KORAD KA3003D-3S - Precision Variable Adjustable 30V, 3A Triple DC Power Supply Digital Regulated Lab Grade

PRO'sProfessional Lab-Like Power Supply FeaturesOutstanding Build QualityVersatile Triple SupplyAttractive and Impressive LookingCON'sModerate fan noise, always runsFixed 5 Volt supply concernsJust received the KORAD KA3003D-S3 Precision Variable Power Supply and will provide a preliminary review. I should point out that this is a first impression/test with the unit so my review is not complete in terms of testing all possible features. Perhaps a future update will include further results from testing.DELIVERY / SHIPPING / PACKAGING - Outstanding:It arrived two days before the indicated delivery date, so kudos to the vendor. The unit was well packed in double-cardboard boxes.ACCESSORIES - Par for the Course:The unit comes with a small printed "user manual", 3-prong grounded power cord, and two sets of banana-plug-clip cords with clips on them.USER MANUALThe user manual does a decent job of covering the many buttons and dials of the two variable power supplies. While the power supply is not at all difficult to use, you MUST read the user manual because there are a number of features to become familiar with. In any case, in spite of the many dials, indicators and intimidating appearance, the unit is really very easy to use once you understand what's going on.Pay close attention to page 11 where there is a diagram that refers to "serial" and "parallel" operation mode: One thing you may want to do is use the two variable supplies for op amp design work where you need a bi-polar supply of equal and opposite polarities. Using two power supplies in series is what the manual is referring to where you use both supplies with a common SIGNAL ground point (NOT chassis ground which is something else).Similarly, you may want to bridge the two variable supplies to obtain higher output current greater than the 3 amps of an individual supply, and again, the manual refers to "parallel" mode.I ran some tests with SERIAL mode turned on and you can see the results further on titled USING SERIAL MODE.The user manual does a decent job of explaining the units dials, etc. but it could have been a bit better with some of the explanations, such as serial and parallel mode.The manual is well printed and easy to read and there's contact information on the back to reach Korad directly if you need to. It would be nice if the manufacturer could provide a user manual in PDF format so it can be downloaded and saved. I visited the Korad website and unless I missed something I could not find a PDF version of the user manual.BANANA-PLUG-CLIP CORDS:This is a triple output power supply, but only two pairs of cords are provided. You'll need to provide the 3rd pair yourself if you intend to utilize all three supplies simultaneously.The wire gauge for the supplied cords seems a bit skimpy especially if you intend to use the supply at or near its 3 amps rating. You might want to find heavier cables of make them yourself with banana plugs and heavier flexible stranded copper wire, especially if you need slightly longer cables from the power supply to your breadboard (However, it's always best to keep your power distribution cables as short as possible). Probably for most applications the supplied cables should be sufficient.GENERAL:For starters, this is definitely not your grandmother's idea of a bench power supply... if she even knew what a bench power supply is.The KORAD KA3003D-3S is a hefty, though compact, triple output lab-quality-like power supply that has two adjustable voltage outputs and one fixed voltage output. The two variable output supplies can each be individually adjusted from 0 V to +30 V, and the third output supply is supposed to be fixed at +5 V. These voltages are with respect to the black negative terminal for each power supply and NOT to the common ground terminal on the front panel (see below under GROUND TERMINAL for info on the ground terminal). In addition, the adjustable 0 ~ 30 v supplies can be current limited individually, over-voltage and over-current protection can also be applied through the front panel controls. If that were not enough, each adjustable power supply can be "fine tuned" in terms of its voltage and/or current output through the use of the controls on the front panel. And on top of all that, each adjustable power supply has 4 different memory settings that can store and recall what ever setting you set the outputs to previously. The third and fixed 5 volt supply cannot be adjusted... more on the fixed supply later under testing.BUILD QUALITY: Outstanding:The unit is impressive looking with its numerous knobs, buttons, and bright digital front panel indicators. However, in spite of the knobs, buttons and indicators, the layout is well organized and functions are easy to see from the illuminated panels for each adjustable supply. Some buttons take on double-duty. The case is all metal construction and has a large and solidly attached carrying cord on the top to make it easy to carry around if desired. The power cord is a heavy-duty three prong plug grounded type that requires an AC power socket with a ground. The quality of the dials and buttons are first-class, no cheap controls used here. The illuminated display is large and bright. The unit is attractively styled, and is rather compact considering it houses three power supplies. Weight is what you'd expect for a unit with three separate power supplies. There are two exhaust fans on the rear of the housing which are physically close to two large internal heatsinks. The manual shows both a USB and RS232 connector on the back panel: The model I purchased did not