MEXICOWANDERER wrote:
Gordon Three, I am having horrid internet connectivity and with the link on the bottom, it displays a schematic for a blinking LED using a 1-watt zener. But I believe the circuit is for British 220 volt power? The neutral resistor power rating remains but at half resistance and the line cap retains the listed uf but the .47uf connector cap uf is doubled, or halved? I have the specs but need to download the circuit and I must get those parts ordered tomorrow or wait three months. Help? This is solely (changing over to a) dealing with a circuit with half the line input voltage. My flash memory failed me. The site has come up blank with a few dozen tries. Sundial ping PONG. Mil gracias.
Sorry for my delayed response...
I'd have to dig out the math behind how selecting the component values, but I wager the capacitor's value isn't super critical, 100-1000nF to (0.1 to 1uF) seems to be the range in play here, the smaller the cap the less current you sneak from the waveform. for 110v north american voltage you can probably get away with 150-200 volt rating on the cap versus the 275+ rating they need over the pond.
Same for the "safety" resistor on the neutral - its just a backup for the capacitor, so it'll burn out if the cap should short somehow.
the zener and electrolytic are a shunt regulator right? trying to keep the voltage sane for the blinker led. their values stay the same.
!! BUT !!
I like DrewE's idea ... let China do the heavy lifting with a 5v USB charger. Since you're ordering parts, and you're no stranger to EBAY:
clicky9 bucks shipped gets you 4x five volt one amp power supplies with universal voltage input, and probably a little more safety factor than a capacitor and resistor give you.
