I'm not impressed by Korad .... i would choose any reputable brand well before that one, and if you don't find a dual one, buy two identical models,
if it's the case you'll have to fiddle, serial and parallel mode ..
Some Mastech and clones had better reliability in the past
Do note, you pay cheap, you'll get cheap
I have 2 Korad KA3005P. For what I do I cannot complain.Quote
Having two of ANY electronics is invaluable, if,and when, one of them develops any problems. Open them both and measurements throughout the good one can be compared to the one that is malfunctioning.
I have bought several used Power Designs, one HP, and one Lambda supply, and had pretty good luck with all of them.
The HP needed the most attention - the power switch crumbled; the smoke came when I turned it OFF! Confusing. Not a typical fail, I think. It also has old stiff wiring that needs replacing.
The PD's just seem to work; I love them, and would like more, just because I like 'em, not because I need 'em!
There are several dual and triple versions, e.g. the TW4005 is a twin 40 volt 0.5 amp model. I don't have one but want one. I have a 6050, single output 60 volts or 5 amps, but not both at the same time!
The Precision models, always with those nice four-digit dials, are probably about an order of magnitude more precise. Single output. Specs are 100uV noise and regulation and such; I usually see around 10uV or less, including watching the oven heater switch on and off. (Newer models used LM399.)
The precision models are good enough that you start expecting them to be a reference; not to metrology standards, but sub-millivolt easily.
Quality... well, I guess... the designs came out of the same brain, but for different purposes. They're all nice.
All the PD's are old, no doubt. A little control cleaning might be in order; I keep thinking I should do that someday. Mine just work, except some of the meters. Which I should fix someday, but... no big deal.
I should say this: the current limiting adjustment is intended as a safety net, not as a CC supply. The limit is a little vague. In those days, CC wasn't such a normal thing. As best I understand it, you want an infinitely high output impedance for CC and zero for CV, so supplies that try to do both must compromise a little somehow in their output circuitry.
I suspect the HP's are similar to the PD's in most ways, including their precision versions (uhm... 6111? 6112? Others?).
Hello. I trust your experience more than my research. I’m going to spend in the neighborhood of $200 on a power supply. I need/want dual output, up to 30v, not sure about amps. I don’t mind servicing older stuff and actually like vintage stuff that is reliable but need it to work from the start as my project has a timeline. Based on past experience would you buy two KORAD KA3005’s (or comparable) or would you purchase a used, dual output HP, Tektronix, BK or similar off of eBay. I’m new with limited knowledge so if you have other suggestions please feel free to share other possibilities. Any help is appreciated.
Hello. I trust your experience more than my research. I’m going to spend in the neighborhood of $200 on a power supply. I need/want dual output, up to 30v, not sure about amps. I don’t mind servicing older stuff and actually like vintage stuff that is reliable but need it to work from the start as my project has a timeline. Based on past experience would you buy two KORAD KA3005’s (or comparable) or would you purchase a used, dual output HP, Tektronix, BK or similar off of eBay. I’m new with limited knowledge so if you have other suggestions please feel free to share other possibilities. Any help is appreciated.
Have you built or repaired power supplies?
What other test equipment do you have?
What is your project and timeline?
Hello. I trust your experience more than my research. I’m going to spend in the neighborhood of $200 on a power supply. I need/want dual output, up to 30v, not sure about amps. I don’t mind servicing older stuff and actually like vintage stuff that is reliable but need it to work from the start as my project has a timeline. Based on past experience would you buy two KORAD KA3005’s (or comparable) or would you purchase a used, dual output HP, Tektronix, BK or similar off of eBay. I’m new with limited knowledge so if you have other suggestions please feel free to share other possibilities. Any help is appreciated.
Have you built or repaired power supplies?
What other test equipment do you have?
What is your project and timeline?I haven't built any but I'm gathering parts. I have a few laptop battery packs. I'm intimidated by the thought of it. Is there a build you would recommend? This is all new to me. I don't have any real gear other than a couple of voltmeters and an old, currently misplaced oscilloscope that my dad used to use many years ago. My project is already late, lol. I sent a message to an eBay seller tonight on an HP 3620. We'll see what comes of it. If that doesn't pan out there are a few other brands/models I'm watching
Hello. I trust your experience more than my research. I’m going to spend in the neighborhood of $200 on a power supply. I need/want dual output, up to 30v, not sure about amps. I don’t mind servicing older stuff and actually like vintage stuff that is reliable but need it to work from the start as my project has a timeline. Based on past experience would you buy two KORAD KA3005’s (or comparable) or would you purchase a used, dual output HP, Tektronix, BK or similar off of eBay. I’m new with limited knowledge so if you have other suggestions please feel free to share other possibilities. Any help is appreciated.