have the RS232 and USB connectors but there is a model up that has both connectors if you need the ability to program the power supply externally.Overall, the construction is very solid and gives a very favorable and impressive appearance sure to make you look like the High Priest of Power to your associates if that is your objective.FRONT PANEL CONTROLS AND LAYOUT - Very Good:This is a triple output power supply for the bench. The unit is divided into two very similar looking halves which appear to be essentially identical with some slight differences. You will have to pay close attention to the Front Panel Description in the User Manual to get an idea of how these two panels are related and to to interact with the controls.POWER OUTPUT CONNECTORS - Satisfactory, but unclear:Since this is a triple output power supply you'd expect there to be three sets of power terminals, and so there is with each sets terminal colored red for the positive terminal and black for negative terminal. The unit also has a green terminal indicated as ground that is placed right after the first set of positive and negative connectors. I'll talk about the ground terminal more further on.At first impression and without reading the user manual, one can clearly see that there are three sets of power output terminals, but which set is for which one of the three power supplies is not really clear, and what really makes it unclear is that, other than the usual red and black terminals, none of the set's of terminals is marked on the front panel. Marking is probably not really necessary and the location of the terminal pretty much suggests to what half of the unit they are related. However, it would be useful to at least mark the fixed power supply terminals with "Fixed Supply 5 Volts" or something similar just to identify it.INITIAL TURN ON AND TESTING:Upon initial power on, all panel indicators come on.The illuminated indicators show digital values for voltage and current for the variable output supplies only. There is absolutely no voltage or current indicators for the fixed +5 V supply.VARIABLE POWER SUPPLIES:To be noted is that each of the two 0 V to 30 V variable power supply output terminal are not active when the unit is first turned on. So regardless of what voltage was set or subsequently set, the output voltage will not automatically be present at the output terminals unless one presses the off/on button on the front panel for the variable supply one is using; and there is a separate off/on button for each of the two adjustable supplies.The requirement to actually enable the output terminals using the respective off/on buttons may or may not be an issue depending on how you're using the two variable supplies. For example, if you're working with op amps and using a traditional positive and negative power supply with the negative output of one supply connected to the positive output of the other which serves as a common zero voltage point (signal ground), then you'll want to manually enable both supplies simultaneously so that both outputs become active simultaneously (or as close to simultaneously as possible) if that matters in your circuitry (if you're using a single variable supply for your op amp design(s) then there's no real concern). IMPORTANT: If you plan to use both variable power supplies to power op amps or other circuitry where you need equal but opposite polarities maintained at all times with respect to a common signal point (signal ground) you should use the SERIAL mode of this unit which I've covered below under USING "SERIAL" MODE.WHICH SET OF TERMINALS IS FOR WHICH SUPPLY:Although the front panel does not indicate which set of terminal are for which of the three power supplies, it's rather simple once you know. The terminology used in the user manual is "channels". So going from left to right, for each set of terminals, power supply 1 is "channel 1", power supply 2 is "Channel 2" and finally power supply 3 is "Channel 3". Channel 1 and channel 2 are for the two 0 to 30 variable supplies, and channel 3 with its set of terminals at the far right is for the fixed 5 volt supply.GROUND TERMINAL (earth ground):Going from let to right, after the first set of power output terminals for the first variable power supply (channel 1), is a single green colored "ground" terminal. This "ground" is actually an earth ground: my testing indicates that the ground terminal is electrically isolated from the two variable power supply output terminals as well as the fixed 5 volt power supply - this isolation is as it should be. The green ground terminal is tied to the metal case of the power supply housing and it extends out on the power cord's ground prong.For safety reasons, because the housing of the KA3003D-3S is metal it's important that the electrical AC outlet used to power the unit is properly grounded, otherwise neither the unit, nor the ground terminal at the front panel will truly be grounded.IMPORTANT WARNING: Normally a ground terminal such as this, which is tied to the metal housing of the unit, would NOT be used in your circuitry as a ground point or signal ground. A signal ground and a chassis ground are two different things. So, if you're working with any circuitry or equipment that isolates power connections, such as an isolation transformer or opto-isolators, DO NOT EVER tie the isolated grounds into your circuitry because doing so will nullify the isolation and will pose a serious shock hazard. While many power supplies position a ground terminal on the front panel I feel it is much better to place it at the rear panel.NOTE: Not all earth grounds are of equal quality. Some grounds are better than others and ground quality can vary