Substitute for transformer

[mufthas]

substitute of transformer

How to convert 230VAC to 50VAC without using a transformer or resistor network.

 

[DrBob13]

transformator subtitute

Hello mufthas,
If this is a real question for a high school or college problem you could do it using a capacitive divider network, 2 capacitors are used like a resistive divider network. Calculate the reactances of the capacitors required as if you are going to do it using two resistors then calculate the reactance values of the two capacitors required using the standard reactance formula. Do not expect to get much usable power out of the stepped-down connection between the two capacitors though.

I presume this is for a college question that bears no real relation to real world electronics, I would not recommend doing this for a practical power supply project, you could get many serious problems. Capacitive dividers are sometimes used successfully in radio-frequency matching circuits and in other low power signal circuits but do not even think about using them as a transformer substitute in a PSU or even as a source of 50/60 Hz for a signal timing source when it is connected directly to the un-isolated mains input.
Bob.

 

[eem2am]

one way you could do it is to use first a smps converter to get the voltage to 50VDC.

...then you switch this with an inverter using sinusoidal PWM...and then you filter the output to get your 50 VAC

......OR IS IT THAT YOU HAVE TO GET IT TO 25vdc AT FIRST....I NEED TO MAKE SOME DRAwings etc (apologise for capitals)

Anyway, you see what i mean.............

1. rectify the AC.
2. Either smooth it with a cap or use a power factor corrector to give smoothish DC....
3. Then use an smps to convert the smoothish DC to 50VDC.
4. Then throw the 50VDC into and inverter and use that special sinusoidal PWM.
5.Then filter out the high frequecncy to leave you with 50VAC at 50Hz

the sinusoidal PWM........you may get some IC for to do it.....it make pulse width proportional to referecne 50hz sine amplitude

you might even be able to get a module which does a lot of this for you