Front end for current limited power supply for $5.00 US

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This step down power supply looks like it is programmable for current limiting: CLICK HERE It might be worth having a couple around if you need multiple supplies on a project.

 

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After looking at this board's photographs, I can see nothing that indicates that it is adjustable for either voltage or constant current.  There are no potentiometers anywhere on-board.   It is for turning +7-30V DC into +5V.

 

Search on ebay for a similar module.:  Potentiometer-adjustable voltage output with digital voltage display;  LM2596; DC-DC Buck Step Down Converter Module Voltage Regulator

 

I'm going out on a limb and say that the constant current section of a lab power supply is rarely used.  Constant current is used during the charging of Lithium-Ion batteries by the inexpensive TP4056-charging module board.  But that is the only time that I've seen it used.  However, a lab bench power supply isn't technically that without the constant current feature for component-level prototype design and testing.  I myself have never needed to use a constant-current feature.

Last Edited: Tue. Apr 5, 2016 - 10:48 PM
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Is it just me then but doesn't the description say:

DC-DC Step Down Power Supply Adjustable Module With LCD Display Without Housing Case

Output voltage: 0V~16.5V (Continuously adjustable)

What, I wonder, are the two tact switches on the board there for if it's not for interacting with some kind or UI to make adjustments?

 

The incredible thing here is that for $5 you wouldn't usually get anything but the LCD - how on earth do these Chinese do it and still make a profit??

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Follow the link in post #1 and scroll down, you'll find:

 

 

But I don't see any means of setting a current limit.

 

Last Edited: Tue. Apr 5, 2016 - 10:37 PM
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I didn't take a close look at the picture, just the specs:

 

Converter type: DC-DC
Input voltage: 5~23V (Best voltage 20V)
Output voltage: 0V~16.5V (Continuously adjustable)
Peak current: 3A
Mainboard size: 50mm x 30mm x 12mm(LxWxH)
Display module: STN LCD
LCD size: 37.5mm x 17.0mm(LxW)
LCD accuracy: 1%
Conversion efficiency: 95%
Load regulation S(I): <= 0.8%
Voltage regulation S(U): <= 0.8%

 

Voltage: Output voltage: 0V~16.5V (Continuously adjustable)

Current: Load regulation S(I): <= 0.8%

 

That says to me the voltage is adjustable as is the current. Now I have to buy one.

 

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Someguy22 wrote:

I didn't take a close look at the picture, just the specs:

 

Converter type: DC-DC
Input voltage: 5~23V (Best voltage 20V)
Output voltage: 0V~16.5V (Continuously adjustable)
Peak current: 3A
Mainboard size: 50mm x 30mm x 12mm(LxWxH)
Display module: STN LCD
LCD size: 37.5mm x 17.0mm(LxW)
LCD accuracy: 1%
Conversion efficiency: 95%
Load regulation S(I): <= 0.8%
Voltage regulation S(U): <= 0.8%

 

Voltage: Output voltage: 0V~16.5V (Continuously adjustable)

Current: Load regulation S(I): <= 0.8%

 

That says to me the voltage is adjustable as is the current. Now I have to buy one.

 

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clawson wrote:
The incredible thing here is that for $5 you wouldn't usually get anything but the LCD - how on earth do these Chinese do it and still make a profit??
That could be the title of a new thread all by itself.....

 

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

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"Current: Load regulation S(I): <= 0.8%" means that if you change the load in the range of near -maximum to near-minimum and/or vice-versa, then the regulated voltage on the load will change no more than 0.8%. 

 

It doesn't have anything to do with adjustable constant current.  

 

I would have never occurred to me to have push-buttons to adjust a programmable voltage

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Chinese junk used to mean a kind of ship, now it means a kind of shipment.

 

Never assume that any Chinese e-Bay description is 100% accurate.  Stuff can be from a production run where 2-3% randomly-sampled units failed testing and the customer requires no more than 1% failure. 

 

What to do?  Identify the problem for the next run and sell this run (the one with the 3% failure rate) as piece-units on eBay.  Include absolutely zero documentation so that you can 'save face' when it doesn't work in your customer's product on the other side of the world.

 

American and Canadian postal rates are so expensive because ordinary mail subsidizes junk-mail,  parcel shipment prices are used to subside ordinary mail, and all shipments overseas are sent by airmail.   Chinese post is so cheap because the items are stuffed into little envelopes, addressed electronically with bar-graphs, and stuffed into standard shipping containers.  The containers are then stacked on giant, giant ships which move as a constant conveyor belt between Hong Kong/Shenzhen and Long Beach, CA with about 10-14 days sea time.  From there the cost of USA shipment is handled by the US Postal Service.

