power supply question

[odysseybmx414]

i have a 200va transformer with 20v secondaries i was wanted to know about how many dc volts would this produce? the transformer is rated at 3 amps. And, would this be able to supply a single lm4780 amp?

 

[vmac011]

AC x SQR(2)

in your case 20 Vac x 1.41 = 28.2 Vdc

That transformer is fine for 1 4780 chip.

 

[filholder]

Should produce 28 volts dc. And i would think from what i have read that would be enough for one chip amp.

 

[K-amps]

Should produce 28 volts dc. And i would think from what i have read that would be enough for one chip amp.

Actual DC will be 26.7 to 27.2 depending on the forward voltage drop of the rectifiers you use. They need 1-1.5 volts to forward bias.

 

[Leolabs]

It also depends on the value of the filtering cap.

I recently build an amp with experience like this:

Transformer secondary voltage:34V-0V-34V(approax)

Rectification:full wave bridge

DCV with 4700uF:41V(approax)

DCV with 4700uF+470uF:46V(approax)

 

[odysseybmx414]

big help guys thanx

 

[K-amps]

It also depends on the value of the filtering cap.

I recently build an amp with experience like this:

Transformer secondary voltage:34V-0V-34V(approax)

Rectification:full wave bridge

DCV with 4700uF:41V(approax)

DCV with 4700uF+470uF:46V(approax)

Leo... a 12% increase by using a bypass cap seems like a lot....

 

[jacco vermeulen]

It also depends on the value of the filtering cap.
DCV with 4700uF:41V(approax)
DCV with 4700uF+470uF:46V(approax)

Can i have some of those caps ?

 

[Leolabs]

Strange hah???That's what came out,more capacitance more voltage.No idea what cause this.

 

[K-amps]

Strange hah???That's what came out,more capacitance more voltage.No idea what cause this.

Not just strange... this is bordering funky. Is the experiment repeatable , with different values? I mean I never got a 10-12% increase by doubling my caps let alone slightly increasing them. Granted for very low levels of capacitance, you will get some gain of rails especially under load, but this is too good..... to be real.

 

[jcayer]

i have a 200va transformer with 20v secondaries i was wanted to know about how many dc volts would this produce? the transformer is rated at 3 amps. And, would this be able to supply a single lm4780 amp?

Are you shure about the 3 amps (or the 200va)??

 

[Upupa Epops]

4700 M have " lost " capacitance, that's all.

 

[K-amps]

Pavel... not sure if the comment was in jest, if not please explain.