The Flexible Filament LED
This style has been available for years in consumer bulbs. But recently these 3V versions have become available. Unfortunately datasheets seem non-existent leaving us in the dark!
I noticed they seem to run 100 LEDs in parallel. On lengths over 120mm they run another parallel section in series to make up the remaining length.
If I underpower the filament I can see the individual LEDs and it ruins the effect. They need to be brighter to look more like a solid tungsten filament. But overpowering them is bad.
Most sources recommend limiting the current to 50 or 100mA.
But I did some testing and let one run for 3 days at 200mA - it seemed to be just fine. However the 250 mW resistor was understandably hot since it was burning off the excess 400 mW!
At 5V I recommend using a 22 ohm resistor for any length up to 120mm. However, longer versions need more current, so I recommend two 22 ohm resistors in parallel. This reduces the resistance a