Simple resistive dropper for LED filament lamp.

Описание: This is the test of a simple power supply for the LED filament lamp.
It uses full wave rectification and proper smoothing for flicker-free operation.
It's basically a 100 ohm resistor to limit inrush current to a full wave rectifier charging a 4.7uF 400V capacitor. The resultant DC voltage is then applied to the LED lamp via current limiting resistors. I used two quarter watt 10K resistors to get a current of 4mA, which is about a third of the normal current for this "4W" lamp, but kept the dissipation well within the limits of the resistors. (just 160mW for 250mW resistors). I could have increased the current by reducing the value of the resistors, but I prefer my electronics to run cool.
Note that I added some flexible leads to the glass LED globe and resined them into the base to avoid accidentally breaking off the existing wires coming through the glass seal.
This was really just an experiment to see how simple I could make a power supply for the lamp using standard robust components. It also suggested that the original power supply for the lamp was probably dissipating near to 1W from quite a small linear regulator chip.
Here's the data:-
Smoothed DC voltage 336v
Lamp voltage 256v
Voltage across resistors 80V
Lamp current with 2 x 10K resistors 4mA
Resistor dissipation 160mW per resistor