by temperature and weather conditions depending on where you live and the actual specifics of how your "ground" is configured. If you have any questions or concerns about the grounding or the quality of the ground at your electrical outlet consult with a licensed electrician. However, be aware that with any device using a metal case, such as the Korad power supply, you should always use a properly grounded AC outlet using the 3-prong grounded power cord which is supplied with this unit. Do not use an adapter that breaks to ground so that you can plug the unit into AC outlet that has no ground prong. However, in the absence of a properly grounded electrical outlet the power supply will of course still function but the case will not be grounded - so be aware of that.USING "SERIAL" MODE: If you intend to use the power supply to provide a bi-polar voltage source, for example equal positive and negative values perhaps for working with op amps that generally require a bipolar supply, you can activate the unit's "SERIAL MODE". You can consider "serial" mode to be a dual tracking voltage supply.In SERIAL mode both variable power supplies are tied in series INTERNALLY and the output voltage of both variable supplies is controlled by the voltage adjustment knob on the right side power unit. If you use a common signal ground (see below under item c) in SERIES mode, adjusting the voltage knob of the right side supply both power supplies voltage to change the same amount - in effect, tracking. If you use the common point (not the Chassis Ground terminal) which is the negative terminal of the left supply with the positive terminal of the right supply - adjusting the voltage with the right side voltage know will cause both supplies to change their voltage simultaneously with respect to the common signal ground.Also, In series mode it's possible to create a supply of up to 60 volts by using the positive terminal of the left supply and the negative terminal of the right side supply only.Activating serial mode is accomplished by pressing and holding down the OVP (over voltage protection) button on the right-side set of dials until the SER lighted indicator appears in the display section.Once the SERIAL mode is activated here's what happens:a) SER is shown on the front panel display.b) The negative terminal of the left variable supply is internally connected to the positive terminal of the right side variable supply - so YOU DO NOT NEED TO PLACE A JUMPER BETWEEN THESE TERMINALS TO CREATE A BI-POLAR SUPPLY.c) The large voltage adjustment dial on the right half power supply panel will control the bi-polar voltage between the positive terminal of the left power supply and the negative terminal of the right side variable power supply - the dial on the left side panel used to adjust voltage of the left side power supply will become inoperative and will have no effect of the overall voltage adjustment if used.d) For your positive voltage you will use the positive terminal of the left power supply, for your negative voltage you'll use the negative terminal of the 2nd power supply. If you need a signal common or "signal ground" you'll connect a third banana plug to either the left side power supply negative terminal or the right side power supply positive terminal (remember that these terminals in SERIAL mode are now bridged together internally) and extend this third lead to your breadboard as the common signal ground. Adjustment of the right side supply voltage dial will change the voltage as measured on these terminals. This arrangement is displayed on page 11 of the user manual shown on the left illustration as "Load connection figure for series mode". Note however that the illustration does not mention that the third lead can be used to form the signal ground (not the same as the chassis ground).UNEQUAL BI-POLAR VOLTAGE MODE: However, If you need a bi-polar supply where there are unequal positive and negative voltages referenced to a common signal ground (not chassis ground) then you cannot use SERIAL mode as described above since in serial mode both variable supply voltages with respect to the common signal ground change equally hen making voltage adjustments. So, for a bi-polar supply with unequal positive and negative voltages you'll need to use each variable supply individually as is (without activating SERIAL mode) and place an external jumper between the negative terminal of the first variable supply and the positive terminal of the 2nd variable supply and then run a jumper from either of those terminals to your breadboard to serve as the common signal ground point. In this mode, the left side positive terminal is still your positive voltage (with respect to the common signal ground) and the 2nd power supply negative terminal is your negative voltage (with respect to the common signal ground) and you can adjust the positive and negative voltages separately to have different voltages with respect to the common signal ground.PARALLEL MODE: I did not test the units "parallel" mode. Presumably it should bridge both variable power supplies positive and negative terminals together internally, similarly to the series mode, to provide a higher current output capability but with a 0 to 30 volt max.THE FIXED 5 V SUPPLY:For all the things this power supply can do, the fixed 5 volt supply is to me is a surprise and somewhat disappointing: The two variable supplies of the KA3003D-3S have been lavishly appointed with indicators and controls and can work in both series or parallel modes, but the fixed 5 volt supply has been miserly provided. Other than providing output terminals for the fixed supply, there is absolutely no voltage or current indication