Buying a power supply - Page 1
Forum section: electronics / beginners

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: November 16, 2012, 02:12:46 am
content: I am going to buy a power supply and I have read around that Mastech Power supply are pretty good .. So I picked 2 different ones and wanted your opinion between or if you can suggest something different please let me know...MASTECH HY1803DAdjustable outputs: 0-18V and 0-3AVariable controls for both current and voltage outputsInput voltage: 110V/60Hz and 220V/50Hz SwitchableLine regulation: CV <= 0.01% + 1 mV, CC <= 0.2% + 1 mALoad Regulation: CV <= 0.01% + 3mV, CC <= 0.2% + 3 mARipple noise: CV <= 0.5 mV RMS, CC <= 3 mA RMSProtection: constant current and short-circuit protectionLCD reading accuracy: +/-1% for voltage and +/-2% for currentEnvironment: 0-40C, relative humidity < 90%Size: 9" x 6.8" x 3.7"Weight: 10 lbsPrice -$70Also is backlightedVSMASTECH HY1502DOutput Voltage : 0- 15V @ 2AOutput Current :0-2 AInput Voltage: 110V 60Hz + 220V 50HzConstant voltage/ Constant CurrentVoltage and Current adjustmentPower effect: CV<0.01%+1mV, CC<0.2% + 1mAOverload effect: CV<0.01% +3mV, CC<0.2% +3mAWaves and noises: CV<0.5mV r.m.s, CC 3mA, r.m.sProtection: High current limited.Ripple & Noise: <1mV rmsOutput Current: 0-2 AOperating Temperature : 0 - 102 F ( 0 -40 C), Relative Humidity: <90%Meter Accuracy is within + or - 2.5%Size: 9 x 6 3/4 x 3 3/4"Weight: 7 lbs6 month warrantyPrice - $50No backlightThanksJAy

author: alanb
author_rank: Frequent Contributor
timestamp: November 16, 2012, 02:14:20 pm
content: You don't specify what you need the PSU for, as they have different maximum and minimum voltage and current capabilities it is up to you to decide if its worth paying the difference and getting higher capabilities.There appears to be different terminology used on the two sets of specifications which may cause confusion. Power effect on the second is probably the same as line regulation on the first and overload effect is probably the same as load regulation.As far Mastech is concerned they appear reasonably well made and good value for money, however they cannot be compared to the high end supplies like Thurlby Thandar which would probably cost 3 - 4 times as much for the same voltage and current.

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: November 16, 2012, 04:25:45 pm
content: Well problem is that I just need a power supply so I can test circuits that I repair without pulling several different wall power supplies in order to find the right one ...

author: T4P
author_rank: Super Contributor
timestamp: November 16, 2012, 07:11:49 pm
content: All you need then is one with two 30V/3A outputs as well as a 5V/2A or 3A outputBuy the Mastechs, avoid the rest and certainly none of the cheaper crap on farnell/newark/element14Or a 5amp model if you can afford.

author: DavidDLC
author_rank: Frequent Contributor
timestamp: November 16, 2012, 07:27:47 pm
content: My recommendation is to get two power supplies if you can now.There is going to be a time, when you need more than one voltage level to be used.David.

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: November 20, 2012, 02:06:46 pm
content: Well here what I picked upMASTECH DC POWER SUPPLY HY3003D **MUST SEE** MINT CONDITIONhttp://www.ebay.com/itm/230874163168?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

author: saturation
author_rank: Super Contributor
timestamp: November 20, 2012, 02:16:18 pm
content: It looks decent, could you tear it down and take photos? Curious to see what it looks like inside, if the quality control is still good. Its also good to performance test it, at least check for overshoot on power on, the short circuit protection or setting constant current settings with zero volt output.

