Advice on cheap Lab Supply 30v 5amps seen all the stuff on ebay best quality?

[GiskardReventlov]

Some good new search terms for ebay!  I've seen systron-donner.  I've also seen Kepco and Kikusui.

[Electro Fan]

TTi is the real deal.  Don't know much about the others.  For anything over $100 I'd be looking for a power supply that can turn the output(s) on and off without using the main AC switch.

[dssence]

SO guys can anyone help me out if the HANTEK PPS2116A is indeed a linear power supply and not switching . I was going to go with that one. I couldn't find anything on ebay on 30v 5amps under 120 bucks on these brands
HP, Power Design, Sorensen, or Trigon.

[robrenz]

You obviously ignored my previous post in this thread.

Here it is again relisted  No one bid last time at $99.00 starting bid.  Contact the seller and offer him $80.00 as a buy it now price. If he agrees he can change the listing tell you when he is going to do it so you are ready to pounce on his buy it now price.

[Rigby]

If you want to wait until a make & model comes out that has zero problems in the field, you are going to wait forever.

I'm not sure why you're hell-bent on getting a new power supply over a used one.  Depending on your current needs --both amperage & timeframe-- there are plenty of very inexpensive supplies on eBay that work just fine.  I have bought two supplies on eBay, both of which said "Not working, for parts" and after reading the description I decided that I would pay $15 and try my luck.  In both cases I won the auctions and got supplies that work JUST FINE but have either a small cosmetic issue or simply weren't tested by the seller.  One is an HP 6286A, 0-20V, 0-10A, the other is a Power Designs 3650-S, 0-36V, 0-5A.  I designed a 3D printed a meter clip for the HP at home, printed it at work, and I adjust the voltage & current on the Power Designs supply with a multimeter connected.  Solved, for $100 total in purchase price and shipping, and I now have two excellent supplies.

I also have a Rigol DP832 that works great.  Yeah, you need to wire output 2 & 3 ground terminals together externally.  Yeah, there's a small output spike on each channel, but they are so short and have so little "oomph" behind them that I don't worry about it a lot.  I'm aware of it, though, and when I am doing work where a short small spike would cause damage, I just won't use that supply or I'll put a tiny cap in series or something.  As long as you KNOW the problem(s) that your supply has, it doesn't matter what the problems are.

Knowing the problems and knowing when/how to deal with them is far more important and far easier than finding a supply with no problems.

[nanofrog]

I'm not sure why you're hell-bent on getting a new power supply over a used one.

Wondering the same exact thing, as there are more than enough posts mentioning used over new that the OP should have noticed by now.

A case of Must have NEW fever perhaps? 

[dssence]

  hey thanks to all of you for helping out.  Honestly I wanted to have a new supply rather than risking myself with a used one. I know it might sound stupid, but I feel the hantek seems solid. Problem is I don't know if it's linear or a switched mode. I already sent a couple of emails to hantek waiting for them to reply.  Thanks again. Is there any difference on some of the supplies using a toroidal kind of transformer instead of a standard one ? how does it affect performance.

[Rigby]

  hey thanks to all of you for helping out.  Honestly I wanted to have a new supply rather than risking myself with a used one. I know it might sound stupid, but I feel the hantek seems solid. Problem is I don't know if it's linear or a switched mode. I already sent a couple of emails to hantek waiting for them to reply.  Thanks again. Is there any difference on some of the supplies using a toroidal kind of transformer instead of a standard one ? how does it affect performance.

You are worrying about the wrong things. 

Any respectable bench supply is going to be linear, probably.  If it's not, they're probably not a great supply manufacturer.  In truth it probably doesn't matter much if you're not going to use it for anything super delicate or of audiophool quality.  TVs and radios and computers all use switched power supplies in production.  Honestly, if it's that important, you could probably use a switched supply if you didn't mind regulating linearly between the power supply and the circuit you're building.

Toroidal transformers are more efficient, but they don't affect the output voltage when compared to traditional E I cores.  The output is rectified and linearly regulated so it won't matter much, if at all.

