Need math help on resistive power supply...

[AtomSoft]

Ok im getting made here but at the equations used ...

Look at this equation... from ... AN954

This equation should be:

SQUARE ROOT OF (2*VRMS-VZ) / 2*R1

Correct?

If so then :

SQUARE ROOT OF (2*120-5) / 2*1800

then

SQUARE ROOT OF (235) / 3600

then

15.32970971675589 / 3600

then

why is my outcome 0.0042582526990989

4.25mA and not 45.8mA ???

 

[AtomSoft]

Fixed!!

Need math help on resistive power supply...

 

[MrAl]

Hello there,

So you want 5v output at 45ma right, or a different current output?

If you use a 1.8k resistor you'll have to make it a 12 watter or better. It's going to get rather hot too.
You also need a diode or a bridge rectifier for DC output.

 

[AtomSoft]

yeah.. i got that... Take a look at this.. Im making a calculator for this kind of stuff now to help others..

Next ill add the calc for the Power and also the Capacitance version

 

[AtomSoft]

Resistive part is now done: