Old(er) vs new(er) bench power supplies?  - Page 1
Forum section: electronics / beginners

author: gsrokmix
author_rank: Contributor
timestamp: August 07, 2015, 09:42:59 pm
content: Hello all,This is my first post here on this forum. I have been lurking here, and watching Dave's videos for a while.I am 46 years old, and am returning to school to get an AS in electronics engineering technology. I had a successful career as a recording engineer for over 20 years. With the business drying up quite a bit after 9/11, I had to take a job in a factory (which I hate) about 5 years ago. Having always been fascinated by electronics, I've decided to learn seriously, and hopefully make a new career out of my passion.I am putting together my bench at home. I have a decent scope (Tek 2236), DMM (Fluke 87-V), function generator, and tools ect...I am now looking for a bench power supply.I have read a million posts, and seen lots of reviews about specific units. The factory I work at has probably a couple of hundred supplies in use. They are all BK. I've been looking at some used models such as the BK 1760 triple output supply, and BK 1735 single output supply. These can be had on average for about $150 each.My question (yes finally there is one.....) is are the older supplies still sufficient (assuming they are working properly) for general work? For about the same price as a new Mastech or other "cheap" supply on Amazon, I can get one of these older "lab quality" supplies.Am I missing something basic? The triple output supplies interest me because they can be chained for more voltage / current. I don't know that I would need more than 30V & 3A for awhile?I know this, or a very similar question(s) has been asked a million times, but I really would appreciate any advice or thoughts from those more experienced than myself (which is pretty much everyone here).Thanks for your time. I am excited to be a part of this community which is so rich with information!George

author: nanofrog
author_rank: Super Contributor
timestamp: August 07, 2015, 11:09:03 pm
content: Quote from: gsrokmix on August 07, 2015, 09:42:59 pmYes, IME.I've gotten better quality as well as more value for money by purchasing used. You do have to be careful of course, and do your homework (risk increases as you move down in price <untested, for-parts/not working, ...> vs. refurbished + calibrated + warranty type listings).Quote from: gsrokmix on August 07, 2015, 09:42:59 pmSome single output PSU's can be connected in series/parallel as well (i.e. HP 62xx series can IIRC). That said, I've found the multiple output models are a better value, so I'm a bit biased towards them.

author: BillW50
author_rank: Contributor
timestamp: August 07, 2015, 11:20:21 pm
content: I have one of these power supplies and I love them. Variable 32VDC, 5 amp supply for $57.88.http://www.banggood.com/CPS-3205-0-32V-0-5A-Portable-Adjustable-DC-Power-Supply-110V220V-p-934530.htmlAnd since the output is isolated, you can chain them without a problem.

author: gsrokmix
author_rank: Contributor
timestamp: August 08, 2015, 01:03:32 am
content: That Gopher unit looks interesting. Is it a switching supply?It looked like the multiple output supplies are a good value. I haven't read about a lot of people using them though?Thanks for the replies.George

author: nanofrog
author_rank: Super Contributor
timestamp: August 08, 2015, 05:12:50 am
content: Quote from: gsrokmix on August 08, 2015, 01:03:32 amYes, it's a switch mode design.There's an entire thread on it actually;Switching power supply Gopher CPS-3010 30V 10A $0.35/W, and even a a video review:Regarding multiple output PSU's, it seems there's plenty of people that have them (lots of photos in theShow your favorite and most used benchtop PSUthread). FWIW, mine would be a Power Designs TP343B.

author: JoeN
author_rank: Frequent Contributor
timestamp: August 08, 2015, 06:24:52 am
content: Go linear or go home.

author: nanofrog
author_rank: Super Contributor
timestamp: August 08, 2015, 07:07:49 am
content: Quote from: JoeN on August 08, 2015, 06:24:52 amI much prefer linear as well.And FWIW, older, quality used units available tend to be linear.

author: oldway
author_rank: Super Contributor
timestamp: August 08, 2015, 08:25:46 am
content: I recommend old HP power supplies.I have one 6236B triple output power supply and two 6296A (0-60V 3A).

