[4-Pack] 5A DC-DC Adjustable Buck Converter 4~38v to 1.25-36v Step Down Power Supply High Efficiency Voltage Regulator Module ([4-Pack] 5a Buck)

Lo use para bajar un voltaje de 24 vdc a 12 vdc para el funcionamiento de un fan de 12 vdc

These seem to be a good value for the money, definitely cheaper and smaller than I could make myself. My application is as a DC filament voltage regulator in a vacuum tube audio amplifier.Each one of them was in a sealed gray smoke ESD bag, then those 4 were inside a larger gray smoke ESD bag (also sealed). This larger outer bag was wrapped in several layers of 1/4" bubble wrap, and then placed in a bubble envelope (that fit inside my cluster mailbox along with a copious amount of junk mail). So 5-Stars on packaging.I tested all 4 of them soon after opening the box they came in. I really needed only one at this time, but I couldn't pass up the discount on buying the 4-pack, as I know I'll use them real soon in other projects I have planned. As per other reviewers have said, I first turned the trim-pots counter-clockwise 10 revolutions on each one of them. Then one-by-one I hooked them up to a 0-28V 7.5A power supply, monitored the output on a calibrated Fluke 77BN multimeter, and I attached one of those Golden Metal-Fin(chassis mount) 10-ohm 25-W power resistor as a load (resulting in a 0.63A current being supplied by the little module) and this was a good test for my immediate application because I'll be using it on a tube that draws 0.6A at 6.3V for it's filament power.Each one when fired up with a 12V input, was putting out around 1.357volts with the trim-pot adjusted counter clockwise, so in that manner they were all identical. I then adjusted the trim-pot until I saw 6.3VDC on the Fluke multimeter. Then I changed the input voltage to 9V, and no change in the output. Then I changed the input voltage to 5V, and STILL no change in the 6.3V output under load! So these things, while sold as "DC-DC Buck Converters" can actually boost as well, at least from 5V input to 6.3V output as I tested them. Bonus happiness, so 5-Stars for that too. (I have forgotten to mention that on each of the 4 modules, I stuck the little heat-sink supplied onto each regulator chip before I began testing). Also I checked to see if the 6.3V output voltage would change if I removed the load resistor while the input voltage was applied; the answer is NO, not even by 1mV did the output change, regardless if the input voltage was 5, 9, or 12V, removing and inserting the load resistor had no effect on output voltage at all. So very stable, 5-Stars again.Since I was doing this testing at work, I had all day to test them, so after initially testing all 4 as described, I did a "burn-in" test for 2 hours on each one. The PCB itself (by touching the ground-plane on the back of the board, and the regulating chip's heat-sink were just barely perceptibly warmer than my finger's skin temperature after operating under load for 2 hours. The little toroid core (or the wire wrapped around it) WAS a bit warm after the 2-hour burn-in time, but not so warm as to make me want to withdraw my finger. But definitely warmer that the PCB board or the regulator chip. I can live with that.Next, I did what I had drawn in my schematic for my amplifier, which was place a 1,000uF 50V electrolytic cap across the output, along with a .01uF ceramic disc capacitor. (in my schematic I drew the electrolytic capacitor being right on the output of the module, and then a .01uF capacitor being right on the tube socket's filament pins). This being done, I hooked up a X1 probe to the load resistor and looked at ripple on a calibrated Tektronix 2246 Oscilloscope; ripple was basically nil with these two capacitor filters on the output (less than 0.5mV).So I'm satisfied that these will be quite useful for a DC Filament Regulator in my vacuum tube audio projects, and far superior to the LM338 5-Amp Linear regulator because of the much lower heat output - it's really orders of magnitude less heat than I got from the LM338 linear filament voltage regulators I have used in the past. So for my application, again 5-Stars.For those of you who don't think in "Metric" and whom are too lazy to open up another tab in their browsers to make use of a free Length Calculator, here are the dimensions: 2.125" L x 1.0"W x 0.625"H.Finally, I get so tired of so many of these Chinese products that claim you can use them (for example) at up to 32V input voltage BUT they only give you 35V-rated