TL783 regulated B+ 250V PSU schematic

[eranrund]

Hello gentlemen,

Below is my attempt at a regulated 250v PSU, for driving two E88CC triodes.
Any comments/suggestions?
All capacitors except 10uF are Aluminum Electrolytic, 10uF are MKP.
Resistors are metal film 5%, 2W.

I tried searching the forum for similar designs but nothing concrete came up.

Thanks

[mach1]

I would lose the large 100uF cap on the output as well as the 470R series feed resistor which raises the nice low output impedance of the TL783.

[jackinnj]

To "regulate" the TL783 needs to see at least 15mA load -- so you need current of this amount to flow from the output to adjust -- Texas Instruments recommends 82R.

Make sure that you use an adequately sized resistor from the adjust pin to ground -- at least 5 watts, preferably 7 watts.

So Output to Adjust 82R, Adjust to Ground 16K/7W.

The series resistor in the output -- omit this.

Read the data sheet from TI.

[Andypairo]

Well the datasheet actually states that the 15mA need to flow from the output, so you (only) have to ensure that the load current is > 15mA in any condition.

Cheers

Andrea

[jackinnj]

Yes but, no but, yes but, no but....

15ma across 82 ohms is 0.018 W.

15ma @250V is 3.75 W.

So, you're just burning energy -- if you're running a Class-A amp and the device is going to cook anyway -- it doesn't matter. If the load is going to vary all over the lot, then the lower value from OUT to ADJ is a better idea.

Anyone who runs a class-A amplifier will probably be hunted down by the next Stateside Administration. I hear that the Green Wing of the Dem party wants them outlawed -- and we'll all be listening to MP3's on Class-D amplifiers anyway.

[Renron]

Originally posted by jackinnj
Yes but, no but, yes but, no but....

15ma across 82 ohms is 0.018 W.

15ma @250V is 3.75 W.

So, you're just burning energy -- if you're running a Class-A amp and the device is going to cook anyway -- it doesn't matter. If the load is going to vary all over the lot, then the lower value from OUT to ADJ is a better idea.

Anyone who runs a class-A amplifier will probably be hunted down by the next Stateside Administration. I hear that the Green Wing of the Dem party wants them outlawed -- and we'll all be listening to MP3's on Class-D amplifiers anyway.

Jackinnj,

ROTFLMAO!

Well said. I'm putting nighttime covers on my tubes...

Ron

[wakibaki]

Originally posted by jackinnj
-- and we'll all be listening to MP3's on Class-D amplifiers anyway.

This is a base slur. Class-D amplifiers yes, but nobody said anything about MP3s, which everybody knows are intrinsically more power hungry than uncompressed.

I know it's your politics, but the whole world's praying we don't get another idiot like the last one. Even us atheists.

w

I'm a republican too, it just means something different when you live in a monarchy.

[Renron]

Originally posted by wakibaki


I know it's your politics, but the whole world's praying we don't get another idiot like the last one.
I'm a republican too, it just means something different when you live in a monarchy.

Your entitled to your opinion....but not here. This is an inappropriate thread / forum for that type of comment. Let's stick to Audio related comments. OK?

Hey, I have my thoughts too, but this 'aint the place.
Personally, I don't like being told what I can or cannot do by my government. No one was called any names or attacked in the posting of this message.

Ron
(and I approve this message)

[jackinnj]

Originally posted by wakibaki


This is a base slur. Class-D amplifiers yes,

As long as you shield the Class-D amplifier in a Faraday Cage...

Getting back to the matter at hand, the TL783 would probably benefit from a MKP from adjust to ground -- this will knock down the noise quite a bit (although it isn't helpful for transient response, as TI points out.)

Just remember, JOBs is a 3-letter word, spread it around.

[wa2ise]

Originally posted by various people here


I would lose the large 100uF cap on the output

-----

we don't get another idiot like the last one.


I have my thoughts too, but this 'aint the place.

I could have done better, and I have no political skills whatsoever...

Back to audio: I'd be worried if that regulator could take it if the output should get shorted to ground, or takes enough of a nosedive to overvoltage the regulator's ratings. The cap will look like a short for some brief period of time, long enough to kill the regulator. Instant chip death, and probably will blow shorted, feeding unregulated full B+ to the load. Doesn't take much to kill semiconductors, transients tubes laugh at will take out solid state.