capability for the fixed +5 volt supply. In short, the fixed supply runs "blind" in that you don't know what its real voltage is or the current its providing under load unlike the two variable supplies which show constantly both voltage and current. Now this may or may not matter to you. If you really need to monitor the voltage for the fixed supply you'll need to connect some kind of external voltage meter arrangement to it, or use a spare voltmeter if you have one. Of course monitoring current is a bit more involved and is probably more trouble than it's worth, and considering your setup could interfere with the tolerance and regulation of the fixed supply I wouldn't bother trying to monitor current, but monitoring voltage is certainly doable though it requires an external setup.Also to be noted, unlike the two variable supplies' output voltages that can be enabled or disabled using the off/on buttons on the front panel to control whether the voltages appear at the output terminals, there is no such off/on button for the fixed 5 volt supply: the fixed 5 volt supply becomes active with its voltage appearing on its output terminals immediately when the AC power to the unit is turned on. This may or may not present issues for you when connected to a project where multiple voltages from two or more supplies are being used so it's something to be aware of.FIXED SUPPLY VOLTAGE TOLERANCE:On page 18 of the user manual it indicates that the tolerance of the fixed supply voltage is 50 mV (0.050 volts). Since the tolerance can be higher or lower it means the fixed 5 V supply can be higher or lower by 50 mV. So for a stated 5 V supply with a 50 mV tolerance the voltage can be anything between + 4.95 volts and 5.05 volts and still be "within tolerance". While 50 mV is small it is none-the-less a measurable amount.For example, on the unit I received and allowing the unit to remain on for the recommended 1/2 hour, the fixed 5 volt supply measured 4.978 volts. Measurement was taken with a digital voltmeter having an input resistance of at least 10 Meg ohms per volt.Also, keep in mind that if you intend to use the fixed 5 volt supply with TTL logic, such logic generally has a tolerance of +/- 0.25 volts for the required 5 volt supply. With +/- 0.25 volt tolerance the TTL supply voltage can go as low as 4.75 volts or as high as 5.25 volts and the TTL logic should still function within nominal specifications - presuming the voltage does not drop any further and/or current does not exceed what the supply is able to deliver.In the case of unit I received, the voltage measured for the fixed 5 volt supply was 4.978 volts with no load, and that's a difference of 228 mV (0.228 v) above the minimum TTL lowest working voltage of 4.75 v. Still certainly within working limits for TTL logic. However, if regulation under load drops further the 5 volt supply might present issues for TTL logic circuitry. This is something only you will find out if you use the fixed 5 volt supply for TTL work over time.The user manual makes no mention of current limiting of the fixed output supply, so presumably - again, a dangerous word - there is no current limiting of the fixed 5 volt output and it will provide current up to its rating of 3 amps if your circuitry draws that much current - something to be aware of.FAN / FAN NOISE:As I previously stated, the unit has an exhaust fan at the rear of the cabinet. My unit ran in a room with the temperature at 70 degrees Fahrenheit and the fan was running. In normal operation the fan seems to run continuously regardless of the ambient temperature. There's no mention in the user manual whether the speed of the fan will increase with an increase in ambient or internal temperature.The fan noise level is relatively low but still noticeable. If you do any work with audio circuitry you'll be especially aware of ambient noise and you will hear the fan even though it's not very loud. Depending on precisely the nature of audio work you do you may or may not find the fan noise objectionable.FINAL PRELIMINARY ASSESSMENTAside from the issues with the miserly appointed fixed 5 volt supply, the unit is well constructed, has excellent controls for both variable power supplies, has voltage and current protection and limiting, has serial and parallel modes, with the addition of memory settings to recall voltages literally at the touch of a button - if you have need for that.However, It seems that it would have not been too difficult a task to include a button, or use an existing button that serves double-duty, to provide at least voltage indication using one of the existing display elements on the right half of the unit where the fixed 5 volt supply provides its output.I have to presume the omission to provide any indication for the fixed 5 volt supply was an intentional way to reduce final cost. And while power supplies can cost much more than the cost of this unit, into the many hundred or thousands of dollars, the price is above average for a bench supply so the omission of any kind of indicator for the fixed supply is unfortunate. But considering the fixed 5 volts supply is likely to be used primarily with TTL logic circuits (TTL requires a fixed 5 volt supply) it can be "presumed" - a dangerous word - that a voltage indicator will not be missed. Some would agree that last statement while some would not. I am in the latter group.Additionally, an probably more important, aside from the lack of a fixed voltage indicator, it would have been more comforting to be able to fine-tune the fixed 5 volt supply up or down perhaps 1/4 to 1/2 a volt to fine-tuned it or to compensate for changes over time as the unit ages.I was curious to know if the