A
Arfa Daily
Guest
"dave" <ricketzz@earthlink.net> wrote in message
news:sfadnZq5gaMnD7XPnZ2dnUVZ_rednZ2d@earthlink.com...
Which is exactly what I said. If running them on AC, they are fine as long
as the series resistor is of sufficient value to limit the forward current,
and the reverse voltage on the opposite half cycle does not exceed the
rather low PIV that LEDs tend to have. That aspect can be mitigated by
having a conventional diode in inverse parallel, but this will result in a
flicker at half the supply frequency that Phil can't see, but some of us
can, or by putting another LED in inverse parallel, which will conduct on
the opposite half cycle producing light, and clamping the reverse voltage
across the first diode to the value of the forward voltage of the second
diode, different, of course for different colours. The inverse is also true
that the first diode will clamp the reverse voltage across the second diode
on the opposite half cycle.
Arfa
news:sfadnZq5gaMnD7XPnZ2dnUVZ_rednZ2d@earthlink.com...
On 09/04/2013 06:14 PM, Arfa Daily wrote:
Although of course, care needs to be taken that the lamps are actually
being fed with DC.
LEDs run fine on AC, as long as the voltage and current are within limits.
Which is exactly what I said. If running them on AC, they are fine as long
as the series resistor is of sufficient value to limit the forward current,
and the reverse voltage on the opposite half cycle does not exceed the
rather low PIV that LEDs tend to have. That aspect can be mitigated by
having a conventional diode in inverse parallel, but this will result in a
flicker at half the supply frequency that Phil can't see, but some of us
can, or by putting another LED in inverse parallel, which will conduct on
the opposite half cycle producing light, and clamping the reverse voltage
across the first diode to the value of the forward voltage of the second
diode, different, of course for different colours. The inverse is also true
that the first diode will clamp the reverse voltage across the second diode
on the opposite half cycle.
Arfa