author: george graves
author_rank: Super Contributor
timestamp: August 08, 2015, 08:39:25 am
content: Quote from: gsrokmix on August 07, 2015, 09:42:59 pmWelcome. I transitioned from video editing - so kinda the same deal (but started school for ME) For someone starting out, I would not recommend a used PS(or building your own PS). Reason? You won't have a clue how to repair it - once you've have a lot more knowledge, you will, but starting out, the best thing to do is to keep your barrier to entry low, and the frustration level manageable (cause it will be frustrating!)I like my little Korad units(KA3005P - I have 2 - might pick up a 3rd as a back up). Linear, really decent little guys - When I was starting electronics, I wish an entry level PS was as nice.Yes, older stuff will have higher quality....And when you get to that point that you know what you'll need, well, then you'll know that you need it. My 2 cents.Not to mention size. Do you have a huge desk that can take a 19" wide , 18" deep old PS? So yea, sometimes smaller is better.

author: rf-loop
author_rank: Super Contributor
timestamp: August 08, 2015, 08:41:16 am
content: Quote from: JoeN on August 08, 2015, 06:24:52 amFor normal lab use.There are three possibilities, linear, linear and linear1. Linear (conservative without any digital noise sources)2. Linear (with perhaps digital display (some times noise source, depends...)3. Linear using microproseccors control, TFT's ets digital noise sources but many times acceptable if know limits)..10. Very good lab grade "silent techcnology" primary switch mode, secondary analog...~~. crap cheap primary/secondary switch mode "laboratory" shit power supply

author: Rolo
author_rank: Regular Contributor
timestamp: August 08, 2015, 10:11:46 am
content: I had the same dilemma, if funds were no issue I would go for a Keysight U8001A or U8002A. I find this very attractive PSU's, linear and compact. While saving/waiting a used delta PSU showed up here (NL) on a second hand goods site.I made a digital meter for it and replaced the 20 turn pot. Now it's working fine and it fits my hobby needs perfectly.It's 0 to 30V, 3 Amps, linear. So it shows old ones can be good, if you can find a decent one to start with.

author: Joule Thief
author_rank: Regular Contributor
timestamp: August 08, 2015, 10:13:40 am
content: Quote from: oldway on August 08, 2015, 08:25:46 amI agree with the 62xx series from HP. A few squirts of contact cleaner on the VOLT / AMP selectors and maybe a filter capacitor or two in the reference power supplies and you have pure gold.Don't overlook the Power Design TP343A series. Years of use and the only items needing replacement are the VOLT / AMP switches and possibly a 10 turn voltage control pot.These are all absolutely silent runners and are a pleasure to work with.

author: GreyWoolfe
author_rank: Unknown
timestamp: August 08, 2015, 11:29:14 am
content: Don't forget the HP/Agilent/Keysight 36XX series power supplies. I have a 3610 that I like a lot.

author: BravoV
author_rank: Super Contributor
timestamp: August 08, 2015, 11:32:58 am
content: Since the OP live in US, if I were him, for start I'd stalk for HP 6114A or 6115A adj power supply.

author: Vgkid
author_rank: Super Contributor
timestamp: August 08, 2015, 02:33:47 pm
content: The 6114/6115 are pretty expensive, overkill for 99.9% of stuff. Plus they are sitting on my watch list...

author: zapta
author_rank: Super Contributor
timestamp: August 08, 2015, 05:01:33 pm
content: Quote from: GreyWoolfe on August 08, 2015, 11:29:14 amI have a E3610A in a good condition but switched to a compact Tenma switch mode power supply.Will not refuse a reasonable offer (US only). Established eevblog users can pay after delivery. It's just sitting there.

author: Vgkid
author_rank: Super Contributor
timestamp: August 08, 2015, 07:42:59 pm
content: Another thumbs up for those compact Tenma linear psu's. I have one powering a few ocxo's for several months. Just need to replace those caps.

