Eric, thanks for the LEDs.
TvTech is right about "discharge". I think Colin needs a different word, like 'reset' or '???'. The Zener is used as a diode to conduct the negative half of the current while the positive half goes through the LEDs. The positive and negative currents must balance (equal).
Why don't you tell what you really feel? Tell us why.
Hi Ron
Here is why. I have in the last two years pushed the "envelope" as such with transformerless mains power supplies... There is a design I promised to show here when I initially joined here a while back. Design is rock solid and good to go.
Thing is, my original circuit just keeps getting better and better and has now become a serious shock hazard...
1. Original design was to power Eight white 20Ma 20 degree 15000 mcd LED's directly from 220VAC Mains, complete with backup battery and charger all smaller (or the same size) as a normal glass light bulb (like you use in your house). The circuitry and limited space needed double sided PCB's professionally made and extremely well designed.
PCB's and all LED's have passed all tests with flying colours. For more than Two years. Static discharge on the "head", where the LED's are mounted is a area I must fix...but easily done.
The Mains X2 cap does all the work in my design. It's a 2.2uf 275VAC rated cap. Maximum current (short circuit conditions) is 125 mA. Enough to kill if you are really clueless. No bare feet touching ground here...if you are a TV tech like me, you get a tingle and realize you must be VERY careful..
2. To the new level. A guy I know goes over to China. He brings back samples of COB. That means Chips On Board. Amazing stuff. Bright as all hell. Needs more current than my original design can supply. What do I do as a designer and developer of this baby?.....I push it to the limits..
First of all a test. I want to see how reliable X2 caps really are. These caps are able to survive almost anything. In my years as a tvtech and thousands of TV's, I have probably only seen about 3 or so fail.
One memorable Sunday morning...my friend and I decide to test this reliabilty and my little indestructible light. We ran it on 395VAC for about a Minute...like sixty seconds. No explosions no drama. The light works still..
Try that with a SMPS. You will first of all have a very hot (and possibly exploded) Main smoothing Cap. And dead SMPS.
3. So, with all this in mind, I decide to really push the envelope with transformerless power supplies:
LOL...this is REALLY LETHAL unless you know what you are doing...
The best my ORIGINAL circuit can handle is 5X 2.2MF 275VAC caps in parallel. Which equals around 600 Milliamps into a short circuit. Dont try this ever.
Unless you are able to deal with it safely. And know what you are doing.
Safe regards,
tvtech