240 volts by my own lack of care and attention, i was lucky to have not been killed, please never cut corners, and always follow safe working procedure.

    Start on low voltage small projects, you dont need a great vast tool kit to make a start, some of the projects might even become tools you can use in the following of electronics, dont try and jump in the deep end, all of us iam sure at some point, in are interest of electronics started with the basics, its knowledge you learn that will push you forward. Dave. :) PS the first books or media you read will give suggestions on what basic tools you can start with.
     
  6. daddles

    daddles

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    Jun 10, 2011
    I'd second Dave's suggestions to spend some more time learning stuff before you go out and buy a power supply. The first tools for troubleshooting are knowledge of how things are supposed to work and how to do practical troubleshooting. I'd then suggest that the first tool you'd want to buy would be a digital multimeter (DMM) or an analog VOM or VTVM. You'll next find that you probably want to buy another DMM/VOM because you often want to measure current and voltage at the same time or see how one voltage varies when another varies. Your second meter can be one of those cheap $3 Harbor Freight models. Or learn to make your own ammeters and voltmeters from some analog meters. My first VOM was a little cheap thing from Radio Shack that I bought in the 60's when I was in college and I fixed lots of things with that little meter.

    Once you get some experience under your belt, you'll have a better idea of what you need (and whether you think you really need a DC power supply). In the mean time, you can go to the second hand stores and pick up wall warts (where I live, they're typically 25 cents to $1 each) when you need a DC voltage. There are also lots of instructions on the web on how to build a decent DC power supply from a computer power supply. I'd suggest this as a much better way of getting a power supply. Besides costing nearly nothing, you'll learn some useful things along the way.
     
  7. Zerotolerance

    Zerotolerance

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    Sep 19, 2011
    I currently have a Fluke 863 and a Fluke 117. I use them for diagnosing A/C circuits. I am a Commercial Asst. Project Manager for a GC firm and when we have big electrical jobs I am pulled out of the office to assist the master electrician and all his journeymen. Just bought a Phillips 3335 Oscilloscope, a Weller WSD51 Soldering Station, and a Aoyue 852A++ Rework Station.

    My multimeters are top dollar meters especially my fluke 863. I like precise measurements when diagnosing things. I also have a cheap sperry ammeter but looking to and am looking to buy a nice fluke one here soon
     
    Last edited: Sep 20, 2011
  8. davelectronic

    davelectronic

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    Dec 13, 2010
    FLUKE

    Ever get the feeling you've been done up like a kipper, with tools of that spec your no novice / newbie to electronics, i must be gulable, hope it wont deter me from advising other newbies to electronics.

    No it wont, lots of genuine questions out there. Dave. :rolleyes:
     
  9. Zerotolerance

    Zerotolerance

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    Sep 19, 2011
    lol dave... I have experience with power distribution like commercial and residential wiring, but have no experience with "electronics" other than a little electronic kit I got from radioshack when I was in middle school that made like 100+ devices or whatever.

    I have good knowledge of electricity but not of "electronics".
    I have no knowledge of how to test circuits and narrow down what area is the problematic one. Or how to test using an oscilloscope or test components in circuit. etc.

    In other words if something is broke... I don't know where to begin to find the problem other than a visual inspection


    Here is my current setup. Oscilloscope coming thurs :)
    [​IMG]
     
  10. daddles

    daddles

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    Jun 10, 2011
    To get back to your original topic, why do you think you need a power supply for troubleshooting? I'm certainly not saying they're not useful and you'd never need one, but the examples of things you gave were line operated devices and I doubt you'd use a power supply often when troubleshooting them.

    If you can state what your needs are and especially what your budgeted amount is, we can help you with some power supply recommendations. I'll tell you about a few that I have.

    My favorite is my HP E3615A. This is a 20 volt 3 amp supply that has 10 turn pots for the current and voltage adjustments. I use it the most and got it used on ebay a number of years ago for $100 delivered. It was in new condition and was a steal.

    A few years ago I was able to trade someone for a B&K 9130 power supply for substantially under retail price. This is a triple output power supply and is an excellent power supply for a development engineer. It has three independent supplies in it. Two of them are 30 volts at 3 amps and one is 5 volts at 3 A. You can also set it up with the independent supplies in series or parallel operation for higher output voltages or current. It's also fully programmable via a serial port. If I could have only one power supply, this (or one like it) would probably be it. But it's a $900 supply and would probably be beyond most hobbyist's budgets.

    A few weeks ago an old friend gave me an HP 6033A power supply (he had 3 of them and didn't need all three) which is 20 V and 30 A output (but only capable of 200 W total). This supply fits my needs well, as I occasionally need higher currents at low voltages for testing things.

    I know you can buy fairly cheap power supplies made in China. These may in fact suit your needs well. Personally, I'd rather buy used HP power supplies on ebay.
     
  11. Zerotolerance

    Zerotolerance

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    Sep 19, 2011
    I also think I need one to test components that are taken away from the power supply that powers it. Such as electronic thermostats, etc.

    And for my future logic pulser or super probe :p
     
    Last edited: Sep 21, 2011
  12. davelectronic

    davelectronic

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    Dec 13, 2010
    bench power supply

    Hi again. I fix the odd home electrical item, other stuff i do are hobby projects, mainly power supply circuits, and bringing old CB radios back from the dead, and a bit of audio music electronics, i most enjoy modding stuff for use beyond its original intended purpose, my skills span 7 to 8 years, not long for a complex subject like electronics. i dont bread board projects, or pcb production, mainly copper strip board, i see a circuit and build it, after close study of the project. Dave.
     
  13. davelectronic

    davelectronic

    1,087
    12
    Dec 13, 2010
    Bench power supply

    What your looking to do, from your inital post is fault find and repair home electricals, so despite your electrical work and theory the same rules apply, you need to understand the theory behind component function, only literature and study of cicuit function and analysis can do this, often reinforced by practical work. Its how it starts with the theory of electricity, so you have a head start already. Study is the main driving force towards experience. Questions on the forum help as well. Dave.
     
  14. Zerotolerance

    Zerotolerance

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    Sep 19, 2011
    Thanks Dave. I have been reading a lot of literature lately on electronic components and testing/function
     
  15. poor mystic

    poor mystic

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    Apr 8, 2011
    We always most admired those techs who could find difficult faults with minimal test gear (say a damp finger). Of course caution is needed when testing high voltages with such equipment.
    The same philosophy led me to use computer power supplies, which can be had very cheaply, for most work. While it's nice to have a variable supply for those occasions when it is needed, those occasions have been uncommon in my experience.
     
  16. Zerotolerance

    Zerotolerance

    12
    0
    Sep 19, 2011
    Well then... Thanks everyone for the advice. I will probably just get a cheap $150 power supply since it is really not necessary. I really only would need one right now to power up my future logic pulser or superprobe I plan on building.

    I do have many Computer PSU's just laying around that I suppose I could use for their 12v, 3.3v, and 5v power
     
    Last edited: Sep 21, 2011
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