author: gsrokmix
author_rank: Contributor
timestamp: August 09, 2015, 12:26:12 am
content: Thanks guys for all of the replies.The HP 6236B's look interesting. There are a few on ebay right now, but none look like they were tested.The Agilent 3610's look good as well.Will I really need 30V vs 20V out of a single supply?I appreciate all of the advice.Thanks,George

author: fivefish
author_rank: Frequent Contributor
timestamp: August 09, 2015, 02:52:49 am
content: My 2 cents to this discussion.What kind of projects do you think you'll be working on?If opamp based, then you need a dual power supply.500mA max of the HP 6236 (for the 0-20V sections) seems limiting/too low but will probably be enough for most opamp based projects.If you'll be mostly working on digital stuff (5V, 3.3V sufficient high amps... 3A-5A) will probably be more to your liking.I have a 6205C and used that for a long time, mostly on opamp based projects. But for other projects that require higher power, it goes into current limiting.I bought a GW Instek GPS-3303 power supply. All analog design, dual 0-30V, plus a dedicated 5V output, all 3Amps capable. I liked it so much, I bought (2) more dead PSUs on eBay for $50 each and for additional $10 in parts, fixed them all. So I have (3) of these GPS units in my lab, plus (2) HP power supplies (6205C, E3620A).There's currently one on eBay for $200.I suggest make an offer.http://www.ebay.com/itm/Nice-Instek-GPS-3303-Triple-Output-DC-Power-Supply-/131562897156?hash=item1ea1c27f04This sucker weighs in at 16lbs. Huge transformer, and will easily deliver it's rated output. I've load tested them, it's truly 6Amp capable @ 30V (180Watts) + (5V x 3A = 15W). Very easy to fix (jelly bean, cheap parts), and pretty robust.It doesn't have fancy push-button, set your output voltage, or USB connection. If you're after that, and you think you need those features, then look into something else. Maybe a new Rigol PSU.YMMV. Good luck.

author: c4757p
author_rank: Super Contributor
timestamp: August 09, 2015, 03:15:39 am
content: My $0.02: my school has a couple labs stocked with that model power supply. They survivestudents. Perfectly good PSU.

author: gsrokmix
author_rank: Contributor
timestamp: August 09, 2015, 03:19:03 am
content: Eventually I would like to build my own mic pre-amps, and other audio gear. I don't know what industry I may find work in once I get out of school. For the foreseable future I will be mainly using it to power pretty basic circuits I will be building to learn from. I am also starting to collect broken gear to be able to practice trying to repair.What do you feel the benefit of the Instek would be over an older unit such as a BK 1760?Thanks,George

author: gsrokmix
author_rank: Contributor
timestamp: August 09, 2015, 03:20:20 am
content: Which one you referring to, the Instek?

author: c4757p
author_rank: Super Contributor
timestamp: August 09, 2015, 03:58:17 am
content: Yes

author: fivefish
author_rank: Frequent Contributor
timestamp: August 09, 2015, 03:59:59 am
content: What do you feel the benefit of the Instek would be over an older unit such as a BK 1760?Right now, you can get the GPS unit for $200 on eBay (probably even less as the seller is asking for a Best offer price). Instek wins.I don't see a cooling fan on the BK psu, just a couple of big heatsinks at the back (maybe internal or none? I don't see a fan exhaust). The Instek has internal heatsinks, and an internal fan blowing hot air out (kicks in as temperature rises). So maybe the BK will be quieter than the Instek. or maybe the cooling fan of the Instek is a good sign of longevity? But then again, the BK is only 2amps per channel + 5Amps (9A total), while the Instek is 3Amps per channel x 3 outputs (9A total) -- draw(?) or slight win for Instek because of the fan.The BK doesn't have a separate current meter. The Instek have separate current and voltmeter for both outputs. (No voltmeter/currentmeter on fixed 5V output though). Instek for the win.More digits/resolution on the BK PSU LED display. BK for the win.The BK does have adjustable 3rd rail output (but no voltmeter), the Instek only has fixed 5V output (so voltmeter not needed). -- BK for the win.The BK only goes to 2 Amps on outputs A & B, the Instek to 3Amps on all outputs. Instek for the win.BK weighs at 21lbs, Instek at 16lbs. (as scrap metal, BK for the win. Carrying it around, Instek for the win)BK has coarse and fine voltage adjustments. The Instek needs light-finger touch if you want to set voltage/current to exactly 15.00 (so you don't get 14.99, or 15.01). BK wins.Bigger LED displays for the Instek. And the separate current meter is a big-PLUS for me. I can monitor voltage and current at the same time at a glance. Instek for the win.Sorry, but it's an ugly power switch on the BK PSUIt looks so out of place with the rest of it's knobs and buttons.Both PSUs can do independent, series or parallel connection of it's dual outputs. -- draw.** The only thing I don't like about the Instek is their use of single-turn potentiometers for the voltage and current setting. A multi-turn potentiometer would have been nice since it doesnt have fine/coarse adjustments.Both seems a good pick for a lab PSU. Overall, my *personal* bias is towards the Instek because of that separate current meters, higher 3A+3A+3A capability... plus I know how to fix these things if ever they die out on me.

author: gsrokmix
author_rank: Contributor
timestamp: August 09, 2015, 05:11:48 am
content: Thanks fivefish. You made some good points. Thanks for taking the time to makethe comparisons.I suppose the age of both could be considered too. Many more hours of run time on the older BK units I would have to assume?

author: codeboy2k
author_rank: Super Contributor
timestamp: August 09, 2015, 09:13:19 am
content: Quote from: Joule Thief on August 08, 2015, 10:13:40 amYou can also get some individual Power Designs PSUs for $25 to $50 on eBay sometimes. So for $150 max plus shipping you might get 3 great (but individual) supplies. Don't overlook this either.There is an advantage to having individual supplies rather than 1 big one with multiple outputs. If one supply fails you still have two others. However, if something goes wrong in your triple output supply, you're down for a while.

author: Gyro
author_rank: Super Contributor
timestamp: August 09, 2015, 10:09:26 am
content: I don't have any knowledge of the BK but have a GPS2303 so can offer some inputs...QuoteThe large rear heatsinks on the BK should be rated for full load with just convection cooling, but will get very hot in the process. The internal heatsinks on the Instek are much smaller (surprisingly so and PCB mounted) and are completely reliant on the fan cooling and any reasonable load. Seems to work well in practice (seems bulletproof) but will obviously be noisier at high load, but much less at risk from blocked convection airflow (stacking books on top etc). The majority of the weight in the Instek is the big torroidal transformer, not cooling hardware. It also uses transformer tapping relays to minimise the heat disipation - you hear these click as the voltage is adjusted, again a sensible design idea and appears to work well without glitching.QuoteThe Instek has single turn pots, reasonably easy to adjust to 0.1V, very fiddly to get to 0.01V - ie. its display resolution is a reasonable match for setting accuracy. Don't know about the BK.QuoteThe Series / parallel options are really useful on the Instek for getting lower voltage higher current, higher voltage lower current, or dual tracking supplies. The output terminals are automatically switched and the slave channel automatically follows the master to ensure equal voltage and current sharing. Of course you can connect them as you want for individual adjustment too. I doubt if the 3303 is designed for paralleling the 5V too to get 9A, but I suppose it might work if you adjust the other channels very carefully - not sure what would happen if you tried to pump 30V @ 6A into the 5V outputNothing good at a guessEdit: I'd be surprised if someone hadn't tried that at school mind you!

author: fivefish
author_rank: Frequent Contributor
timestamp: August 09, 2015, 11:55:10 am
content: Right. Good inputs. Yes, the multiple tapping depending on your output voltage setting keeps heat dissipation at minimum required.I'd be surprised if someone hadn't tried that at school mind you!The 3 channels all have floating outputs, so technically, you can set CH A & B to 5V, parallel it with the fixed 5V output, and get 5V @ 9Amps (3A x 3 in parallel)... if you need that.Also have to add that the operation of the voltmeter and ammeter displays are totally separate from the PSU operation. i.e. your voltmeter and ammeter can be busted and the PSU will still operate normally (just have to use an external multimeter). Replace the busted AD converter chips with a compatible ICL7107 (cost $0.60 on eBay) and you're back in business.On the Instek, I've load tested the 2 channel outputs (A & B) at it's max operating Volts/Amps over 1+ hour continuous and it survived. No problems at all. --- actually, I was testing my DIY Electronic Load. Both my PSU and DIY Eload survived at 60V @ 3A, or 30V @ 6A.I don't see a separate DC Outputs ON/OFF switch on the BK. So Instek for the win in this area.I'm sure the BK can also do it, but I've also personally tried series operating (2) Instek units, to get 120Volts DC @ 3Amps, or 60V @ 6Amps. No problems.

