(12-Pcs) STMicroelectronics 3.3V, LD1117V33 Voltage Regulator, LD33V

Used these regulators to “fix” the China made ATi Rage PCI video cards reusing chips from server e-waste (that operate on 3.3 volt PCI slots only) for vintage computer use that only have 5 volt PCI slots, card had a convenient hole in it so I used a long bolt, washer, and nut as a heat sink, used shrink tube to protect the bolt, runs stone cold.

I used a heat sink also purchased on Amazon to dissipate heat from these stepping down 12-14 volts down to 3.3V. If you are tired of replacing AA/AAA or even CR2032 batteries, you can use the steady power from this instead. Does it obliterate the warranty? Yes. Is it worth it to not need to replace batteries? Yes. Since they might get hot, consider where you are putting them as to not burn yo skin. Not sure if they get that hot, but it is a consideration.

Function as specified

I was able to use these with a DC 5V supply, USB power bank, to run some colored LED lights for a Christmas Window display.

Work great, need a heat sink if major diffence between input voltage and 3.3V output

Hook it up and those pesky extra volts just disappear! Also has convenient warming technology that increases the temperature relative to the amount of extra power it's disappearing.You'll want to add the recommended capacitors if you care about voltage stability though.

Does the job. Using to drive high power LED at 3.3 v and 400 mA from a 5 v input. The chip gives a steady 3.3 v output. It gets a little warm but not blistering hot. I have attached a small 1 cm square heat sink using conductive tape. It's now barely warm to the touch. It's much cheaper than a step-down switching regulator and seems to work just as well.

Not much to say I'm putting 5V in and getting 3.3V out. Perfect.