24Vdc Power supply

--- That's true, but you can't achieve that by using the same transformer in a series or parallel configuration because of the effect of the load resistance.

Consider:

E1 | R1 | R2 | GND

Where E1 is the open-circuit output voltage of the transformer, R1 is the resistance of the secondary, and R2 is the load resistance

Let's set conditions up such that the open-circuit voltage is 10 volts, RMS, the secondary resistance (both windings in parallel) is

In that case, the current out of the transformer would be:

E1 10V I = --------- = ----- = 0.909 amperes R1 + R2 11R

and the power dissipated in both secondaries would be:

P = I²R = 0.826 * 1R = 0.826 watt

or, 0.413 watt per secondary.

Now, if we connect the secondaries in series and use each one of them half the time, we wind up with this for each secondary:

so we now have a current in the "hot" winding of:

and a dissipation in the winding of:

Note that 0.694 watts is _not_ twice 0.413 watts. :-(

---

--- Apparently, it is...

---

--- Could be, but at least I can see through yours! ;)

-- John Fields Professional Circuit Designer

"John Fields"

Wot a tedious wanker is this Septic Tank prick from Austin Texas.

" He's a Long Tall Texan ... and he thinks lot of crap ....

He's a Texan and he's full of Crap ..... " .

....... Phil

"John Fields"

Wot a tedious f****ng LYING TURD is this ASD F***ed Septic Tank *Cunt* from Austin, Texas.

" He's a Long Tall Texan ... and he thinks a lot of crap ....

He's a Texan and he's soooo full of Crap ...

Oh Roy, oh Roy - is that your horse ? "

....... Phil

"John Fields"

Wot a tedious f****ng LYING TURD is this ASD F***ed Septic Tank *Cunt* from Austin, Texas.

" He's a Long Tall Texan ... and he thinks a lot of crap ....

He's a Texan and he's soooo full of Crap ...

Oh Roy, oh Roy - is that your horse's arse ? "

....... Phil