Have you built or repaired power supplies?
What other test equipment do you have?
What is your project and timeline?I haven't built any but I'm gathering parts. I have a few laptop battery packs. I'm intimidated by the thought of it. Is there a build you would recommend? This is all new to me. I don't have any real gear other than a couple of voltmeters and an old, currently misplaced oscilloscope that my dad used to use many years ago. My project is already late, lol. I sent a message to an eBay seller tonight on an HP 3620. We'll see what comes of it. If that doesn't pan out there are a few other brands/models I'm watching
OK
Still not sure what your project is but it sounds like you have something in mind that needs a power supply. Some people like to build a power supply, others are into refurbishing/repairing power supplies - both approaches can be good ways to learn and/or keep the budget down.
Having said that, if everything is new to you then I think you might be better off starting with a few pieces of reliable and reasonably accurate pieces of test equipment. If you have a decent power supply and a decent DMM then when you measure V, I, and R you will have some confidence when your measurements and calculations agree, or some reason to relook the measurements and/or calculations if they don’t agree.
It depends on how much adventure and experimenting you want to do - but if you are new to electronics and you want to learn and build stuff I’d recommend starting with a few decent tools. Along these lines, a used power supply might save some budget but for about $110 you can get a 30V 5A Korad that will be fairly accurate. Starting with a new working PS from a reliable seller is probably going to be a better experience than starting with a used PS but YMMV. A KA3005D from Amazon can be returned if it isn’t working or doesn’t meet your expectations. I’ve had one for about 10 years and it’s been rock solid; I bought a 2nd unit a couple years ago, and I gave another one as a gift to a new EE. Until you know what else you expect from a PS it’s likely all that’s needed.
If you start with one Korad and you really need another PS you can buy a second unit. Sometimes it’s nice to have two of the same pieces of test equipment. You can compare measurements, you will be familiar with the UI on both, and if one is used in another location or is unavailable you have a spare.
Read Reply #5 and#6 in this thread:
https://www.eevblog.com/forum/testgear/are-premium-scope-brands-still-justified/msg5448176/#msg5448176
The thread and Reply #5 and #6 are about professional use but the concept applies at some level to enthusiast use also - if you can’t reasonably rely on measurements it can be extra confusing and time consuming.
fwiw, I think you want a linear PS and one with a DC output on/off button, not just an AC on/off button. And then you will want to see how cleanly the output turns on and off - which will be the sound of the rabbit hole telling you maybe you need to buy an oscilloscope to see and measure the waveforms.
edit: and then you can post your scope’s screen captures of the PS output on/off, at which time you will realize you might need some different probe grounding techniques and accessories to avoid ringing, etc and help you confirm your PS has relatively low ripple, and so on and so forth….
Given your questions and comments I don’t think you will regret jumping into the rabbit hole - but to get the best experience I suggest using a good ladder.
The trick to getting a ladder that will enable an ee (non-degreed electrical enthusiast) to safely and enjoyably climb in and out of the rabbit hole, imo, is to get well grounded (haha) in Ohm’s Law. This means doing enough simple math to understand and reasonably predict the relationships that result from V=IR.
Print the wheel and post it near your bench.
https://www.formulacalculators.com/ohms-law-calculator/
DC is a good place to start, then when you get to AC you can build on the foundational concepts and math learned with DC. AC will add things like RMS. Along the way you will start to recognize the concept of reactance as you distinguish impedance from simple resistance. The oscilloscope can help you visualize some of this and if it has useful math or measurement readouts the scope can help you connect the wave form insights to measurement insights. Things like Peak to Peak vs average vs RMS and 50 ohms vs 1 M ohms will start to show up over and over like markers on your rabbit hole ladder. This is a long way of saying you don’t need an expensive DMM but I’d get one with TRMS vs average RMS. When you see numbers like .707, 1.414, and 2.828 in your dreams you will know you are making progress
And when this chart makes sense you will be another ladder rung proficiently into the rabbit hole.
https://www.minicircuits.com/app/AN40-012.pdf
fwiw, from an early rabbit hole journey:
https://www.eevblog.com/forum/testgear/fluke-17b-rms/
For high voltage stuff, get a Fluke or Brymen. For low voltage stuff get one or two Aneng 8008 (save money and get good features with surprisingly good accuracy).
The KA3005P adds the programmable PC interface and won’t cost much more than the KA3005D (but you might find the software a tad primitive). Both the D and P offer excellent value for the price.
As for scopes, just take the elevator into the rabbit hole, get off on the Siglent floor marked HD.
This advice is intended to save you time and money. Enjoy the journey, it is likely to be fascinating.
edit: Maybe add one Aneng 8008 from Amazon to your Fluke and Klein collection and you are set on DMMs.