When did B+ become Vdd or whatever it is?

Fred Hawkins

I am getting old. Even Wikipedia doesn't remember b+.

ratronic

I was a consumer electronics technician for 20 some years, I remember B+ in more ways than one!!!

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Fix it if ain't broke·

D Rat


Dave Ratcliff· N6YEE

RDL2004

I think it went away when transistors took over from vacuum tubes.

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- Rick

Bergamot

I think I'm more like a C-

Mike Green

I think the A battery was for the filaments and the B battery was for the plate and maybe the screen as well. Does anyone remember what the other two filaments were for? I think one was for accelerating the electrons that got through the grid and the last one was for mopping up secondary emission electrons from the plate.

parts-man73

I agree with Fred, What's wrong with positive and Negative, or simply + and -

VSS and VDD took alot of getting used to.

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Brian

uController.com - home of SpinStudio

Fred Hawkins

I am now officially a geezer: http://www.antiqueradio.org/bsupply.htm

hippy

parts-man73 said...
I agree with Fred, What's wrong with positive and Negative, or simply + and -

But is "+V" with "-V" the same as 0/2*V, or 0/V, or -V/0/+V ?

Negative and positive suggest 'relative to something else' ( an implied zero ), and in a two rail supply that doesn't really make much sense.

Fred Hawkins

hippy said...

parts-man73 said...
I agree with Fred, What's wrong with positive and Negative, or simply + and -

But is "+V" with "-V" the same as 0/2*V, or 0/V, or -V/0/+V ?

Negative and positive suggest 'relative to something else' ( an implied zero ), and in a two rail supply that doesn't really make much sense.

Fine. You tell the boss who put the battery in upside down.

Beanie2k

Mike Green said...
I think the A battery was for the filaments and the B battery was for the plate and maybe the screen as well. Does anyone remember what the other two filaments were for? I think one was for accelerating the electrons that got through the grid and the last one was for mopping up secondary emission electrons from the plate.

OK, I will now demonstrate to the world how old I am.

There were originally 3 batteries in the old battery operated radios (this is going back to the 1920's). The A battery, like you said, powered the filaments. The B battery supplied the plate and screen voltages (B++ and B+ respectively). There also was originally a C battery, which provided the negative bias voltage. However, it was discovered later that this voltage could be created by putting a resistor (optionally paralleled by a bypass condenser) in the cathode circuit, thus eliminating the C battery.

The first amplifying tube was the triode, which worked well at low frequencies, but at higher frequencies the plate-grid capacitance could cause oscillation due to positive feedback. Adding a second grid (the screen) between the control grid and the plate, and applying a voltage slightly below the plate voltage eliminated the capacitive coupling problem, but introduced a new one. When the electrons from the cathode struck the plate, they would knock a few electrons loose. On a triode these would just go back to the plate, but on a tetrode (aka screen grid tube) they would get attracted to the screen grid instead, a process called "secondary emission". The cure for this? Why add another grid of course, and call the new tube a pentode. This third grid, called the suppressor, went between the screen grid and the plate, and was usually (but not always) tied to the cathode. It's job was basically to chase the electrons back to the plate.

Well, this is probably way more than anyone wanted to know. But if folks are interested I would be happy to dicuss more of this old stuff.

Duffer

While we're on the subject (sort of). Can sombody explain the difference between Vdd and Vcc. I know what they are, but the names seem to be used interchangeably. IS there a difference/distinction between the two?

Good read, Beanie2k! Yup, I remember using the old self-service "Tube Testers" at tha local electronics shop. see below

BTW - If you're looking for these, searching for "tube tester" won't work. You have to search for "VINTAGE Tube Tester"

deSilva

Vc means "Voltage at the Collector", Vcc thus "Voltage at the Collectors"; when FETs came in use, this was the voltage at the Drain(s) of course

Notice that for PNP transistors Vcc was negative!!

Bergamot

Duffer said...
While we're on the subject (sort of). Can sombody explain the difference between Vdd and Vcc. I know what they are, but the names seem to be used interchangeably. IS there a difference/distinction between the two?

Good read, Beanie2k! Yup, I remember using the old self-service "Tube Testers" at tha local electronics shop. see below

BTW - If you're looking for these, searching for "tube tester" won't work. You have to search for "VINTAGE Tube Tester"

That thing looks borderline steampunk.

pwillard

I cut my teeth in TTL chips so I still use Vcc in my head and have a hard time enjoying Vdd as a result.

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There's nothing like a new idea and a warm soldering iron.

Post Edited (pwillard) : 8/21/2007 5:50:50 PM GMT