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: November 20, 2012, 02:51:07 pm
content: Quote from: saturation on November 20, 2012, 02:16:18 pmI will take lots of pictures and will do as many test that I can...Oh do you think that's a good price for the unit?

author: saturation
author_rank: Super Contributor
timestamp: November 20, 2012, 04:17:13 pm
content: Yes, if it works well and chances are good it will be because the vendor you choose has 100% satisfaction with over 6000 sales since 1999; I've add them to my preferred sellers.I presume its used but in mint shape? New, they run about $100, plus delivery. It very common for many eevblog buyers to base their judgment on their external appearance and buttons, its more vital to get it to perform properly; and its rarely discussed by sellers, so always good to give them a test through.I own the LED version, the 3030D.Quote from: TorqueRanger on November 20, 2012, 02:51:07 pm

author: OndraSter
author_rank: Contributor
timestamp: November 20, 2012, 07:03:14 pm
content: The chassis looks exactly like my one-hung-low Chinese brand.One sentence that explains how awesome the PSU is:"There is an earth binding post on the front yet there are only 2 wires going to the wall socket."If anybody wants any pictures I can take them tomorrow.

author: saturation
author_rank: Super Contributor
timestamp: November 20, 2012, 08:01:34 pm
content: These PSU all look similar, that's why what's inside that counts. Also the 2 terminal ones are often not suitable for true electronics use. Even the 3 terminal one's can iffy, so far only true Mastech one's are the least likely to be problem.https://www.eevblog.com/forum/product-reviews-photos-and-discussion/beware-yihua-yh-305d-bench-psu/?nowapQuote from: OndraSter on November 20, 2012, 07:03:14 pm

author: 0xCDCDCDCD
author_rank: Newbie
timestamp: November 22, 2012, 01:02:24 am
content: Is there anyone who know if there is somehow a way to buy one in Canada? (Or if someone know other companies/power supplies which are in sale overhere?)I'm looking for one and I just find some made in china (or cheap one) for like 160-180$... excluding tax and shipping (about 40$)... Even eBay isn't on my side !

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: November 22, 2012, 01:30:51 am
content: Quote from: 0xCDCDCDCD on November 22, 2012, 01:02:24 amI just helped another forum member sourced two Caltek DPS3305P power supplies from China in another thread, and they are on their way to Canada as we speak.https://www.eevblog.com/forum/buysellwanted/wtb-source-for-vantekcaltek-dsp3305p-$100-reward/I'm in Hong Kong so generally I can help with anything Chinese made.

author: ptricks
author_rank: Frequent Contributor
timestamp: November 22, 2012, 02:26:56 pm
content: The mastech supplies are basic linear designs. Usually 741 or 324 op amps with 2n3055 pass transistors.The rest is just transformer, case and the displays.Seriously consider building your own , most of the low end supplies are basic components ,which is fine , but the quality of the implementation is poor.

author: andyturk
author_rank: Frequent Contributor
timestamp: November 23, 2012, 06:29:53 am
content: For what it's worth, I just picked up a usedBK Precision 1651. It's not the latest and greatest, but seems to work pretty well. Ripple is low, it doesn't overshoot and the meters are close enough. It's fairly compact and doesn't take up a lot of space on my small desk. It was $99.

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: November 24, 2012, 03:36:20 am
content: Quote from: ptricks on November 22, 2012, 02:26:56 pmWell here is my thread on building a power supply and that went no where really quick...https://www.eevblog.com/forum/beginners/benchtop-power-supply/msg162285/#msg162285So I found a guy on ebay with this power supply for $50 bucks and figured hell for that price I can't go wrong ... I also figured if something goes wrong I will fix it and possible upgrade parts when felt necessary ..

author: NEDM64
author_rank: Contributor
timestamp: November 24, 2012, 05:06:43 am
content: Quote from: TorqueRanger on November 24, 2012, 03:36:20 amI needed a PSU real quick, but didn't want to spend a little for a single out PSU which wouldn't do for me, neither a lot for a dual output low-end PSU...I had a 15V 60VA center tapped transformer lying about too, so I bought a LM317/LM337 kit from a local store, soldered it and voilá... it's very basic, but it works! And it didn't break the bank...Now, I'm improving on the PCB and doing one with current limiting, 5A output, and microprocessor monitoring and control.

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: November 27, 2012, 11:53:46 pm
content: I got the power supply today and it looks almost brand new and there is little to no wear on it and as soon as I find my camera I will be posting up pics and a break down too ..