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Do a search using google on these terms: "chinese trade agreement shipping usps" to find out why shipping from China to the US is essentially free. 

Edit to add: Ebay is involved. Where Aliexpress and Banggood come into play, I can not guess.

Last Edited: Tue. Apr 5, 2016 - 11:16 PM
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@Simonetta

IMO : a lab supply without adjustable currentlimit is a lousy lab supply.

And the Chinese boat is called a jonk, not junk cheeky

 

It is indeed incredible that the Chinese can produce at such low cost. I would say: enjoy it for the time it lasts.

I order quite often from both banggood and aliexpress and am very satisfied with quality, shipping costs wink and shipping time.

Of course I use common sense. If the spec says 5A for a Buck converter, and the wire on the inductor is 0.8mm, then I will test it at 5A (just to see of it releases smoke) but will never use it at that current. You are a sparkyor you are not.

 

Nard

A GIF is worth a thousend words   She is called Sylvia (2018), lives at Mint18.3 https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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On the subject of the current "performance"... a question was asked and answered by the Banggood staff member..

 

 

And they also stated that 3amps is the peak, 2.5 amps with good heat sinking (there isn't any) and 1.5 amps without heat sinking (as is delivered)

 

Ross McKenzie ValuSoft Melbourne Australia

Last Edited: Wed. Apr 6, 2016 - 03:25 AM
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Plons wrote:
And the Chinese boat is called a jonk, not junk cheeky

 

Nard, you might be challenged on that.

 

https://en.wikipedia.org/wiki/Ju...

 

aside: How is the eye recovering?

 

Cheers,

 

Ross

 

Ross McKenzie ValuSoft Melbourne Australia

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I'm going out on a limb and say that the constant current section of a lab power supply is rarely used.

 I use it all the time.  It also serves as a "current limit", so it's a safety feature for powering up new circuits.  And as you said, there is always battery charging...

 

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At times, I've found the current adjust very useful, though mostly, I have to admit, I just leave the current turned up to the full 2A of my ebay special PS from a few years ago.

 

"We trained hard... but it seemed that every time we were beginning to form up into a team, we would be reorganized. I was to learn later in life that we tend to meet any new situation by reorganizing. And a wonderful method it can be of creating the illusion of progress while producing confusion, inefficiency and demoralization." Petronius Arbiter, approx. 2000 years ago.

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valusoft wrote:

Plons wrote:

And the Chinese boat is called a jonk, not junk cheeky

 

 

Nard, you might be challenged on that.

 

https://en.wikipedia.org/wiki/Ju...

 

aside: How is the eye recovering?

 

Cheers,

 

Ross

 

 

I was referring to the Chinese spelling and pronounciation devil

(why do I get a spelling red underline on pronounciation ? )

 

Kidding aside: I stand corrected.

 

The eye is doing very good, but I have no glasses for the new combi. In 2 or 3 days the glasses should be ready.

The laptop and smartphone I can use, for a little while. The big PC's are a no go.

Looking forward to continue the Linux exploration.

 

Nard

 

A GIF is worth a thousend words   She is called Sylvia (2018), lives at Mint18.3 https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

Last Edited: Wed. Apr 6, 2016 - 02:46 PM
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(why do I get a spelling red underline on pronounciation ? )

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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Joey,

 

What site is that? Looks real interesting!

 

(BTW my mum was always a stickler for the pronunciation thing and would berate anyone caught using pronounciation!)

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It's just Google's own response to a search for 'Pronunciation', expanded by clicking on the chevron.

 

The image in my post is click-able, taking you to the above search results.

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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Oh my giddy aunt! I always use Google as my "dictionary" either for words I don't know or ones I want to check the spelling of. I just Google "define <word>" and there it is. In all that time and hundreds, if not thousands of lookups I have never clicked that chevron - Doh! surprise

 

Just to check it I just tried "define imbecile" (the way I'm feeling right now) and learnt something new from the etymology. I didn't know it really means "with a leg to stand on" (effectively ;-)

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Using Puppy Linux, I don't have my dictionaries at hand (Windows only).

So I used Google

 

http://www.mijnwoordenboek.nl/ve... snapshot

A lousy on-line dictionary that is: different spelling within the same paragraph crying

 

Okay. Learned another thing or two smiley

(or is it "Learnt another thing or two" ? Like Cliff's spelling )

 

Nard

 

 

 

A GIF is worth a thousend words   She is called Sylvia (2018), lives at Mint18.3 https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

Last Edited: Wed. Apr 6, 2016 - 10:19 PM