Need math help on resistive power supply...

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 ???

Fixed!!

Need math help on resistive power supply...

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.

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

Resistive part is now done: