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
