Info on Skytronic 650.682 0-10A 0-30V Adjustable DC Power Supply - Page 1
Forum section: electronics / testgear

author: dominicM
author_rank: Regular Contributor
timestamp: September 08, 2016, 04:48:17 pm
content: :-DMMHas anyone had this power supply or has any info on it? I can't find a decent spec sheet or manufacturer product page. Any opinions on how good/bad it is? Did the manufacturer go bust or change names or something? I went ahead and bough it used on ebay so I am hoping it's usableThe basic spec seems reasonable for my very basic needs.Farnell listing has some info and images seem to match:http://ie.farnell.com/unbranded/650-682/power-supply-1ch-30v-10a-adjustable/dp/4283200?CMP=KNC-GIE-GEN-SKU-UNB&gclid=CjwKEAjwmMS-BRCm5dn51JLbp1wSJACc61tF9de6JS7PE497nPIoe8M7aH1FxH2CqKYkgHvDcRMcnhoCHEzw_wcB&mckv=s9hdjsd6G_dc|pcrid|74506267146|kword|650.682|match|p|plid|

author: bitseeker
author_rank: Super Contributor
timestamp: September 09, 2016, 12:54:56 am
content: On the outside, it looks like the myriad similar power supplies that are sold under various names. Some are OK, others are quite bad. I haven't seen inside this particular incantation. Unless someone who owns one can give definitive info on its quality, I'd err on the side of it being not so good.

author: dominicM
author_rank: Regular Contributor
timestamp: September 09, 2016, 08:35:10 am
content: I didn't expect it to be good as such, just as long as it's good value for money I am happyI am surprised though how expensive it is on the farnell website. It also lists it as 12kg which seems very heavy considering similar spec ebay cheapies are only about 2kg, maybe it's just a bad listing though...

author: bitseeker
author_rank: Super Contributor
timestamp: September 09, 2016, 05:37:23 pm
content: I'm sure it'll operate as a power supply. If you get it, you may want to search for some of the similar models that have been discussed here to see what issues were found to make any corrections to yours. The most important ones, of course, being proper grounding, no solder blobs that might create short circuits, wires rubbing on sharp edges, loose wires, bad solder joints and so on.The weight difference, if it's not a typo, is likely due to one being linear (heavier) and the other switched mode (lighter). Linear power supplies have large heat sinks and transformers, but provide cleaner output.

author: dominicM
author_rank: Regular Contributor
timestamp: September 10, 2016, 10:04:32 am
content: The weight looks accurate as it's listed in several places. Seems very heavy considering it's relatively small size. I take that as a good sign as other power supplies seem to be lighter per max current output. Will definetely open it up to check for any issues. Not sure what a similar PSU would be in this case as this has no single brand name and model turns up nothing but this thread.I noticed some cheap PSU's have a metal bridge between negative and ground binding posts, why is that? Is it simply that it doesn't have that bridge internally?

author: bitseeker
author_rank: Super Contributor
timestamp: September 10, 2016, 05:48:01 pm
content: The so-called "Technical Data Sheet" on Farnell doesn't say much. The ripple specification sounds like a switched mode power supply (mV in the tens to hundreds for SMPS vs. single-digit mV or less for linear), however the weight and the large heatsink in the photo are indicative of a linear power supply.The 30V 10A Chinese power supplies are available in either switched mode or linear, so be sure you're getting the one you want. The lighter weight you mentioned fits the SMPS ones and the heavier fits the linear models.To find some other similar power supplies, search for HY3010. You'll find many variations, designated by a letter, such as HY3010D (usually a linear version), HY3010EX (usually an SMPS), HY3010EP (usually SMPS and programmable), etc. These are not all the possible names, nor are they standardized nomenclature between brands, though there is lots of copying.Since they all look similar, which ones are good or bad can be a bit of a shot in the dark. I've heard the Mastech ones are OK as compared to some others, but even that's no guarantee that the one you get will be. I don't know for sure if Volteq is the same inside as Mastech, but there is a US distributor that has the same looking web site for both.http://www.volteq.com/http://mastechpowersupply.com/Your country isn't listed in your profile (no flag icon). If you're in a location that has availability of used test equipment at a good price, I'd recommend getting a used HP/Agilent, Xantrex/Sorensen, Lambda/TDK, Power Designs, or other well-regarded brand of power supply. Unless you really need a brand new one, buying a high-quality used one, depending on your location, often provides the best bang for the buck.

