quick questions
Archiver
Posts: 46,084
If I want to use a transformer to power my board of education how many amps
should it be rated? Can someone recommend where to get one? Ive got one
that is rated 9VDC 1 Amp output but it doesnt seem to work. Oddly enough
when I put my meter on it, it says that the voltage is 12VDC!!! Am I
missing something there?
Also what does Vss and Vdd stand for? I know that they are ground and +5V
but what does they stand for?
Thanks guys
Cy Brown
should it be rated? Can someone recommend where to get one? Ive got one
that is rated 9VDC 1 Amp output but it doesnt seem to work. Oddly enough
when I put my meter on it, it says that the voltage is 12VDC!!! Am I
missing something there?
Also what does Vss and Vdd stand for? I know that they are ground and +5V
but what does they stand for?
Thanks guys
Cy Brown
Comments
plain old transformer) is most likely not regulated, and is rated to put out
9VDC at an actual load of 1 amp, no load the output will be much higher,
hence the 12V reading.
If it is just a transformer and is not rectified and filtered, you must
realize that transformers are commonly labeled with the output voltage RMS,
which is only about 70% of the peak output, that would explain the higher
reading.
I can't remember what Vss and Vdd stand for off the top of my head, I think
there is some history to it. If you ever see a schematic with a part
labeled DS, it is "Daylight Simulator" a.k.a. "light bulb". That is my
favorite acronym on schematics.
--Dan
>From: "Cy Brown" <bushman@t...>
>Reply-To: basicstamps@yahoogroups.com
>To: <basicstamps@yahoogroups.com>
>Subject: [noparse][[/noparse]basicstamps] quick questions
>Date: Fri, 2 Feb 2001 16:04:29 -0600
>
>If I want to use a transformer to power my board of education how many amps
>should it be rated? Can someone recommend where to get one? Ive got one
>that is rated 9VDC 1 Amp output but it doesnt seem to work. Oddly enough
>when I put my meter on it, it says that the voltage is 12VDC!!! Am I
>missing something there?
>
>Also what does Vss and Vdd stand for? I know that they are ground and +5V
>but what does they stand for?
>
>Thanks guys
>
>Cy Brown
>
>
>
>
>
>
>
>
>
_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com
remember correctly... it's been too many years :-)
Something like that anyway...
Regards,
Don
--- In basicstamps@y..., "Cy Brown" <bushman@t...> wrote:
> Also what does Vss and Vdd stand for? I know that they are ground
and +5V
> but what does they stand for?
>
> Thanks guys
>
> Cy Brown
> Vss and Vdd come from CMOS terminology... Source and Drain if I
> remember correctly... it's been too many years :-)
>
> Something like that anyway...
>
> Regards,
> Don
>
> --- In basicstamps@y..., "Cy Brown" <bushman@t...> wrote:
> > Also what does Vss and Vdd stand for? I know that they are ground
> and +5V
> > but what does they stand for?
> >
> > Thanks guys
> >
> > Cy Brown
This subject came up at work the other day.... and talking to the senior
Layout guy,
he himself was not sure, but thought that Vss for source and Vdd for
drain was a
good guess. Actually the source and drain can be interchanged so this
conclusion
would not apply. ...And why not Vd or Vs instead of Vdd and Vss? What
about Vcc?
Beau Schwabe
(Mask Designer)
Network Products Division
National Semiconductor Corporation
500 Pinnacle Court, Suite 525 Mail Stop GA1
Norcross, GA 30071
negative voltage on the IC. Don't know where Vdd came from; could it be "v
drain"? The terms started with the introduction of CMOS.
Ray McArthur
Original Message
From: Beau Schwabe <bschwabe@a...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, February 02, 2001 7:00 PM
Subject: Re: [noparse][[/noparse]basicstamps] Re: quick questions
> drussel2@s... wrote:
>
> > Vss and Vdd come from CMOS terminology... Source and Drain if I
> > remember correctly... it's been too many years :-)
> >
> > Something like that anyway...
> >
> > Regards,
> > Don
> >
> > --- In basicstamps@y..., "Cy Brown" <bushman@t...> wrote:
> > > Also what does Vss and Vdd stand for? I know that they are ground
> > and +5V
> > > but what does they stand for?
> > >
> > > Thanks guys
> > >
> > > Cy Brown
>
> This subject came up at work the other day.... and talking to the senior
> Layout guy,
> he himself was not sure, but thought that Vss for source and Vdd for
> drain was a
> good guess. Actually the source and drain can be interchanged so this
> conclusion
> would not apply. ...And why not Vd or Vs instead of Vdd and Vss? What
> about Vcc?
>
>
> Beau Schwabe
> (Mask Designer)
> Network Products Division
>
> National Semiconductor Corporation
> 500 Pinnacle Court, Suite 525 Mail Stop GA1
> Norcross, GA 30071
>
>
>
>
>
>
>
>
>
>
naming transistor parameters and so Vcc was collector voltage. I'm not sure
why they double it other than to avoid confusion with nodal voltages
(remember nodal analysis) where you have Va, Vb, etc.
