how to get 14-24vdc from 12vac

[bent]

hello,

i need to get between 14 to 24 vdc from a 12vac... with a load of 0.5 to 1 amp

i try a diode bridge with a 1000uf cap, but voltage is dropping under load....

any help would be VERY appreciated !!!!!!

bent

[frequencycentral]

Google "%^&*croft walton"

Edit: Oh, the forum is set to censor the word '%^&*' wherever it appears. So I'll spell it out: c o c k c r o f t w a l t o n

[CynicalMan]

If you use schottky diodes, you might be able to get around 14V. But you'll probably need a voltage doubler:


Edit: Rick beat me to it.   The image is an example of a cσckroft walton doubler.
Edit 2: Never mind, that's a Delon multiplier. This is a cσckroft walton doubler:



Confused yet?

[ORK]

Or google: "Villard" or: "Delon" or: "Greinacher"

[bent]

thank's everyone
just try:
                                 1n4001
ac ------ cap + ---------- diode  ---------   +
            220uf     I                       I +
                        diode 1n4001    cap  220uf
                          I                       I
ac ------------------------------------------   -

but i get 39 vdc....to much....

bent

[Hides-His-Eyes]

You're going to use a regulator though, right?

Still, no need for unnecessary strain on the thing. SURE it's 12VAC?

[bent]

no regulator, cause it's going to feed a futurlec +/- 12 vdc board....

yes it's a 12vac ....triad wau12-1000

[bent]

thank's everyone
just try:
                                  1n4001
ac ------ cap + ---------- diode  ---------   +
             220uf     I                       I +
                         diode 1n4001    cap  220uf
                           I                       I
ac ------------------------------------------   -

but i get 39 vdc....to much....

bent

try it with a regulator 7815 and 7824 , but the miniboard doesn't support it ?
dont know why....!

[PRR]

> triad wau12-1000

Secondary Rating: 12VAC ± 5%, 1000mA AC

> i need to get between 14 to 24 vdc from a 12vac... with a load of 0.5 to 1 amp

Won't work well. 12V AC will rectify-cap to about 16V DC, but a 1 Amp DC load reflect back to the AC winding as about 1.8 Amps. Thransformer will run hot and will sag.

> voltage is dropping under load....

Sure would be more useful to SAY what voltage and current you observed, than to ask for an interpretation from Triad's spec-sheet.

wau12-1000 claims 18% regulation with AC load. Sag will be much worse with DC rectifier. I would expect 30%-40% at the maximum 0.55 Amps DC it can handle. Probably 10V-11V at 0.55 Amps.

Do you actually need 0.5A-1A? That's a lot of current. What are you making?

> it's going to feed a futurlec +/- 12 vdc board....

Plus-and-minus 12V is not 12V, it is 24V.



Wire like this. Call the junction of C1 C2 "ground", and take the 3 wires to your load. In this connection you can get maybe 0.2 Amps at +/- 10V to 12V DC. If C1 C2 are say 3,300uFd 16V, this UN-regulated supply may be OK for many circuits.