author: dominicM
author_rank: Regular Contributor
timestamp: September 10, 2016, 06:59:40 pm
content: I guess will know soon enough, should arrive next week hopefully. Either type is actually fine since I don't need anything specific, just a general PSU for convenience more than anything else. The listed price on farnell for the one I bought and for the ones in your links seem very high, is that an actual market / reasonable price? Second hand high end equipment isn't really an option, maybe in the future if I need something more decent I'll look into it.

author: TheBay
author_rank: Unknown
timestamp: September 10, 2016, 07:38:42 pm
content: It's a linear PSU probably with a toroidal transformer.Did you see actual images of the one you bought, some have banana sockets with no binding posts and some have binding posts.In the UK that is sold as Skytronic or Mercury.As already noted in this thread there are loads of these PSU's sold under different names, mainly with a HY Prefix.Not the best image I could find, but this is the inside of one of these:

author: TheBay
author_rank: Unknown
timestamp: September 10, 2016, 07:41:01 pm
content: Some more pics here, click the images:http://elektrotanya.com/?q=en/content/digitalis-labortap-toroid-trafo-ujra-tekercselese-megoldodott-de-adodott-mas#127929

author: bitseeker
author_rank: Super Contributor
timestamp: September 10, 2016, 08:14:26 pm
content: Quote from: dominicM on September 10, 2016, 06:59:40 pmOK, I'm looking forward to seeing inside the one you get.QuoteIt's hard to say if the price is reasonable without knowing how it's designed or built. If it's well done, the price may be fine. If it's not well done, then it may be too high. I've seen quite a wide variation of prices.QuoteNo problem. Second-hand equipment is not a viable option for everyone, but it's good to check just in case it will work.@TheBay: Thanks for the pics.

author: dominicM
author_rank: Regular Contributor
timestamp: September 14, 2016, 03:17:20 pm
content: Quote from: TheBay on September 10, 2016, 07:38:42 pmYes that's the same one. It has banana plugs so I will probably want to replace them with binding posts.@bitseekerI only paid 70 euros delivered which is slightly less than new eBay cheapies which are either half the current rating or switching. This one also has output on/off button which is nice. Will post some pictures when it arrives.

author: TheBay
author_rank: Unknown
timestamp: September 14, 2016, 06:16:10 pm
content: Quote from: dominicM on September 14, 2016, 03:17:20 pmI find banana posts only a pain in the bum, swap them out when you get the PSU if you prefer binding posts. Fingers crossed it's all working well when you get itHave a look at post #8 I put a link to some links of some more internal pictures of these.

author: dominicM
author_rank: Regular Contributor
timestamp: September 14, 2016, 06:47:27 pm
content: Yeah, I saw the pictures and it looks the same as the one I ordered. Also, is there any significant advantage / disadvantage of toroidal transformer in a power supply? Seems uncommon, just wondering if there are any consideration with toroidal vs EI.

author: TheBay
author_rank: Unknown
timestamp: September 14, 2016, 07:23:21 pm
content: Quote from: dominicM on September 14, 2016, 06:47:27 pmPro's and con's to both, depends on the application and current. Will be fine for that though.

author: dominicM
author_rank: Regular Contributor
timestamp: September 16, 2016, 02:53:45 pm
content: Finally got the PSU and here are the images. A few more cobwebs than I expected but otherwise seems fineOne thing that caught my eye was the POT(pictured) that looks different than other 4. It's the fine voltage adjustment. Maybe it's been replaced?Couldn't upload images here due to restrictive limitations so here's a link:http://owncloud.dominicm.com/index.php/s/aPk8tT6RZcR3u9NI never had a bench power supply before so I haven't done much testing it yet, don't want to blow anything upA few initial observations:The small fan is relatively loud and does go on even with no load (second fan is off).Both displays shows 00.0 unless output button is on.Voltage is displayed as 00.0 when CC is set to minimum or close to it (C.C. led on).C.C. led sometimes but not always flash when adjusting voltage (relays click).Current displays 00.0 with no load.C.C. led comes on monetarily at power off (no oscilloscope to test for spikes).GND banana plug wire is crimped and screwed to the bottom of the case with a shake proof washer. The other ground connected is the same on other side of bottom case.Any of these seem abnormal? I read that to set the current limit shorting the PSU is the way to go, is that correct? Anythings to watch out for in general? Any good videos or other resources relating to basic bench supply usage?