fixed 5 volt supply could be adjusted internally and so I contacted Korad. I am please to have gotten a prompt reply back with the answer to my question. I'm not pleased though that the reply stated the fixed 5 volt supply could not be adjusted.The front panel ground terminal: The incorporation of a ground terminal is to be expected on most pieces of electronics gear that use a metal housing. However, it seems that the ground terminal would serve better if it were placed on the rear panel rather than right out on the front panel. For newcomers to electronics, the ground terminal may present some confusion, especially since none of the three voltage supplies are referenced to it, which they should not be.The user manual should mention some precautions with the use of the ground terminal such as NOT connecting isolated grounds to it or extending the chassis ground into the breadboard circuit which is not ordinarily required. However, I suppose Korad might assume anyone purchasing a power supply as this would know about such things so they've left such explanations out of the user manual.Although this is a very capable power supply I would not call this unit a "lab quality" unit even though it has many commendable features similar to a true lab quality power supply. The inclusion of the fixed 5 volt supply lacks the ability to read the voltage and the tolerance could be better and there's no current limiting on it as well. And more specifically, there no way to fine-tune the fixed supply - for example, what happens when the fixed supply voltage goes out of tolerance over time?Regardless of whether or not these observations with the fixed 5 volt supply may or may not be important to you, this is a very capable power supply that should provide dependable service if your work doesn't need more than 3 amps per supply (or 6 amps in "parallel" mode).If you like this unit but need more than 3 amps KORAD does offer the KORAD KA3005D-3S, also a triple power supply (looks exactly the same as the KORAD KA3003D-3S for slightly more bucks) that can put out 5 amps for each of its three supplies. I didn't know of the higher powered unit when I made my purchase. However, for the slightly higher cost I would have preferred to 5 amp model.You can, of course, find three separate power supplies that together would probably cost less than this one, especially if you don't need the memory recall capability. But if you want something that is well built, is attractive and impressive, does the job, has voltage and current limiting, and with memory recall capabilities - and you can overlook the issues I've pointed out with the fixed 5 volt supply - this is the power supply you'll want. And if you need higher current capability look at the KORAD KA3005D-3S which puts out 5 amps per supply.In conclusion this is a very attractive and fun to use power supply with lots of features. I wanted to give this product a full 5 stars because of its features and build quality, but because of the issues with the fixed 5 volt supply and the low, but still very noticeable fan noise, I gave it 4 stars.With a caveat regarding the issues I've mentioned, yes, I would definitely recommend this product to a friend.

I have been tinkering with breadboarding electronics with my two boys, and bought this to avoid all the battery packs and regulators. I really like it so far. The two adjustable power supplies have a lot of nice features, nicer than much pricier supplies I used to use long ago - digital setting of supply voltage and current limit, or of supply current and voltage limit, output on/off buttons for each supply, maybe more. My only complaints are that the manual is not very good (how to get into current control mode, for example), and the front panel does not clearly identify which outputs go with which controls (or the 5V supply). You can figure it out, though. Having voltage and current meter readings automatically available is very useful and educational to my kids ("Hey wait, it's using 70 mA, that LED can't take that much, turn it off quick!"). I can't comment on the reliability, but I'm very pleased with it so far.

Received this unit for my birthday from my girl friend :) Unit was packed well with incld'd manual, two dc cord sets and power cable. I agree with others the fans are a bit loud but not so bad as to drive me off. Tested the units E and I and the entire range is as specified. OCP works well, havent tested OVP yet. Opened unit and it is built very well. All internal plug connectors have a dab of silicon rubber to hold them in place.If you are thinking of modding this unit for serial/usb, it might be doable as the circuit board has blank spaces for the components. I have no idea if the smarts is the same as the 'P' suffix models. looks like a square smd usb convertor and a smd rs-232 convertor chip plus caps and resistors are needed. Serial might be easiest and least expensive in parts and labor to try. I havent looked into getting the software yet. So far I like it.

It took a couple of weeks to arrive. It is quite heavy, but well packaged to avoid damage. The "classic" HP 6236B Triple Output power supply I had been using finally gave up the ghost and went to that big junk pile in the sky, so I replaced it with the Korad KA3003D-3S. The Korad is a much more sophisticated power supply:* Digital read outs* Dedicated 5V output* Memory, allowing the user to retain up to 4 different pre-set values* Over current protection (very sensitive - which is great)My only "whine" is that the Korad is heavy (+15 lbs), but I would expect a quality power supply to be hefty.I would definitely recommend to others.

Very good so far. It works as advertised

Good product