Taidacent 5V Receiving Wireless Inductive Coil Wireless Charging Transmitter and Receiver Modules Wireless Charging Power Supply Module Induction Charging Module(5V1A)

This wireless power transfer kit turned out to be the perfect, contact-free solution for my hobby project, the world's first Nixie tube propeller clock. The coils are mounted on the component side of prototyping boards (with parallel traces on the other side, which cause no issues with the power transfer). The coils are approximately 8 mm from each other, which is the recommended distance. I ran some additional measurements, and found that in this configuration, the voltage begins to break down at around 400 mA of load current (my circuit only needs 140 mA, so I have more than enough margin), and the short current is 800 mA (but that is through the ammeter, which itself drops about 0.5 V). I also found that the coils allow an axis misalignment of up to 10 mm before the voltage starts breaking down at the 140 mA load.

I got these to power a small portable device. They work ok but you need to get the loops very close and then the power transfer is minimal. I needed to charge the battery much quicker than these were able to so I switched to a USB connection.

Don't buy these, they transmit pitifully low power and will not charge a phone.

Not useful. Could not even charge phone or anything I could plug into. It was supposed to do at least 1W at 5V and 1A but could barely get 0.5A.

These work great. Both delivered stable voltage.