author: TheBay
author_rank: Unknown
timestamp: September 16, 2016, 03:08:39 pm
content: Quote from: dominicM on September 16, 2016, 02:53:45 pmAnswered what I could above, ideally need to look at a manual or a video of one in operation to give answer properly.Interesting that was in use in the UK

author: dominicM
author_rank: Regular Contributor
timestamp: September 16, 2016, 03:12:53 pm
content: Why is that interesting? It was ordered from UK btw.

author: TheBay
author_rank: Unknown
timestamp: September 16, 2016, 03:19:44 pm
content: Quote from: dominicM on September 16, 2016, 03:12:53 pmAh I didn't realise, I thought you might have bought it from your home countries eBay.

author: dominicM
author_rank: Regular Contributor
timestamp: September 16, 2016, 03:32:14 pm
content: Well I did, but ebay lists items from other countries too. Not too much choice from only local sellers anyways

author: bitseeker
author_rank: Super Contributor
timestamp: September 16, 2016, 07:10:19 pm
content: Quote from: dominicM on September 16, 2016, 02:53:45 pmI thought you were joking, but there really are cobwebs in there. It'll be good to clean out all that cruft.QuotePossible, or just a different value.QuoteDon't overload it and you should be fine. Overall, it looks OK inside. Better than some examples I've seen myself or elsewhere on the forum.QuoteThe small fan is probably for general airflow and doesn't have any temperature sensing. So, it's always on. You could add your own fan controller.QuoteNormal. It's off.QuoteIf the current is set to minimum, then CC mode will be triggered almost all the time, and voltage will have to drop to keep the current near zero. Turn the current knobs clockwise all the way unless you're connecting a circuit where you need a specific limit. For example, if your prototype should never draw more than 1A, you could set the current limit to something a bit higher.QuoteIf the current level is set to minimum, almost any voltage above zero is likely to trigger CC mode. Turn up the current limit (see previous question).QuoteGood. No load, no current.QuoteYeah, might be a voltage spike. See if your multimeter detects anything. It's not as good as using a scope, but you might see something.QuoteThat sounds good. I didn't see them in the photos, but it sounds fine. Use the continuity setting on your DMM and with one probe on the ground pin of the IEC connector (where the power cord attaches), touch the other probe on the metal parts of the case, handle, and the ground banana jack. Make sure they all beep and the resistance in near zero.QuoteIt depends on the power supply. Some will show you the set value when you turn the knob, then return to the measured display after a short delay. Other supplies require that you short the output leads to set the current. It may also be different with the output enabled vs. disabled. Try it both ways and rotate the knobs. See what it does.QuoteBe sure to check any limits that you set before connecting your circuits. Having them set incorrectly can lead to confusion (why is my voltage so low?) to fried components (voltage set too high).Also, until you have a scope to check for turn on/off spikes, connect your circuit only after the supply is running. There could still be overshoot when the load is attached, but it should hopefully be less than a turn on/off spike.QuoteThere should be plenty on YouTube. Watch several so that any bad advise will appear as unique outliers. Of course, you can always ask for clarification on the forum.

author: dominicM
author_rank: Regular Contributor
timestamp: September 17, 2016, 11:27:54 am
content: Thank you for all the answers, it's a lot clearer now. When shorted voltage shows 0, is that the protection kicking in? Max voltage is 31.4V. The controls are a bit finicky so there's a discrepancy of about 0.05V between measurement and display, with a DMM I can adjust it accurately. It does seem to be over by about 0.03V but that's fine for now. GND is connected to the case and mains input and resistance is about 0. When is GND plug used in practice? Also some cheap PSU's have a bridge between GND and negative binding post, why is that?I am thinking to get this type of binding posts:http://www.ebay.ie/itm/2Pcs-M5-Type-High-Current-4mm-Female-Banana-Jack-Socket-Test-Binding-Post-CK-/191971732480?hash=item2cb2682c00:g:CnEAAOSwYIxX2e0EThe single color red/black ones look cheap to me. The only issue is that they do not have the slot for the wire, does is matter in practise?