I always remember that the S is like a Snake going into the ground.... that
got me through lots of long days staring at MPUs under a microscope at
Motorola visualizing snakes on the ground planes... All the things I'd use
to remember Vdd wouldn't be polite.
Al Williams
AWC
* PAK-I and PAK-IV sale extended one more week:
http://www.al-williams.com/awce
>
Original Message
> From: Ray McArthur [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=maMaKOUdm6TppnVjigi-QPzqJ8Z9F1yrpEsQXaqxfueBjEepkicSh0FpLk8_SVYpVFl-uIFHvYB99g]rjmca@u...[/url
> Sent: Friday, February 02, 2001 7:22 PM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] Re: quick questions
>
>
> I believe Vss is "v substrate", the chip substrate being biased
> to the most
> negative voltage on the IC. Don't know where Vdd came from;
> could it be "v
> drain"? The terms started with the introduction of CMOS.
>
> Ray McArthur
>
>
Original Message
> From: Beau Schwabe <bschwabe@a...>
> To: <basicstamps@yahoogroups.com>
> Sent: Friday, February 02, 2001 7:00 PM
> Subject: Re: [noparse][[/noparse]basicstamps] Re: quick questions
>
>
> > drussel2@s... wrote:
> >
> > > Vss and Vdd come from CMOS terminology... Source and Drain if I
> > > remember correctly... it's been too many years :-)
> > >
> > > Something like that anyway...
> > >
> > > Regards,
> > > Don
> > >
> > > --- In basicstamps@y..., "Cy Brown" <bushman@t...> wrote:
> > > > Also what does Vss and Vdd stand for? I know that they are ground
> > > and +5V
> > > > but what does they stand for?
> > > >
> > > > Thanks guys
> > > >
> > > > Cy Brown
> >
> > This subject came up at work the other day.... and talking to the senior
> > Layout guy,
> > he himself was not sure, but thought that Vss for source and Vdd for
> > drain was a
> > good guess. Actually the source and drain can be interchanged so this
> > conclusion
> > would not apply. ...And why not Vd or Vs instead of Vdd and Vss? What
> > about Vcc?
> >
> >
> > Beau Schwabe
> > (Mask Designer)
> > Network Products Division
> >
> > National Semiconductor Corporation
> > 500 Pinnacle Court, Suite 525 Mail Stop GA1
> > Norcross, GA 30071
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
> > Vss and Vdd come from CMOS terminology... Source and Drain if I
> > remember correctly... it's been too many years :-)
> >
> > Something like that anyway...
> >
> > Regards,
> > Don
> >
> > --- In basicstamps@y..., "Cy Brown" <bushman@t...> wrote:
> > > Also what does Vss and Vdd stand for? I know that they are ground
> > and +5V
> > > but what does they stand for?
> > >
> > > Thanks guys
> > >
> > > Cy Brown
Beau Schwabe wrote:
>This subject came up at work the other day.... and talking to the senior
>Layout guy,
>he himself was not sure, but thought that Vss for source and Vdd for
>drain was a
>good guess. Actually the source and drain can be interchanged so this
>conclusion
>would not apply. ...And why not Vd or Vs instead of Vdd and Vss? What
>about Vcc?
Hi Beau,
It's good to read you on the list. I was wondering if you have your
web site back up somewhere?
The way I heard about Vxx was in relation to biasing and loading a
linear amplifier:
load
;---/\/\----Vcc or Vdd (+) power
|
/ Vc or Vd collector or drain
Vb |/
----|
|\
| Ve or Vs emitter or source
|
'---/\/\---Vee or Vss (-) power
load
The single letters apply to the transistor itself, the double letters
apply to the power supply on the other side of the load or biasing
resistors.
Designations like Vce or Vg, apply to the voltage between the
respective terminals of the transistor, "collector to emitter", "gate
to source".
It is really gets crazy when you deal with complementary devices like
PNP or P-channel MOS, which should really invert the entire picture
above. But in practice that does not happen at least when dealing
with digital logic. The labels are all done with respect to the NPN
or N-channel device. For example, in CMOS, the load for the N-channel
device is a P-channel device (and vice versa):
;
Vdd (+) power
|
| Vs source p-channel
Vb |-'
;-->||
| |-;
| | Vd drain p-channel
INPUT-o |
| o---- OUTPUT
| |
| | Vd drain n-channel
| |-'
`--<||
|-;
| Vs source n-channel
|
'
Vss (-) power
So Vdd is actually tied to the source of the top p-channel MOS-fet.
Just view it as a historical leftover, like "breadboard".
regards,
Tracy Allen
electronically monitored ecosystems
http://www.emesystems.com