Triac Based 220V-110V Converter

Thread Starter


Joined Jan 3, 2008
I have a 220V to 110V wall adapter that uses a small circuit with the main component, a triac. The triac is mounted to a big aluminum heat sink. As I know, these type on converters use face shifting to convert AC voltage, and they shouldn't be used except with resistive loads, such as heating appliances like coffee machine (the adapter I have is for coffee machine and it's written on it something around 50W and up to 1600W...)

I'm wondering if this type of converters work fine on a modified sine wave 220V inverter. I don't know much about thyristors theory.. What do you think?


Thread Starter


Joined Jan 3, 2008
I want to know if it's ok to use these triac converters plugged into 220V modified sine wave source.


Joined Dec 26, 2010
This may refer to a device similar to a TRIAC lamp dimmer, used to operate resistive 120V appliances from a higher voltage AC supply.

Frankly this sounds rather hazardous even when working from a standard 230V AC supply. The waveform is going to be ugly, and if anything goes wrong with the phase control there is liable to be a nasty accident.

I wouldn't really fancy running this sort of thing from an inverter, even if it is supposed to be "sinewave". How good the waveform would remain when loaded by this non-linear contraption would remain to be seen. Possibly the inverter would be also upset by this load, full of harmonic current and with a dodgy power factor.

I may of course be quite wrong, having never used such a thing, but it just doesn't sound like a good idea.


Joined Feb 19, 2009
Have you tried a step down transformer? If so and it gets warm quickly under a light load (due to core saturation), a Triac control wouldn't work, either (you'd get a square wave output from it, which resistive loads like heating elements can handle, but not much else).