Elimination of transformer .Is It Possible?

[agentnikoli]

Hi friends .I want a 20 volt dc <SAY> directly from AC Mains without using a transformer .Is it possible to acieve wht i want? Plz help .
-Thank u

 

[agentnikoli]

** Note. The DC current is very nominal say about few mili amps <upto 250 mili amps>

Basically the ckt which i wish to work on the set up involves a 555timer and a dc 547 transistor switching a 12 v torch bulb <150 mili amps>
-------------------------------------------------------------------------------------

 

[Nigel Goodwin]

You can simply drop the mains down with a 'ballast resistor', using a constant load to keep the voltage the same - but it's very wasteful in generating loads of heat. Instead of a resistor you can use a 'capacitor ballast', which doesn't generate loads of heat, but does require a suitably rated capacitor - and usually of a perculiar value.

Both methods have been used over the years, the capacitor version is probably best - particularly with such a large drop.

In both cases, everything in the circuit is live to mains, so you need to construct accordingly.

 

[agentnikoli]

Thanks bro . Using a ballas capacitor didnt really strike me .
Thanks a lott

 

[elec_lover]

Here is another discussion were a transformer less design is used:
https://www.electro-tech-online.com/threads/pic-chip.5832/

 

[Styx]

you could just use an autotransformer - basically an inductive voltage divider, then use this "potted" down voltage to go into a rectifier.