author: rastro
author_rank: Frequent Contributor
timestamp: August 09, 2015, 03:35:46 pm
content: I have both BK 1760 & HP 6236B. They are both great linear supplies.Pluses:- Both are air cooled no fan noise.- Schematics freely available on line.- HP 6236B is fairly compact.Minuses:- HP 6236B has some audible 60Hz noise from the large transformer.- HP 6236B does not have adjustable current limiting feature - crow bar maximum current only.- BK 1760 takes up a fair amount of room on bench compared to newer switch mode power supplies.- Manual control onlyWith some patients you can find both unit on eBay for under $100.00

author: Vgkid
author_rank: Super Contributor
timestamp: August 10, 2015, 01:57:13 am
content: Another good option are Lambda power supplies.

author: gsrokmix
author_rank: Contributor
timestamp: August 10, 2015, 07:58:08 pm
content: Well I decided to go with the Instek supply. I'll have a go with it & see how it is. It seems to get good reviews from what I've read, minus the single turn pots which people don't really like for their low resolution.There seems to be no shortage of all of the older BK & other units out there, so if this newer supply doesn't work out for me, I'll start hunting again.Thanks very much to everyone for their advice, I really appreciate it.George

author: JoeN
author_rank: Frequent Contributor
timestamp: August 24, 2015, 06:12:07 am
content: Quote from: fivefish on August 09, 2015, 02:52:49 amThat looks a lot like the first power supply I bought. Mine is badged Mastech-HY3005F but it looks the same, otherwise 30V 2 channels, one 5A channel, same parallel/series/independent switching, etc. It's worked great for me over the last 3 years. Got it for $200 and that is still the price.http://www.amazon.com/Mastech-HY3005F-3Triple-Linear-Power-Supply/dp/B004ISD7T6http://www.testequipmentdepot.com/instek/powersupplies/linear-dc-power-supply-gps-3303.htmInstek's 2303 model, you pay less because of the spelling error. Actually, they even got the model number wrong. I'm sure they fixed that by now. Maybe that was an early image they sent to Amazon. Still, I think it's funny.

author: fivefish
author_rank: Frequent Contributor
timestamp: August 24, 2015, 06:31:21 am
content: LOL That is funny.Anyways, the 3303 looks like this. No typos.It may look similar on the outside, but the guts/internal design are totally different between Mastech and Instek

author: JoeN
author_rank: Frequent Contributor
timestamp: August 24, 2015, 06:59:28 am
content: Are those big LED driver ICs ICL7107s? If so, Maxim, Intersil, Microchip or some unknown clone company?

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: August 24, 2015, 02:51:02 pm
content: I will second Lamdas as great starting supplies. I got a couple triple output LPT-7202-FM models. Sure, they have analog meters, but they are faster to note a change with (slower to read the exact values). They are very solid, and silent save for a hint of hum. I have one of units with two of the three supplies wired for auto-tracking so I get matching voltages for use as positive and negative supplies for op amp circuits. They are floating ground unless you connect the earth ground; so no ground loop worries. I got mine for around $35 plus shipping. I think they each had a broken binding post, which cost 20 cents and ten minutes to fix. The prices vary a lot, but if you look around you can often find them cheaper, or make an offer. Remember, you are getting three supplies in one. If they don't work, or put out less than rated current, I can tell you which capacitors you typically need to replace. Easy, through hole boards.I also have one Acopian dual supply, which is nice, but having a single meter for volts and amps for each supply is really annoying, and possibly dangerous to your circuit. You want it on amps when you are testing things, but you also want to see that you have the volts set correctly. I would highly recommend your supply have a separate volt meter and ammeter.You will really end up wanting at least two or three supplies, possibly more.

author: fivefish
author_rank: Frequent Contributor
timestamp: August 24, 2015, 05:15:13 pm
content: Quote from: JoeN on August 24, 2015, 06:59:28 amIt was a different part# (not 7107)... I can't remember anymore, the part# costs $25-$30 on eBay.But I replaced it with an ICL7107 ($0.75) and it works the same.