SMPS - Switching Mode Power Supplies - Any example ?

[keithdoxey]

EEEEKKKK!!!!!!

OK, so it does say that the circuit is NON ISOLATED and DANGEROUS VOLTAGES EXIST EVERYWHERE but I would suggest that by having the dropper resistor in the neutral leg rather than the HOT leg, it is making it more dangerous than it need be.

If the resistor fails then the circuit stops working but EVERYTHING WILL STILL BE LIVE whereas if the resistor was in the live leg and failed then it would still stop working but the majority of the circuit would only be connected to neutral. Still wouldnt want to touch any part of it though!

Obviously using a 2 pin mains connector would mean that there is no guarantee of polarity anyway so the above point would be irrelevant.

[mister_e]

i agree, it's ALWAYS dangerous if not properly insulated from the user.

You could be surprise to look at some TV schematic... no coincidence why the user button are as this far of the front plate and have those plastic shaft in between.

If you know what you do, if you install enough protection, if you screen the user from any potential risk, life is good.

You don't want to reverse engineer most programmable thermostat, cofee maker, etc etc...

Advanced components industries, do some nice small transformer.
http://www.advancedcomponents.com/go...FQy8QAodBl8-OA