Hantek are absolute rubbish compared to an older HP supply.  The old designs are rock solid and rarely experience failure.  And when they do, you walk to your printer and look at the schematic you just printed and you find the part that went out.  You go to the computer, order a new one, and when it comes in you install it.  Fixed.  My HP 6286A has a massive, 50 year old 33000uf electrolytic cap in it that still cuts the mustard quite happily.  The variac in my Power Designs 3650-S still works just as well as it did when it was new.  The primary voltage adjustment is a damn variac of all things, coupled physically with a potentiometer.  Actually, maybe it's just a giant wire-wound high-wattage potentiometer, I don't know.  Schematic has been ordered and will be here this week.

Don't let 7-segment readouts get the best of you.  The new supplies just are not as good for a beginner.  Plain and simple.

[nanofrog]

  hey thanks to all of you for helping out.  Honestly I wanted to have a new supply rather than risking myself with a used one. I know it might sound stupid, but I feel the hantek seems solid. Problem is I don't know if it's linear or a switched mode. I already sent a couple of emails to hantek waiting for them to reply.  Thanks again. Is there any difference on some of the supplies using a toroidal kind of transformer instead of a standard one ? how does it affect performance.

I'm with Rigby. Definitely looking at this from the wrong perspective.

Simply put, the currently produced inexpensive Chinese offerings just aren't built anywhere near as solidly or reliably as the older, top quality used supplies that are available on places like eBay. Period.

Look at it this way... Those old beasts are still happily chugging along doing the job they were made for decades later. Do you seriously think that cheap Chinese station will make it anywhere near that long, given all the issues that have turned up already, and is occuring with multiple manufacturers?

Something to think about. 

[sync]

  hey thanks to all of you for helping out.  Honestly I wanted to have a new supply rather than risking myself with a used one.

That's a valid reason. But don't expect quality at these low prices.

Is Hantek the original manufacture or is it just rebanged?
Read the manual to get a first impression.
Search the internet for reviews and problems with this model.
Then you find this: https://www.eevblog.com/forum/testgear/hantek-power-supply-pps2116a-review/
Knowing that is also a Protek P6035, Vantek DPS 3305P or Quakko HY3005DP search again. You will find https://www.eevblog.com/forum/reviews/0-32v-0-5a-with-usb-control-protek-p6035-quakko-hy3005dp/. In this thread is a video

So this power supply is a killer. In a bad sense. It kills your projects.

Look for another power supply and do some research like written above.

[dssence]

  hey thanks to all of you for helping out.  Honestly I wanted to have a new supply rather than risking myself with a used one.

That's a valid reason. But don't expect quality at these low prices.

Is Hantek the original manufacture or is it just rebanged?
Read the manual to get a first impression.
Search the internet for reviews and problems with this model.
Then you find this: https://www.eevblog.com/forum/testgear/hantek-power-supply-pps2116a-review/
Knowing that is also a Protek P6035, Vantek DPS 3305P or Quakko HY3005DP search again. You will find https://www.eevblog.com/forum/reviews/0-32v-0-5a-with-usb-control-protek-p6035-quakko-hy3005dp/. In this thread is a video

So this power supply is a killer. In a bad sense. It kills your projects.

Look for another power supply and do some research like written above.

Hi thanks so much for worrying about my decision. SO what's this guy telling basically with the scope. That initially this supply instead of outputting 5 volts DC it's outputting 25 v instead of 5 volts?. How could this be possible ?. If these manufacturers are building supplies with this time specific milliseconds of outputting a different voltage than it's being setted up .
    Could this also apply to the hantek I'm going to buy. I honestly don't get it.

[Rigby]

Could this also apply to the hantek I'm going to buy. I honestly don't get it.

Yes.  Don't buy it.  Get something used, something that's been through a lot of use and came out still functioning.

HP.  Power Designs.  Agilent.  Hell, even Elenco or Heathkit.

Or, maybe the better course for you would be to use an ATX power supply and a linear regulator, if your current (amperage) requirements aren't high.  That is certainly the least expensive option and is the most flexible, it just requires a wee bit of know-how on how to do it.  It isn't hard.

[robrenz]

6 pages of advice and your not listening to us..... I give up 

[nanofrog]

6 pages of advice and your not listening to us..... I give up 

+1   

BTW, how do I unsubscribe from this thread?

[mrflibble]

yay! More old  HP PSU's on the market for me. 

