EL84 Triode PP Design

[sorenj07]

Damn, I left my copy in my dorm... is it copyright infringement to ask if there are any scans of the book floating around? i DO own it...

also, am I right in guessing that the plate load resistors don't need to be offset when using a CCS as opposed to a tail resistor?

 

[Salas]

Audio,

Perhaps neither Stuart or I have explained completely (Stu, if I have you completely wrong, scold at will). The problem here is a regulator (voltage or current) that will reliably operate at a drop of 2v or less. Under conditions of dynamic cathode swing, maybe a lot less. What if your tail is going in and out of regulation with signal?

With the right CCS chip, maybe you could even take a bridge and supply off the heater winding (the heaters, with their several amps draw would probably never even notice), and get your chip over the problem; but the bias supply looks like the best bet to me, maybe because I'm planning to do the exact same thing.

To me, trying to regulate current over a volt or two drop looks pretty shaky.

Aloha,

Poinz

You've got my point exactly. The cathode will have 1/2 the input signal across it, which can pop it in and out of regulation. When that happens, those chips tend to scream a bit, not to mention the rather nasty distortion on negative-going peaks.

I ended up to that, even when the off heaters - envelope was ok for the tail swing, bcs the heavy heater cap ripple was creeping through filtering and I could see +/- 100Hz sidebands on 1k signal distortion FFT.

 

[mikey_audiogeek]

LDO current regs

To me, trying to regulate current over a volt or two drop looks pretty shaky.

Mike LaFevre at Magnequest makes some nice 2-pin discrete devices that can do this...

 

[Svein_B]

Damn, I left my copy in my dorm... is it copyright infringement to ask if there are any scans of the book floating around? i DO own it...

If it is just page 134 from the Morgan Jones book you are looking for, you can find it at Google Books (page 134).

SveinB