SinLoon USB Male with ON/Off Switch to Stripped Ends, USB 2.0 9-Speed Dimming Switch Power Cable, for LED Strips Little Table Lamp and Other 5V Devices 5PCS (1.5M/4.9FT)

I'm using this USB power cord with dimmer switch on a string of Fairy Lights (ASIN B013TEEKOK). I swapped out the CR2032 battery holder for this USB power cable. My main uses of the Fairy Lights and USB power cable is in dioramas, model making, and small displays. The estimated lifespan of the CR2032 is about 36 hours of continuous or total use. Even purchasing replacement batteries in bulk quantities aren't all that cheap if you have a lot of these in use (either personal use or as part of a gift or sale). Plus, most CR2032 battery holders on Fairy lights can be trouble because the compartments are often secured with VERY tiny screws and the contacts are very flimsy and fragile. This USB power cable replacement solves both issues. Since this USB power cable has a microcontroller inside the housing, I didn't need to worry about adding any resistors during my conversion. However, I did experiment a bit with no real benefit. You can (hopefully!) see tiny Surface Mounted resistors on both front and back sides of the PC board on my pics. I tested the converted unit using USB ports on separate PC desktop and laptop computers without issue. I also tested it on a surge protector with integrated USB ports and an Anker 10-port data hub (ASIN B00VDVCQ84 - yikes! A 67% price increase since I bought two). These also work as they should. Additionally, I have a spare cell phone charger wall wart that has a female USB port. This wall wart came with a cell phone from a few upgrades back. It's a Samsung OEM with an expected output of 5.0V DC and .7 amps. All my measurements were below these values. I haven't experienced any heat issues when the USB switch was set to its maximum output. The "dimmer" function has 9 steps but, I can only discern 4 or 5 steps. (For electronics sticklers out there, yes, I'm aware this is NOT technically correct. It's beyond this review to worry over.) At the dimmer end of the range, there is subtle yet noticeable rapid flashing - I just bump it up one step at a time until it looks steady. On the brightest end, I cannot discern any differences across the top 3 steps. Not a show stopper - these are Fairy Lights in models and dioramas. They work great. ******WARNING!******My surge protector and data hub have higher power output so, the lights are brighter, exhibit 9 discernible brightness levels, and do not exhibit any flashing at the dimmer end. ******WARNING!****** The output on my data hub (12V, 2.1 amps max) is WAY ABOVE the specs for my Fairy Lights (3V, .21 amp hours). There are no issues at the dimmer end but, at the higher end, LEDs started popping one by one and heat became dangerously high at the most distant end of the string. So, WATCH YOUR POWER SUPPLY SPECS FOR YOUR PARTICULAR APPLICATION! I'll stick to the wall wart with 5V, .7 amps until I figure out a safe solution. (I'll leave it to the purists to do the calculations and determine what the actual draw is.) Lastly, for those who may have issues with these not working with your LED strings, try swapping the poles. On the tiny Fairy Lights that I'm using, I used an eye loupe to see which side had the Anode and which had the Cathode. The RED (positive) goes to the Anode side, BLACK (negative) to the Cathode. If you get it wrong, the USB cable light will/may come on for a split second then cutoff. Disconnect the USB cable, swap the wires, reinsert the USB plug, hit the power on button. All in, these USB power cables are cost efficient and easy to install! Double check your power supply specs and your application requirements.

They all work great!

Works great. Since the dimmer function works by pulse width modulation rather than voltage control, the dimmer function works on "non-dimmable" LED strips.

They work great and save so much time because the switch is already in the cord.

Worked as described. A longer wire would be appreciated, but for the cost acceptable

I bought these for some light box projects I did for christmas. They have a few dimmable settings, and as long as you keep the usb powered, they have a memory of what brightness setting you left them on. The switch is also lit up a little bit so you can see it in the dark. I haven't had any issues with them yet!! They function very well for my application!

I operate a 3d printing service that makes a lot of lighted shadow box signs. Since we order a lot of these at a time, we have tried all the cheaper AliExpress offerings and some more expensive ones. However, we keep coming back to these for the value for money. We go through 30 to 40 of these a month and are extremely happy with them.

They are a great replacement dimmer , would be much better with matching shrink tubes