Not that there's anything nearly as affordable for us Europeans ... Typically those nice HP PSU's are from the US and shipping kills it.

[sync]

SO what's this guy telling basically with the scope. That initially this supply instead of outputting 5 volts DC it's outputting 25 v instead of 5 volts?. How could this be possible ?

Two possibilities. The designers don't know what they are doing or they don't care.

[Rigby]

SO what's this guy telling basically with the scope. That initially this supply instead of outputting 5 volts DC it's outputting 25 v instead of 5 volts?. How could this be possible ?

Two possibilities. The designers don't know what they are doing or they don't care.

Or they are being instructed not to care, in order to cut costs.

[tikicarver]

I think it depends on which one you buy. I bought the Hantek PPS2116A  (32v/5amp) on Ebay.
It does not have the power spike like other ones people are talking about.
I got it for $99 on ebay from a dealer in Canada ( he already sold out, said will have more in April)

I checked it with a scope. First of all, it has an output On/OFF button and when you turn on the main power of the unit the output is always off. When turning on the output with the button, there is no spike, it goes to the selected voltage with no overshoot and when turning output off, there is also no spike, the voltage drops and looks like a cap discharging.
It also has computer control. Haven't played with that yet.
Looked inside and it as a large torriodal transformer
I am very happy with the PS.
I think you need to be careful when saying they are re-branded and all the same.

[dssence]

Yep damn I'm trying to get the hantek and this supplier from canada doesn't have anymore in stock. Any ideas in the US who might have hantek ?

[Electro Fan]

Question:  which is worse (harder on a test circuit):

a) a power supply turn on spike that goes +/-20 volts for 100us

or

b) a power supply turn on spike that goes +/- 2 volts for 1ms

or is it case dependent?

Thanks

[dssence]

I think what would states varies accordingly to the type of circuit you're testing. It it's a TTL cmos circuit it won't tolerate a huge difference you could fry the IC . Anyways to me it's not acceptable that a lab supply as soon as you shift the knob for voltage doesn't accomodate to the voltage you specify and overshoot.  Simple as that not acceptable. !

[dssence]

What about this supply it's atten

http://www.ebay.com/itm/Atten-TPR3005T-single-constant-voltage-constant-current-DC-power-supply-/110804972338

I couldn't find any reviews or if it's rebranded. Any ideas?

[rdl]

One problem buying cheap Chinese stuff is the lack of consistency. One batch may be fine, then for the next run the Chinese bean counters substitute half the parts with cheaper ones that don't work or fail early or have some other problem. It's a crap shoot. You might as well just flip a coin.

Buying a Korad from that SRA company on eBay seems pretty safe. They have a very good guarantee in case you have issues once you get it. The little 18 volt 3 amp job from Circuit Specialists also looks good, it's already so cheap I doubt anyone could change something to make it cheaper.

[dlt123me]

6 pages of advice and your not listening to us..... I give up 

After reading this thread and lurking around for awhile... I had to join the forum to give my thanks for everyone's advice in this thread... 

Just so you know, someone is listening.  I was going to get one of the Asian units that most are looking at, but after reading all the posts here suggesting used HP, Agilant and other older power supplies, I've decided to buy a used unit instead of one of the newer China made power supplies...

It makes sense, if they have been around all this time and still work, that says a lot..  I just won't have all the fancy push buttons, displays and programmed settings.   I want stability.

So, thanks to all of you who have suggested getting a used PS.  I get it now...   
Dennis

[dlt123me]

I don't have a power supply yet, but have been looking at used models of HP and other used PS's on eBay. 

Are these good specs for a triple output unit?

Output Ratings (Maximum current is derated 3.3% per °C from 40°C to 55°C)

Output 1: 0 to 6 V, 0 to 2.5 A
Output 2: 0 to +20 V, 0 to 0.5 A
Output 3: 0 to -20 V, 0 to 0.5 A
Power (max): 35 W
Ripple & Noise from 20 Hz to 20
---------------------

Are the amps too low?  It seems that .5A is way too low...  What would this power supply be used for?

Also, what good is having the ability to use 0 to -20Volts?  I'm new to electronics, and I have never heard of a negative volt.

Thanks,
Dennis