author: bitseeker
author_rank: Super Contributor
timestamp: September 17, 2016, 05:57:43 pm
content: Quote from: dominicM on September 17, 2016, 11:27:54 amV = I * R. A short is essentially 0R unless your wire is really long or really thin. 0 * anything = 0.QuoteSee if the documentation states the accuracy of the display subsystem. It may still be within spec. If not, you could adjust it if it bothers you. In general, though, if the accuracy is important, use a DMM and measure it at the circuit or device you're powering, not at the power supply.QuoteThe ground pin on the power plug comes into use if something goes wrong in the power supply in order to keep the power away from you. For example, if a wire inside comes loose or the insulation wears through and touches the metal case, the current will flow to ground and blow the fuse or trip a circuit breaker. Without it, if you touched the case, you would become part of the circuit.QuoteAny PSU can be configured this way. The metal "bridge" is called a shorting bar. A wire could be used as well. Without it, the power supply's output is floating. The positive output is how ever many volts higher than the negative output by the amount you set. However, since it's floating, the negative output's voltage could be just about anything. It could be the same as ground or many volts higher or lower.Most of the time, having a floating power supply is preferred since it doesn't impose any particular point in your circuit to be earth ground (e.g., some circuits have different "ground" points that aren't meant to be at the same potential as earth/chassis ground). However, if you need to have the negative output of the power supply be the same potential as ground, then you install the shorting bar/wire between the negative and ground posts/jacks. Of course, if you use the shorting bar, make sure that wherever you attach the negative output also is (or is intended to be) at earth ground or you may create a short circuit.QuoteNot sure. I've seen these online before, but never in person. My main concern with any binding posts you get for this supply is that it can take the current. The listing says 60VDC and 24A, which is fine if it's correct.QuoteDepends if you ever need to connect bare wires to the power supply instead of banana leads.

author: bitseeker
author_rank: Super Contributor
timestamp: September 17, 2016, 06:07:23 pm
content: By the way, if you get those binding posts, I'd be interested in your feedback/photos of them.

author: dominicM
author_rank: Regular Contributor
timestamp: September 19, 2016, 08:38:05 pm
content: The display is indeed the limiting factor here, good enough for most thing though.These binding posts would be ideal but not widely available:https://www.radioshack.com/products/radioshack-safety-binding-postsWill stick with the nice banana cables included and some clips until I decide on the posts.Used the supply a bit, it does seem to have fairly bad voltage spike when enabling output. At 17V setting on the PSU momentarily registers 26V on the DMM.

author: bitseeker
author_rank: Super Contributor
timestamp: September 20, 2016, 12:30:47 am
content: That's quite a jump. Do you see the same if you enable the output first, then attach the DMM probes? Just want to check that it's not the DMM overshooting its reading. In any case, it'll be good to check with a scope when you have the opportunity.

author: dominicM
author_rank: Regular Contributor
timestamp: September 20, 2016, 09:20:54 am
content: I tried again with 12V set (12.10V measured) and it jumps reliably every time to 21V when enabling output or making contact with DMM.

author: bitseeker
author_rank: Super Contributor
timestamp: September 20, 2016, 07:17:36 pm
content: OK, one more check. If you measure a 9V battery with the DMM, do you see a similar jump in voltage? If so, it's probably the DMM overshooting.

author: dominicM
author_rank: Regular Contributor
timestamp: September 20, 2016, 08:02:48 pm
content: I did not see that coming, it's a decent DMM so would not have though it to be the cause at all. DMM is Extech EX505 btw which looking at other threads turns out to be a bit crappy. 9V battery measures as 8.49V but overshoots to 14.94V.

author: TheBay
author_rank: Unknown
timestamp: September 20, 2016, 09:34:23 pm
content: Quote from: dominicM on September 20, 2016, 08:02:48 pmYeah bitseeker is right, your DMM is overshooting.

author: bitseeker
author_rank: Super Contributor
timestamp: September 20, 2016, 11:52:01 pm
content: A DMM's primary job isn't to measure transients, so such an overshoot isn't a problem per se. Normally, you'd apply the probes and allow a moment for the meter to settle. I wouldn't worry about it. Now that you know how it behaves, you know how not to use it, which is just as important as knowing how to use it.An oscilloscope is still preferred if you want to see how the output changes over time.

author: dominicM
author_rank: Regular Contributor
timestamp: September 21, 2016, 12:53:59 pm
content: Well put. It does seem like Extech DMMs suffer from overshoot in particular. I tried with a really crappy meter and it had no overshoot at all no matter how often I switched the output on/off. It's pretty slow to ramp up though so I don't think it eliminates the presence of a spike.