capacitors on the board. That's just piss-poor engineering, if they have 35V-rated capacitors, you'd best not be applying more than 24V or so (in order to have a comfortable margin of error. I am most PLEASED to tell you that both the input and output capacitors on this PCB are rated at 50V. One last, well deserved 5-Stars!I can't say how they'd perform at the full 5A load, because I didn't have the load resistors to do that. But on the other hand, in keeping with good engineering practice, I don't think I'd ask more than 2A (2.5A on a dare) out of these. You should never expect to get away with (long term) running any device at it's maximum current or voltage rating.I'm going to go ahead and use one of these in my current project, which is a metal box 8" x 8" x 8" (Hammond 1401E steel chassis with easy-to-machine aluminum front and rear panels) that has a mono 3.8W RMS all-triode Push-Pull amplifier in it driving a front-panel mounted Visaton FR8WP 3.3" Full-Range Driver 8 Ohm Speaker. There will be one of those handy front panel-mounted MP3/FLAC player modules, a volume and tone control - also a "Blend" control, that will allow me to continuously adjust the mix-down of left and right channel inputs to mono, so I can choose all left, all right, or a mix of both for my mono signal (depending or what sounds best with any particular source material). It uses a 12-Pin Compactron 6AC10 (3 hi-mu triodes in one envelope) for an SRPP pre-amp and the transformer (Hammond 125D) driven phase inverter ; and a 9-Pin 5687 dual twin med-mu triode for the push-pull output stage (Hammond 125H output transformer PRI=10K SEC=8 ohm). With 300V going to the 5687 you get a clean 3.8W maximum output from one tube. Step down the 300V to 260V for the phase inverter (with a 1N5311-1 constant current diode in the cathode), and step the 260V down to 240V for the SRPP pre-amp (with a 1N5311-1 constant current diode in the cathode). Total Hi-Fi it will not be, but that's not the application. It will be an 8" cube that lets me listen to audio books and Holy Qur'an readings. So in that application, the transformer's 150HZ to 15KHZ ratings match nicely with the speaker's 100HZ to 20KHZrating. Likewise the 3.8W output is a reasonable match to the speakers 15W maximum power limit, and the speakers 84db/1W/M sensitivity will make it plenty load enough for recliner side-table or bedroom end table listening. In fact, it'll probably also be plenty loud to fill a small room (8' x 8' or so) with sound loud enough to make conversation in a normal voice not possible.I'm going to use just one of these regulator modules for BOTH tube's filaments, that will be 1.5A of current drawn thru the device - comfortably within it's 5A rating. The way I'm going to mount this module is probably the way you ought to do so as well: it'll be mounted on a side or back wall of the enclosure with the trim-pot down and little heat-sink up. This way the module can cool naturally by convection, and the hot air rising will not be heating up the trim-pot (which is plastic and prone to melt or fail. Not that I anticipate (based on today's testing) that it will generate much heat, but better to plan ahead and be safe rather than sorry, no? This mounting attitude also allows airflow to rise across the module's rear ground plane (which radiates some of the regulator's heat).One final note, the two mounting holes in the module accommodate #4-40 hardware, but unless you have a low-profile nut for the top, you'd better use nylon nut there because it's rather close to the input and output solder tabs on the PCB's top. On the bottom, the mounting holes are surrounded by ground plane, so no worries there if you use metal stand-offs, nothing to short on the bottom.

Some of the competitors turn off if the voltage or current can't be met.I guess you want that in some cases.This one is simple. If the power source is not enough, this unit just decreases output in a linear fashion. If the power source goes back up (like a solar panel), then the unit steadily gets closer and then reaches the set voltage.

Junk.... one board was missing components, and the other boards mosfet blew once connected to power!Delivered promptly and packaged well on arrival though

Had to submerge lm2596's in mineral oil to keep cool after heatsinks couldn't hack it. Well inside 1.7 watts (spec says they can do 3) and they overheated.These beef supremes can easily exceed that and then some, well worth the upgrade recommend buying some more!