LF a bench power supply  - Page 1
Forum section: electronics / testgear

author: gore
author_rank: Regular Contributor
timestamp: September 13, 2015, 12:12:12 pm
content: Howdy,As the topic says, I'm looking for some power on my bench. I need some help picking something out. To narrow it down a little bit I want at least two channels. 30 volts, 3A per channel would be okay. The load on/off button is helpful too. I'd be willing to spend 100 - 300€. Can't afford the programmable ones. They cost much more than that. I don't really need those functions anyway. At least not at this point. Most of the brands on these lists are not familiar to me, expect GW instek or Tektronix.My suppliers are:TME catalogfarnell catalog

author: nctnico
author_rank: Super Contributor
timestamp: September 13, 2015, 02:21:40 pm
content: Put Ebay on your supplier list and your budget goal can be met. GW Instek rebrands Chinese low cost equipment so why not buy directly from China?

author: icpart
author_rank: Regular Contributor
timestamp: September 13, 2015, 03:21:25 pm
content: Quote from: gore on September 13, 2015, 12:12:12 pmHi core. I want to warn you about TME. They are bastards because I bought from them the programmable power supply Twintex TPM-3005 a couple weeks ago and it burn on my desk in first day of usage. According to them, there was blown input power transformer because I've switched to 110V which is untruth. It works some hours and just died. They do not acknowledged my warranty. I was forced to pay for the repair of the transformer in my country.If you look for good price for programmable power supply like KORAD 3005 i find it on reichelt.dehttp://www.reichelt.de/KA3005D/3/index.html?&ACTION=3&LA=446&ARTICLE=135688&artnr=KA3005D&SEARCH=korad-this version support PC USB connectionhttp://www.reichelt.de/KA3005D/3/index.html?&ACTION=3&LA=446&ARTICLE=135688&artnr=KA3005D&SEARCH=korad- cheapest variant is that without PC supportAlso I think they ship to all Europe.I dont read your first post about that you look for dual channel supply. On farnell website I've seen a KORAD rebranded dual channel power supply under TENMA brandhttp://uk.farnell.com/tenma/72-10500/power-supply-2ch-30v-3a-adjustable/dp/2251948In reality they are two power supplies side by side in one case.

author: icpart
author_rank: Regular Contributor
timestamp: September 13, 2015, 03:36:33 pm
content: Quote from: nctnico on September 13, 2015, 02:21:40 pmAlso buying any heavy item like linear power supply directly from China doesn't worth the shipping cost (which are huge comparable to item price)+VAT taxes+duty fees.A better alternative is to buy from EU seller. Also in EU you have some warranty and shipping cost are cheaper to send failed item to seller compared if you need to ship your broken power supply back to China.

author: gore
author_rank: Regular Contributor
timestamp: September 14, 2015, 07:35:24 pm
content: Quote from: icpart on September 13, 2015, 03:21:25 pmActually a single channel supply is okay. I have also reconsidered my previous option. What bothers me about these particular supplies is their poor representation of values on the screen. The programmable supplies have good resolution (in the mili volts/amps range). Much more useful. I've looked at the model you ordered from TME. Seems reasonable in the price range. Obviously, it's very cheap, so you can't expect a quality product. Your incident was unfortunate, but now that it's fixed, how is it? Is it worth the price? Should I invest more? Let's exclude the expenses you had due to a faulty unit and TME's warranty refusal.In regards to Ebay and items on China's market, I've looked at it, sure. But as icpart mentioned, it's not worthwhile because of shipping costs and customs fees. Shipping time as well. In case of a faulty unit, you'd be in a lot of trouble. Sending such a bulky item back and forth is a disaster.

author: icpart
author_rank: Regular Contributor
timestamp: September 20, 2015, 05:02:29 am
content: You can't find on market another programmable power supply with that functions and output resolution for that price. The supply itself is good but LCD view angles are awful. You can see the LCD best only on front of it. On desk it is better to raise slightly the front of power supply for better viewing of LCD readings. According to the manual the PSU have 24 bit ADC for readings and 16bit DACs for setting the output voltage and current. The PC software is total crap and seems that don't work fully with my TPM-3005 model. Via PC software I can set up the output parameters like output voltage and current but I can't read any feedback output current or voltage when the power supply is working. I think there is problem with PC software communication and not hardware problem associated with my repaired PSU.If you're going to buy the same model I will ask if you can test whether the software works properly on your future PSU, because I think the PC software is made for TPM-3003 model because I can't setup more than 3A output current via PC.On TME there is also 2 twintex models rebranded from TME under their brand Axiomet AX-3003P and AXIOMET AX-6003P which have respectively voltage range of 0-30V and 0-60V and output current range 0-3A with 0.1mA output setup resolution.Also you can read more info about TPM-3003 model in that threat here on forumhttps://www.eevblog.com/forum/testgear/lab-power-supply-twintex-tpm-3003-worth-the-review/About orders from TME I want to warn you that you can't place any order from them if you don't have registered VAT number.

author: gore
author_rank: Regular Contributor
timestamp: September 24, 2015, 07:08:43 pm
content: I went with the Korad unit you suggested. Just got it from Germany. A relatively cheap bench power supply, but with a couple of mods it's a decent piece of equipment. I've swapped the stock fan and added a thermal control. It makes close to no noise for loads up to 3A. If you don't load it up, it won't make a sound. Unlike the stock configuration, which has fixed values @ X amps. Voltage and current values on the screen are fairly accurate. Swapped a couple of caps too. The Rubicon ones are most likely fake. Last thing I will do is swap the AC input socket. It's the 'push in-held by plastic' kind. Wiggles around a little bit. I like the ones with a couple of screws. Gonna be a perfect fit. All in all - no complaints.A few pictures:Bench1Bench2Bench3Bench4Bench5Bench6

author: icpart
author_rank: Regular Contributor
timestamp: September 25, 2015, 03:50:48 pm
content: Congratulations for your new power supplyYou're done good mods on this PSU.Unfortunately my power supply is dead again with the same problem as before with burned primary winding of the power transformer. Most probably my power supply is total defective and blown again after last repair with replaced new made power transformer in my country. So be aware about of quality of these Twintex PSUs. Also I checked my power supply inside and I saw that the cable connectors are with very low quality and they are very loosen. All are glued with silicon.P.S.On first image I see on your desk some ATX power supplies with some potentiometer and jacks of front of it. I'm curious if you are modify them in some variable ATX version. Because these days I was thinking about to do a similar mod for making more powerful variable power supply based on PC PSU. Also I found very good information on various Russian electronics websites.

author: gore
author_rank: Regular Contributor
timestamp: September 25, 2015, 05:07:12 pm
content: Quote from: icpart on September 25, 2015, 03:50:48 pmSorry to hear about your power supply. Sometimes you hit and miss when buying low cost equipment. I considered a Twintex, but went for a Korad instead. It was much better documented on this blog. Dave made a couple of videos on this unit. Well, his Korad failed, but hey! At least I could see the insides.On a serious note, it was some kind of a design fault on older models.One of the ATX cases on my desk is indeed an ATX power supply with a couple of mods. The regular 5V, 12V outputs are there, of course, but I stacked in LM317 for variation. A little screen with voltage/current too. The other ATX case is a function generator with sine, square, triangle waves + lcd and controls. I had a few of those old ATX enclosures to mess with. Comes in handy for certain builds.