RioRand LM2596 DC-DC Buck Converter Step Down Module Power Supply Output 1.23V-30V (5Pcs-LM2596)

Rarely do I give a product 5 stars but this item is the exception. What struck me right from the start was the professional packaging for each board. They were individually sealed in an anti-static bag. I've gotten electronics (LASERS, 365 nm UV LEDs, etc) that have either been shipped in a plain plastic baggie or just in a shipping envelope. Then there is the price. Less than $2 per piece! I had originally intended to build an adjustable regulator based on the LM2576-adj; however, this board is exactly what I need for a lab supply I am building and will also go into a solar cell battery charger.As to the devices performance under load I modified one unit by replacing the output cap with a 1000 uF 35v cap and also used Arctic Alumina thermally conductive epoxy to glue a Cosmos copper RAM heatsink to both of them both available via Amazon. (see attached pic) One word of caution - Arctic Alumina gels after 3 minutes and is rock hard after 5 so work quickly bearing in mind that once the epoxy sets the heatsink isn't going to come off without destruction. I hooked the unmodified device up to my scope and attached a homemade dynamic load to the output terminals. The open circuit voltage was set to 12.6v. With a 1 ma load there were 3 usec pulses impressed on the DC output @ 56 KHz. Pk-pk amplitude was 64 mv. @ 1.5 amps the pk-pk amplitude rose to 134 mv with a 6.4 usec pulse width. The one with the 1000 uf cap at 1 ma had a pulse width of 2.8 usec and a pk-pk amplitude of 16 mv. At 1.5 amps the pulse width widened to 7.8 usec with a pk-pk amplitude of 33 mv. A vast improvement over the unmodded version. Both versions lost regulation at about 1.75 amps which I attribute to the time constant of the DC supply I am using. (18 v pk-pk fullwave rectified into a 4700 uf cap) I had noticed that while my load got significantly hot the regulator was only a couple of degrees above ambient so adding the heatsink might be overkill. Since I am building a lab supply and want the output as clean as possible I will mod the other board and use a low pass filter on the output of each board. Caveat: NatSemi's data sheet doesn't recommend going over 820 uf for the output cap. I believe it's because too large a cap might inhibit starting as it looks like a very low impedance at power up. I didn't notice any problems.I am extremely satisfied with the boards performance and would recommend it to anyone looking for a cheap reliable regulator board. However, depending on the application, one may not need to mod the board. Bear in mind that the negative lead of the output cap is soldered to the ground plane and is difficult to clear of solder. I've got years of soldering skills both with thru hole and surface mount devices and clearing the ground hole took a little bit of effort. I would also recommend, if you decide to use Arctic Alumina thermal epoxy, that you download the MSDS and application instructions from their web site.Update 30 Oct: 16: I modified two modules changing the output cap to 1000 uF and removing the trim pot so I could use a panel mounted pot to control the output. Since the pot was located about 4 inches from the board I used shielded RG218 mini-coax to connect the board to the pot minimizing stray fields from influencing the units stability. I wanted the power switch on the front panel but was concerned about running the hot side of the line past the regulators. That issue was avoided by twisting the wires and dressing them close to the chassis and then covered them with conductive copper tape to further shield the wires. Below are two views of the finished power supply. The front panel turned out real well and internally the layout is neatly done. Most of the parts can be obtained from Amazon. The panel meters are Hopesun 15 volt D'Arsonval movement analog meters. I used them because they don't require a power supply and, if I need precision, I can use my DVM. The unit cost me about $60 to build as compared to over $200 bucks for a decent lab supply of similar performance. All parts are new. I originally wanted a multi-turn pot to control the voltage but a 10 turn pot would have set me back $10.00; the 1 turn pot cost me a little over $1.00 and is precise enough for my needs. For really precision voltages I have a device I designed that uses 10 turn pots and a precision op-amp circuit that is stable to to .1 mv which makes it great for testing open loop op-amp gain. Anyway, I am really pleased with the supply. It will source 1500 ma up to 12 volts. At around 15 volts the current drops to about 750 ma since the transformers I am using only give a filtered output at 21 volts. The current draw at 15 volts starts to overwhelm the time constant of the filters. No biggie. However, I probably should have used bigger transformers but that would have added to the weight and would have crowded the layout. The goal of this project was to construct a unit with two isolated supplies that would emulate a differential power source while not breaking the bank since most designs I am working on utilize a +/- supply. I'd be more than happy to provide a BOM, a schematic, and construction notes if anyone is interested.

Allows you to adjust desired output voltage

This product does as intended in that it allows you to vary the voltage from what comes in to output. However the adjustment is spotty and doesn't seem to work all the time. I'm still testing and hope I can find a happy medium for the adjustment so I can use this to reduce the voltage on a small solar panel. Build quality seems pretty good.

Like several others, I wanted to hook this up to a raspberry pi. I put the the pi in a case with a small LCD screen, which required a 7-12v source, so by grabbing a 12V 1A wall wart and setting one of these to 5v for the pi, they both run flawlessly. And since it's not dumping a good amount of waste heat like a linear regulator, they work well in enclosed cases.They also work well as small adjustable bench supplies for odd voltages that aren't the typical 12v/5v/3.3v that the PC power supply I'm using puts out. Adjustable to the 1/100th of a volt with a steady hand. Just solder on a couple wire leads, the two for the input go onto the 12v rail of the power supply, the two outputs go onto a breadboard. And at $2 a pop, I'm not as worried about breaking them as I would be about a $200-$300 true adjustable bench supply. Having one would still be nice though.

Works well enough for the money, but item isn't as advertised. Capacitors are not Sanyo, nor are they solid caps like pictured in the listing.

the only reason i did not give it 5 stars was because i did have to re-solder the potentiometer on one of the five pieces i received. it was a quick fix but it took a lot of troubleshooting to figure that out. these regulators are great for the price and they work very well even at very low voltage (5.0 to 8.4 volts). they are easily adjustable by the hundredth of a volt at 8.4 volts and adjust easily by the tenth of a volt above 12 volts. All my voltage checks were done at 2.0 amp and below. lowest efficiency by my tests was 72% at 5 volts and the highest efficiency that i tested was 89% at 30 volts. they perform well for a very cheap unit. I used this model in a variable voltage e-cigarette box mod and would reccomend these to anyone needing low amperage voltage regulation. actual size is 2.3 inches x 1.1 inches by 0.7 inches.

These modules really need QC - Test before you power a live circuit!Of the five modules I reviewed, two won't hold a steady voltage (it wavers by ~100mV +/-); One blew up on power application (like fire starting blow up);Under overload (12V output into a 3ohm 50W resistor = 4A out), they die safely, but do not recover. True LM2596 chips are supposed to feature overload and thermal protection circuits, these do not appear to have such safeguards.(Testing conditions = 33.4V input (8S Lipo))

I got the five pack and am glad I did, because I'm constantly finding new uses for the LM2596. Thank you to the reviewer who pointed out you have to keep turning the little screw until you see results -- I was almost ready to return these as having no function at all until I went back, read that review, and just gave it a few dozen more turns. Now that I'm in the "sweet spot" it's pretty easy to get to exactly where you want. I'm going to try replacing the tiny pot with a much larger one designed for human fingers rather than tiny screwdrivers, but frankly, I'm amazed at what a couple bucks as got me. I'm just starting to get serious about electronics, and one thing I've learned is that the more you deal with board-level components rather than full systems, you can't assume a device that asks for 5v will also work with 6v or 9v or whatever you happen to have laying around. I've fried enough peripherals by now to really appreciate the option of providing exactly the voltage that's specified.