I am using a 5 Watt PCB mount AC/DC power module with universal input(85-264 V) and output as 12 V. The cost of the module is very high so thought if we could replace the module with a PCB mount transformer which will convert 230 VAC to 12 VAC and then a rectifier with a linear regulator can be used for 12 VDC output. I cannot decide the VA rating of the PCB mount transformer size. I did some search and found that I need power factor for getting VA rating. How can I get power factor? I have space constraint on my PCB so I cannot go for a very big transformer. Please suggest a solution. I am new to electronics so please excuse me for my ignorance.
I did some search and found that I need power factor for getting VA rating.
No, power factor has no influence on the VA rating. If your DC load is less than 5 watts then you can use a transformer that is capable of providing more than 5 VA usually. I would be tempted to go for something that is more like 10 VA but this may be too big for your needs.