Adjustable regulator modules

[debe]

This is the wave form on the DC output loaded 20mv/div vert. No load 5mv/div vert. With a 1000uf cap on output 5mv/div vert. Also one ive fitted to a VHF hand held tranciever to run it of 12v.

 

[kinarfi]

Here's a photo of one of these buck modules modified to be a LED driver, driving 3 watt LED at just under 700 ma, LED is rated for 800 ma, so it should last quite a while, I'll probably get to pass this on to my kids or grand kids.

 

[Nigel Goodwin]

OK, I've actually used a couple of the little regulators now, both on identical little boards, in order to provide external power to tutorial boards via the PICKit3 programmer connection. I've added a picture of the board (the socket connector strip also came from Bangood), a picture of it connected to an 16F1827 tutorial board (nothing there from Bangood), and also a picture of my new LCD tutorial board, using an LCD from Bangood.

 

[cct314]

Having used a number of those inexpensive Ebay switchers (w/out the metering) - some of which look exactly like the ones in the picture - I can say that they are certainly worth the price, which is less than that for which I can get the parts!

I did build one of these into a device that runs 24H/7D and noting that various parts of these ran "very warm" I:

- Paralleled high-quality, low-ESR capacitors (470uF) on the input and output sides to take some of the stress off the unknown (!) quality capacitors on these boards. (I used Panasonic caps, IIRC).

- Soldered a reasonably large piece of copper bent to an "L" shape to the tab of the IC (such as it is!) to improve heat-sinking.

- Using "JB-Weld" - a metal-filled epoxy capable of reasonably high temperatures, I attached a piece of aluminum bent to a "U" shape to the top of the inductor to get rid of some of its heat which was being transferred to its adjacent components.

Just adding the additional capacitors made a disproportional improvement in the reduction of the switching energy (like that on the pics from the CRO) on the input/output leads - more than you'd expect from the increase in capacitance - implying that the onboard units are probably a bit higher impedance than the new, outboard units. This may have meant that they would be dissipating a bit of heat on their own, probably resulting in reduced lifetime. For as cheap as they are, I wasn't counting on them having very good capacitors (or enough capacitance!) anyway!

My non-contact IR thermometer showed an approximate 10C drop in device temperature after adding the additional heat sinks. This cheap converter has been running 24/7 for about 2 years near its maximum ratings, so that's something!