10A CC/CV buck converter for led tests...

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viffer750
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10A CC/CV buck converter for led tests...

I got this from ebay: http://www.ebay.com/itm/181089352568?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

1

 

It’s a nice little buck converter, very good for testing leds and flashlights. If you have a power supply which is strong enough, you can build a voltage and current controlled test PS with a lot of potential for pennies. It’s not for professional use, but the ability of the converter is enough for a lot of tests. The efficiency is very good, does not generate too much heat, it can work without any additional  heatshink. I tested it at 30-40W for a long time, and the warmest components were only 50-60°C.

tested at 7.16A:

2

 

at 60Watt:

3

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mattthemuppet
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cool! Is that a passive GPU heatsink I see in the first test picture?

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viffer750
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mattthemuppet wrote:
cool! Is that a passive GPU heatsink I see in the first test picture?

yep, a zalman zm80d-hp Smile

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mattthemuppet
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damn, that’s a seriously fancy LED test bed heatsink Smile Takes me back to the day…

comfychair
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From a quick glance at the 'DC power supplies' category I spotted this: http://www.ebay.com/itm/130949993786

Only 2A capable, but for an actual application instead of test bench use, could be perfectly adequate. In particular I'm thinking of my current project using those '10W' 10-12v square LEDs for car interior lighting, and not really being happy with the typical 12v AC/DC drivers commonly used.

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2A would be great at 12-15V. Interesting find, and the price is certainly reasonable. Perhaps you could drive 2 of those 12V square LED’s in parallel @1A each. I wonder if that device could withstand voltage spikes while the car is running?

tivo532
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comfychair wrote:

From a quick glance at the ‘DC power supplies’ category I spotted this: http://www.ebay.com/itm/130949993786

Only 2A capable, but for an actual application instead of test bench use, could be perfectly adequate. In particular I’m thinking of my current project using those ‘10W’ 10-12v square LEDs for car interior lighting, and not really being happy with the typical 12v AC/DC drivers commonly used.

Nice one too! Can this be operated/wired in parallel? 2 to get 4A max? or 4 to get 8A Max? Beer
A Buy it now is around $1.54.

tivo532
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This seller has 10pcs 2A for $12.26. I’ll buy a set and will try. Beer

ryansoh3
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I guess this doesn’t apply too much for LED’s, but watch out for current spikes.

When we’re driving laser diodes, it was a PITA to find power supplies that would be noise free.

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dave_
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FlashPilot wrote:
I wonder if that device could withstand voltage spikes while the car is running?

They are clearly not made for this. If you do it, please add a proper fuse! (So if the chip dies and shorts out it doesn’t test how long your wiring can withstand the short circuit current of your battery+alternator. ;-))
comfychair
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So what IS the proper way to run one of those 10W LEDs in a car?

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Id like to know as well…

relic38
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Comfy, why not use the driver you have, or the other one I posted about in your thread? They should work in a car just fine I think, unless I’m missing something.
Tivo, that’s a great price on those modules! Putting them in parallel could be a problem. Make sure the output voltages match before connecting them together. Not sure if they are protected from reverse current flow.

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comfychair
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The drivers I have don't take kindly to the heat. In stock form they're just OK, but with an added resistor to get the output up from 700mA it starts flickering and not behaving nicely, and a 0 ohm resistor added in parallel with the original only upped output to 900mA. I would like something more robust.

tivo532
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relic38 wrote:
Tivo, that’s a great price on those modules! Putting them in parallel could be a problem. Make sure the output voltages match before connecting them together. Not sure if they are protected from reverse current flow.

Yes Relic! Number one in mind.
As for power supply, I remember I having this 12V/35A!

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relic38
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The one I tested had no flickering problem. Left it at 1A for 15 minutes or so. The chip got to 85C. Moght be worth a try, I think the larger components handle heat better and are more efficient.
sorry for sidetracking this thread Smile

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dave_
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comfychair wrote:

So what IS the proper way to run one of those 10W LEDs in a car?


The needed protection circuit is neither expensive nor complicated and looks usually somewhat like this:

-Choke to filter out high frequency noise which can irritate your regulator
-Transient voltage suppressor Diode to limit voltage
-Fuse to limit current if TVS diode triggers or something else happens
-Diode to block negative voltage spikes
That’s about the minimal protection for devices that are allowed to be powered with running engine.
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viffer750 wrote:

I got this from ebay: http://www.ebay.com/itm/181089352568?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649


Cr@p, doesn’t ship to my country, and we are neighbours!!!!
I would like DC-DC converter which I could adjust from about 0.90V to 8.40V with one fine potentiometer, doesn’t have to be 10A, 3A would suffice.

 

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I have something like this: http://www.ebay.com/itm/Green-LED-volt-meter-DC-DC-Step-down-Converter-Regulator-combine-2-in-1-/390401987125?pt=LH_DefaultDomain_0&hash=item5ae5c59235

Works pretty well, and I have added a cap to the output to smoothen the output current.

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Saved in my watch list Smile

 

relic38
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Sirius9. DX and FT have what you want. Voltage and current can be adjusted by trimpot. They seem to work well. They look very similar to the ones in the eBay links.

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viffer750
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Sirius9, choose one  Smile :

 http://www.ebay.com/sch/i.html?_odkw=DC-DC&LH_BIN=1&_sop=15&_osacat=117000&_from=R40&_trksid=p2045573.m570.l1313.TR10.TRC0.A0.Xconverter&_nkw=converter&_sacat=117000

 

 

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viffer750
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poor man's mini power supply, about for $30 Smile

1

not a beauty, right? Smile


but...

2

About 14-15A max current Cool,of course not for so long time. The little converter is very robust.




above 100W...

3

The bottleneck is the laptop power supply, the protection kicks in at about 105-110W. This is enough for almost everything.


Unfortunately there is a little problem with the current regulation. If the voltage is set to a high value, and if I connect a power led to it, the initial transient can kill the led, even if the current is set to a not too high value. So before I connect a led to the power supply, I have to check and set the voltage to a desirable value, this is below 5V in case of a single xm-l.

Apart from this, it is a very useful "tiny monster" power supply. :)




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Nice build viffer 750. Very creative.

 

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