Smoothing Capacitor Capacitance calculator

[us1070]

Hello

some basic questions about (smoothing caps/filter caps)

1. What is the required smoothing rail Capacitance for a 1k watt draw from a transformer at +-110dc rails?
2. Does using higher voltage require less smoothing capacitor Capacitance ?

Mains: 225vac at 50hz
Single bridge rectifier (4 diodes)
Toroidal transformers v80-0-80v
For ripple 5v at load 8ohms pure resistive

 

[jan.didden]

Depends on the ripple you are willing to accept.
At 50Hz mains, double phase rectification gives 100Hz ripple.

Basically delta-V (ripple) * C = delta-I * t where t = 10ms.
Delta-I should be close to constant at your voltage and power draw (100V @ 1kW = 10A).

Reworked: C = (10A * 10^-2)/V-ripple

Everything in F, A, V, Sec.

Example: for 1V ripple, you need 0.1F = 100,000uF.

Jan

 

[Aucosticraft]

Simple simulation tool

After you get the value of Cf ( filter) I would recommend you to go for simple simulation. It works great if you can create a complex load and check the ripples/noise.

I usually use LTspice.

 

[Conrad Hoffman]

Don't forget to check the ripple current against the cap specs if you want long cap life.

 

[DF96]

mains : 225vac at 50hz

As the mains voltage is irrelevant, please assure us that this PSU will be using a proper isolation transformer. A 1kW PSU should not be built by someone who cannot do even the basic design work himself; it will be too dangerous for him and his family.

 

[Pafi]

05V

? What could that mean? 0.5V? Or 5V?

And what kind of load is it? I guess not pure resistive...

Without knowing the type of the load quite pointless to calculate anything. Trust me, there are big differences!

 

[Pafi]

I made a calculator for amplifiers, ClassAB, D, bridged and single ended, but my homepage where I uploaded is not exist anymore...

 

[sreten]

Hi,

For that sort of power supply your going to need a soft start circuit.

rgds, sreten.

 

[AndrewT]

............... using a proper isolation transformer. A 1kW PSU should not be built by someone who cannot do even the basic design work himself; it will be too dangerous for him and his family.

I agree.

If one does not know this already, then one should not be attempting to cobble this together. It could prove fatal to the Builder and/or any user/operator.