DC-DC Step Down Converter

NWCCTV

I think @erco or someone else posted this link a few weekes back but I could not find it. http://www.ebay.com/itm/1pcs-DC-DC-Buck-Converter-Step-Down-Module-LM2596-Power-Supply-Output-1-23V-30V-/251066005460?pt=LH_DefaultDomain_0&hash=item3a74b337d4

I just received the 4 I ordered a couple days ago and was so impressed I ordered 6 more. There's only 4 days left to get them for $1.78 and $1.00 shipping.

Mark_T

On the UK eBay site I found some similar modules in batches of 20 for just over £15 (free postage)! That's just over a dollar each, crazy.

NWCCTV

Is that free shipping to the US????? And I thought $1.78 was a deal!

Ron Czapala

I was impressed as well - have eleven of them now...

The LM2596S-ADJ no lead IC itself sells for over $4 at DigiKey or Jameco.

Not sure if the eBay unit is lead free

Mark_T

NWCCTV wrote: »

Is that free shipping to the US????? And I thought $1.78 was a deal!

Well it was on the .co.uk ebay site so can't say.

CuriousOne

I haven't used that particular model, but I bought similarily shaped step-up modules using LM2577. At loads greater than 1-2W, the IC and coil badly overheated, and thermal protection was shutting down the IC.

Martin Hodge

CuriousOne wrote: »

I haven't used that particular model, but I bought similarily shaped step-up modules using LM2577. At loads greater than 1-2W, the IC and coil badly overheated, and thermal protection was shutting down the IC.

If the pictures in the eBay ad are to be believed, the unit is capable of sourcing at least 12 watts.

Don M

I ordered 6 of these too. It's been over a week now so still waiting for them to arrive. They say 2 - 3 weeks... How long did it take for you to get them?

User Name

I ordered six of them from eBay seller "chip_partner" on the 22nd of January, and they arrived on the 1st of Feb. Paid $9 for the six, plus $1 freight.

I absolutely love them and use them constantly. Back-in-the-day, the average multi-turn pot was pretty lousy. They had a lot of backlash and it was difficult to target a specific setting. The pots they're putting on these boards are fabulous!

Depending on the supply voltage, the output of these units may wander a couple hundredths of a volt. That's the biggest criticism I can wage, and it's nothing.

NWCCTV

How long did it take for you to get them?

It was right at 3 weeks.

erco

The price of these buck converters has dropped to...

...you guessed it...

... a buck... $1.01 anyway.

http://www.ebay.com/itm/1-DC-DC-Buck-Converter-Step-Down-Module-LM2596-Power-Supply-Output-1-23V-30V-T7-/121208203049

erco

Here's a nice LM2596 board variant for $2.65: http://www.ebay.com/itm/1pc-DC-DC-LM2596-Step-down-Adjustable-Power-Supply-Module-CC-CV-LED-Driver-New-/131079838628

3 pots allow adjustment for CV & CC. Potential uses are battery chargers (multi type) and LED drivers. 3A max current

Gotta have one.

CuriousOne

I have both of them (the simple one and CC/CV).

Simple one, when giving 5V 1A from 12V input - heats quite much, input capacitor is burning hot.
CC/CV one - no matter what current limit you'll set, it will switch off if output current is more than 1.34A (12VDC input, 5VDC output).

So never going to order them again.

Here are exact URLs to ones I've purchased:

http://www.ebay.com/itm/111146952543?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

http://www.ebay.com/itm/DC-DC-Buck-Converter-Step-Down-Module-LM2596-Power-Supply-Output-1-23V-30V-/181227591312?pt=LH_DefaultDomain_0&hash=item2a32019690

erco

That's a bummer. Hopefully you got your money back. Nearly all of my Ebay finds work as advertised (always test upon receipt, before leaving feedback). If not, sellers are motivated to replace/refund.

CuriousOne

Not exactly DC/DC, but also should be noted:

http://www.ebay.com/itm/251210465283?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

These are cheapo cut-off wheels for dremel. They are cheap, yes, but they are weak, too. To cut one 1/8 screw, you need one such disk, it wears so fast! With genuine dremel disc, you can cut at least 5 pieces of 1/8 screws with it.

Ron Czapala

Pololu has a variety of DC to DC converters - some are pricey but probably more reliable...

http://www.pololu.com/category/84/regulators-and-power-supplies

CuriousOne

I bought this one also:

http://www.ebay.com/itm/150W-DC-DC-Boost-Converter-10-32V-to-12-35V-Step-Up-Voltage-Charger-Power-/121240568896?pt=LH_DefaultDomain_2&hash=item1c3a804440

It can't deliver full power under various conditions. For example, when generating 24V from 12V input, the maximum current you get is around 4A, which is less than stated 150W. Also, input capacitor heated so much, that it exploded.

User Name

Well, the instructions say that the board requires forced convection (think cooling fan) above 100W. A 24V output at around 4A is right at that limit.

CuriousOne

Yes, it was cooled for sure with heavy fan. The problem also is in fact, that say if input is 12v and output is 30V, max output current is about 2A.