10Pack LM2596 DC to DC Buck Converter 3.0-40V to 1.5-35V Power Supply Step Down Module: Amazon.co.uk: Business, Industry & Science

Package arrived in good order but the contents are not as advertised. The DC Buck IC on these are not the LM2596 but the D2576. These produce higher output ripple (more noise) due to running at 56khz Vs 150khz of the LM2596.See photos. You would need to replace the output capacitor for a 1000 micF instead of the 220 micF on supplied board.They work but expensive for the the model. Deceptive marketing. Will not buy from this supplier again.

There are no instructions. The PCB is not double sided. i.e wanted to solder the power in wires on rather than relying on the screw terminals. Passed a tinned wire through the top and soldered the joint on the bottom. This doesn't work. You can only pass the wire from the bottom and solder the top to get a connection.For dialling in the output voltage, the tiny slotted screw has to be turned MANY rotations before it starts to register a change. I was going from 9.6v down to 5v and I must have rotated the screw anticlockwise 20 times before the output voltage changed.Once set up they are very good. I might put a blob of glue on the screw to prevent it from changing position.