23 Aug
2015
23 Aug
'15
4:06 p.m.
On 08/23/2015 07:10 AM, dwight wrote:
I've used the capacitor method to provide most of
the drop in the
past. I don't usually max out the LEDs at 20ma. I find there is
little difference between 10 and 20ma. Yes, the 10 ( or 20ma ) is
current flow through the capacitor. It is necessary to have some
resistor in series as well to suppress line spikes.
Another similar dirty trick back in the day was to run a 6SL7
dual-triode form the line using a 1.0 uF nonpolar capacitor in series
with the line to provide a supply for the 500 ma 6.3 v heater and then
use one of the triode sections as a half-wave rectifier. You thus had
the other triode section for whatever stupid purpose. Of course, this
was horrible abuse of the tube, particularly in the area of
heater-cathode voltage ratings. It probably wouldn't work as well in
220VAC countries, but it worked well enough in the 120VAC ones.
--Chuck