switching FETs or relays

[Jamie]

Jamie wrote:




*TTL* does not run from a negative rail.

Graham

Talk about running, you should start!

I just love how you take what you need so that
you can engineer it to your design. I never said
TTL worked below 0 volts, did I? You worthless
piece of garbage!

Since you're from an english society that every
one is suppose to look up to as an example, I just
hope you are not! A classic example. If so, it
sure spoils my view of England.

And to think, My grandfather was 100% english (Holmes),
and he was a perfect example of a real Brit, what's your excuse?

 

[Eeyore]

I never said TTL worked below 0 volts, did I?

So where does your alleged -2.5V output come from ?

Graham

 

[Jamie]

Jamie wrote:




So where does your alleged -2.5V output come from ?

Graham

You fabricated it. or you simply can't read.

 

[Eeyore]

You fabricated it. or you simply can't read.

LIAR

 

[[email protected]]

You fabricated it. or you simply can't read.

What Jamie wrote was

#4
Last time I went to school for this (years ago, experienced
followed) logic was +2.5 and up for ON State, -2.5 and down for
Off state. Anything between that was undefined. in the case of
TTL , +2.5V and up was on, anything below was off.

Maybe things have changed ?

So, technically speaking, Jamie never explicitly claimed that TTL ran
from a negative rail.

It has been claimed that the -2.5V is a typo for +2.5V, but not by
Jamie, who would thus seem to be implicitly claiming that TTL needs a
negative rail, but it may be a little unkind to take his posts too
seriously.

Anybody who thinks that 2.5V is any kind of threshold for TTL isn't in
close touch with reality.

 

[JimW52]

HCT input levels are specified for compatibility with TTL, assuming a
5V supply rail - anything from 0V to 0.8V is guaranteed to be
recognised as a low, anything between 1.4V and 5V is guaranteed to be
recognised as a high.

Can no one get this right? VIH is defined as >= 2.0V.

Jim

 

[Genome]

Great, this does make sense. I Appreciate that Genome. Thank you

 

[[email protected]]

Can no one get this right? VIH is defined as >= 2.0V.

Oops. Sorry. that should have between "between 2.0V and 5V".

I blame jetlag.

 

[Fred Bloggs]

Oops. Sorry. that should have between "between 2.0V and 5V".

I blame jetlag.

That's not right, Vih,min is 2.2V and Vil,max=0.8V, Voh,min=2.4V and
Vol,max=0.4V at fanout of 10 UL.

 

[Spehro Pefhany]

That's not right, Vih,min is 2.2V and Vil,max=0.8V, Voh,min=2.4V and
Vol,max=0.4V at fanout of 10 UL.

?? Vih is 2.0 (min) for 7400 74LS00 and 74S00, no? So guaranteed
noise immunity is 400mV high or low.


Best regards,
Spehro Pefhany

 

[Fred Bloggs]

?? Vih is 2.0 (min) for 7400 74LS00 and 74S00, no? So guaranteed
noise immunity is 400mV high or low.


Best regards,
Spehro Pefhany

That's right.

 

[JosephKK]

[email protected] [email protected] posted to
sci.electronics.design:

No, nothing has changed. TTL was always driven between a +5V rail
and a 0V rail. A low output was always between 0V and 0.4V, and a
high output between 2.4V and 5V.

Check any data sheet.

focus.ti.com/lit/ds/symlink/sn7400.pdf

I can't imagine who might have taught you +/-2.5V - do let us know
the name of the school that you think taught you that. You may be
able to sue them for fraud, but if you are sufficiently out of touch
with reality not to have learned better, I can't hold out much
hope..

The levels are actually credible, for pre-TTL/DTL/RTL circuitry. I
have actually worked on computers that used very different logic
levels; some nearly like these. Just the same those levels are
something like i would expect of a vacuum tube computer.

 

[MooseFET]

[email protected] [email protected] posted to
sci.electronics.design:





The levels are actually credible, for pre-TTL/DTL/RTL circuitry. I
have actually worked on computers that used very different logic
levels; some nearly like these. Just the same those levels are
something like i would expect of a vacuum tube computer.

In tube based stuff I'd expect a 25V swing.

 

[Jamie]

Jamie wrote:




I expect it has more intelligence than YOU !

It would be difficult for it not to have a more pleasant character too. I
suggest you leant how to temper your arrogant IGNORANCE from your dog.

Graham

If I learned to be like my dog, we wouldn't be having this
discussion. Instead, I'd be out looking for you so I could rip off a few
limbs.
(German Shepherd+Rottweiler) Nice combination. Big jaw full of teeth.!

She knows the difference between people with respectable integrity
and those that have faults hopes of fame and glory, trying to white
wash the general community.

 

[Eeyore]

If I learned to be like my dog, we wouldn't be having this
discussion. Instead, I'd be out looking for you so I could rip off a few
limbs.

Typical American response. Your ignorance has been roundly and rightly ridiculed
so you respond with aggression.

Graham

 

[Jamie]

Jamie wrote:




Typical American response. Your ignorance has been roundly and rightly ridiculed
so you respond with aggression.

Graham

Well Mr Ham.

I take it you don't like how my dog thinks either?

Shame on you!
Just when I thought you were reforming.

Beware of strangers baring gifts.

Now go have some Tea and Crumpets
you grumpy old fart.