How can l use caps to stepdown or reduce mains voltage

[kofi Mpengya]

l quite remember when l was a kid l use to see no transformer but only
caps in my oldman's battery charger. It was strong and reliable.Thus
anyone know much about this technology? l will be pleased if he or she
can share this with me Thanks .

 

[Robert Baer]

l quite remember when l was a kid l use to see no transformer but only
caps in my oldman's battery charger. It was strong and reliable.Thus
anyone know much about this technology? l will be pleased if he or she
can share this with me Thanks .

Basically, the capacitor in series with the load aer an AC voltage
divider.
Determine the AC impedance of the load, and then required dropping
impedance of the capacitor, then the capacitance.
Good for resistive or capacitive loads.
Inductive loads cannot be calculated this way, as there is a
"resonance" phenominum that will make voltage drops in excess of the
line voltage.

 

[Craig]

The post above is correct re voltage dividers. It is not just cap as
such (caps can increase voltage sometimes) but the way they are used
too.

Below is a site that explains voltage dividers without to much fuss.

http://www.aikenamps.com/VoltageDividerRule.htm

If this link fails go to http://www.aikenamps.com
tech info section and the article is in the introductory-beginner's
section.

Cheers
Craig Ryder

 

[N. Thornton]

kofi Mpengya wrote:

Basically, the capacitor in series with the load aer an AC voltage
divider.
Determine the AC impedance of the load, and then required dropping
impedance of the capacitor, then the capacitance.
Good for resistive or capacitive loads.
Inductive loads cannot be calculated this way, as there is a
"resonance" phenominum that will make voltage drops in excess of the
line voltage.

Hi

I've used Cs to reduce V on L loads, and it works fine. Inductive
loads are of course RL loads, not pure L. I've used it for reducing
power on various motors, current controlling fl lights, and in light
low cost PSUs. Works great!

For your battery charger all you need do is size your cap to pass the
required current at Vmains - Vbatt. But I really wouldnt do it...
1. your battery and charger terminals will be live
2. the V applied to a flat or full battery will be excessive.
3. So you might die.

Regards, NT

 

[JeffM]

l quite remember when l was a kid l use to see no transformer but only

So you might die.
Robert Baer

Yup. Make out your will first.
In Europe, they have outlawed these.
shorted capacitor==death