The plain LED light bulbs on the market...

Thread Starter


Joined Nov 29, 2005
Good day.
Plain LED light bulbs we find at common vendors have the AC to DC conversion 'driver' inside to supply the emitters.
Is there a standard, or customary, or typical DC operating voltage in them or everyone manufactures what they want ? Perhaps different DC voltages are related to the luminosity levels of each bulb 'power' ?

In other words, can the LED bulbs be canibalized and their bare emitting boards fed by pure DC only (as a 12VDC car battery) or there is need to know which voltage each gut works ? Or they go by current ?
If the driver chips work on current regulation; what is the range of DC voltage they accept ?


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Jon Chandler

Joined Jun 12, 2008
Once again, I recommend watching Big Clive on YouTube to learn all manner of things about LED bulbs. He has dissected and reverse-engineered many.

The state-of-the-art is a series string of LEDs with the total Vf approximating line voltage and a dedicated linear current regulator driver chip. A resistor sets the current, and the chip can throttle the current based on temperature.

Incoming power is bridge-rectified, usually with a low-value smoothing cap.

Note that each square LED on the circuit board usually contains many series LED elements, so their Vf is many times the ~3 volts you might expect.