C
Clive Mitchell
- Jan 1, 1970
- 0
Just got a cheap 12V MR16 with 18 red LEDs.
Popped it open for a look inside. There are two PCB's. One with the
LEDs wired as three circuits of 6 LEDs, and the power PCB which simply
has four diodes in a bridge with a 47uF 25V capacitor for smoothing and
a single 39 ohm resistor to limit current to the LED array. Going by
the voltage across the resistor, the expected current of 60mA isn't
achieved until the DC voltage is 15V, so I guess the unit is optimised
for use on traditional wire wound 12VAC transformers.
Interestingly the wires from the base have been soldered to the bi-pins
sticking out of a standard quartz lamp base which has then been cemented
in as normal. I guess it was easier to use existing manufacturing
technology.
Popped it open for a look inside. There are two PCB's. One with the
LEDs wired as three circuits of 6 LEDs, and the power PCB which simply
has four diodes in a bridge with a 47uF 25V capacitor for smoothing and
a single 39 ohm resistor to limit current to the LED array. Going by
the voltage across the resistor, the expected current of 60mA isn't
achieved until the DC voltage is 15V, so I guess the unit is optimised
for use on traditional wire wound 12VAC transformers.
Interestingly the wires from the base have been soldered to the bi-pins
sticking out of a standard quartz lamp base which has then been cemented
in as normal. I guess it was easier to use existing manufacturing
technology.
