septillion:
Biggest question, what was the rated voltage of the lights? Just connecting them to 8V and see they don’t blow right away isn’t very exactAnd is that wall wart AC or DC? Did you measure it? A low loaded AC wall wart (real transformer) can easily output 10V+.
These are the cheap Christmas tree lights which are in parallel/series. I’m in the US so 50 +50. I’m in the US so 120AC/170RMS. I believe the voltage drop/working voltage is 1.5 per light but can’t remember at the moment.
I connected the blubs to a variable power supply. At 1.5/2 volts DC about the same brightness as at 120vac. As I increased the voltage to 4 or 5 they appear to be the correct brightness. I suspect these bulbs are made for 220VAC and also sold in 120VAC market.
To my surprise the blubls would consistantly blow at about 8 volts. So I’m thinking driving them at 5VDC should not be a probelm. And for the most they’ve been working fine.
Wall wart is not a transformer, not heavy enough, there’s a chip in there.
I’m wondering if maybe I should add a resistor in series to drop the voltage a bit? Or a zener? Or maybe switch to 12v, and use a bcuk voltage reducer. And that will give me 12 to power the Arduino.