Hi all,
Thanks for the replies. Turns out my D1 was faulty, or becoming faulty. When I double-checked on the USB supply, it didn't work there either. Are they particularly static-sensitive?
The output of the converter goes to the 5V & GND pins on the D1, and also to the 5V and GND connectors on the LEDs. I use pin D2 of the Wemos to send data to the LEDs, via a 470 ohm resistor.
I specifically wanted to add the 12V to 5V converter because I plan to run these lights at the end of long wires (Xmas decorations), and was worried about voltage drop across the wires. Maybe it's a bit of overkill... when I checked, the lights work OK on 3.6V
Cheers, Frank
I've checked the voltages.... there's 12V going into the converter, and 5V coming out, and 5V across the 5V and GND pins on the D1 mini and across the LED supply, and the polarity is correct. I've only checked with a multimeter, but there doesn't seem to be any fluctuation in the 5V level. There does seem to be a momentary flash of the LEDs when the power is connected/disconnected.