Driver to drive?

[Randy McLaughlin]

"John Fields" <jfields@austininstruments.com> wrote in message
news:nn3tu0hv7gkr1amr4s48j4b4d9hqmvge6d@4ax.com...

On Tue, 18 Jan 2005 21:37:41 -0600, "Rhyanon" <pissoff@uberbitch.com
wrote:

WAHAHAHA!! Two replies? For a _correction_ nonetheless? Priceless! You are
a
true weeny!

---
If something's worth doing. it's worth doing well, but I don't suppose
you'd know anything about that...

BTW, there's another error in meter in there; think you might be able
to find it? Probably not, 'meter' to you would be something your Mom
keeps by her bed.

--
John Fields

Please don't cross post.

Randy

 

[Nicholas O. Lindan]

"John Larkin" <jjSNIPlarkin@highTHISlandPLEASEtechnology.XXX> wrote

The ultimate dating service would only need blood samples.

And what a Brave New World it will be.

* * *

I see they just reissued a 'lit crit' edition of the book;
I read it again a few years ago and Huxley was indeed
remarkably prescient.

We may not get the OP a job, but we may get him a hot date as
a consolation prize.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/

 

[Rich Grise]

On Mon, 17 Jan 2005 16:22:23 -0600, John Fields wrote:

On Mon, 17 Jan 2005 15:51:24 -0600, John Fields
jfields@austininstruments.com> wrote:


Ooops... Bad rhyme:

And so that family survives,
a drunk, a whore, four ruined lives,
but Rhyanon's the happiest of lads,
he's got a brother and two Dads!


---
Somewhat better:

And so that family survives,
a drunk, a whore, four ruined lives,
but R's the happiest of lads,
he's got a brother and two Dads!

No, the rhyme's fine - the prob. is with the scansion. You might have to
look that word up - I'm not sure if I've invented it or not.

John Fields, he done wrote us a poem.
The newsgroups, about he does roam.
But when he gets smart,
Not just a brain fart,
I think we should all just go home.

Thanks,
Rich

 

[Randy McLaughlin]

"Rich Grise" <richgrise@example.net> wrote in message
newsan.2005.01.19.17.23.38.641939@example.net...

On Mon, 17 Jan 2005 16:22:23 -0600, John Fields wrote:

On Mon, 17 Jan 2005 15:51:24 -0600, John Fields
jfields@austininstruments.com> wrote:


Ooops... Bad rhyme:

And so that family survives,
a drunk, a whore, four ruined lives,
but Rhyanon's the happiest of lads,
he's got a brother and two Dads!


---
Somewhat better:

And so that family survives,
a drunk, a whore, four ruined lives,
but R's the happiest of lads,
he's got a brother and two Dads!

No, the rhyme's fine - the prob. is with the scansion. You might have to
look that word up - I'm not sure if I've invented it or not.

John Fields, he done wrote us a poem.
The newsgroups, about he does roam.
But when he gets smart,
Not just a brain fart,
I think we should all just go home.

Thanks,
Rich

Please stop cross posting.

Randy

 

[Spehro Pefhany]

On Wed, 19 Jan 2005 07:58:52 -0800, the renowned John Larkin
<jjSNIPlarkin@highTHISlandPLEASEtechnology.XXX> wrote:

On Wed, 19 Jan 2005 14:58:54 GMT, "Nicholas O. Lindan" <see@sig.com
wrote:

Interestingly, dating services don't work very well. If two peoples'
objective profiles are matched - height, weight, careers, interests,
all that usual stuff - it doesn't at all indicate that anything will
click when they meet. It's far more effective to let them just sniff
one anothers' used t-shirts; HLA antigen matches (or, actually,
mismatches) are what makes for romance.

Hot Damn! I'm going into business: "Dating Service and Underwear Exchange".


The ultimate dating service would only need blood samples.

John

That would only delay the influence of the male engineer's most
effective form of birth control.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Mark Jones]

Is Lady Chatterly really a bot?

 

[John Fields]

On Wed, 19 Jan 2005 17:18:43 GMT, Rich Grise <richgrise@example.net>
wrote:

On Mon, 17 Jan 2005 16:22:23 -0600, John Fields wrote:

On Mon, 17 Jan 2005 15:51:24 -0600, John Fields
jfields@austininstruments.com> wrote:


Ooops... Bad rhyme:

And so that family survives,
a drunk, a whore, four ruined lives,
but Rhyanon's the happiest of lads,
he's got a brother and two Dads!


---
Somewhat better:

And so that family survives,
a drunk, a whore, four ruined lives,
but R's the happiest of lads,
he's got a brother and two Dads!

No, the rhyme's fine - the prob. is with the scansion. You might have to
look that word up - I'm not sure if I've invented it or not.

---
Excellent word, but according to Webster, "the metrical analysis of
verse".

So, what I did was scansion, and you're right; what I should have
stated was that the meter was bad, not the rhyme. Thanks.
---

John Fields, he done wrote us a poem.
The newsgroups, about he does roam.
But when he gets smart,
Not just a brain fart,
I think we should all just go home.

---
<G>

--
John Fields

 

But I can't help but wonder, what does everybody else do to protect
their
outputs?

Relays (vending machine application). Traces from the contact pins run
directly to the I/O connector, which is used ONLY for this purpose. No
other traces run alongside, amongst or on the other side of the board
from these signals.

 

[John Larkin]

On Wed, 19 Jan 2005 02:44:40 GMT, "Kryten"
<kryten_droid_obfusticator@ntlworld.com> wrote:

Smell is how people know, without being conscious of it. In a sense,
it's not conscious "smell", but people are very aware of antigen
compatibility,

How can you be "very aware" and "not conscious of" something at the same
time.

It's like your vistibular system. You're not really aware of it unless
it quits working, in which case you fall down. We have lots of sensors
and servos that work below the surface.

'Pheromones' are airborne chemical messengers that are not necessarily
perceived as odors. For example, women who are in frequent contact
tend to synchronize their periods, often without being aware of it.
The related chemical messenger has been isolated in sweat.

Google 'pheromone' too.

I've never fancied anyone based on subliminal odours.

That's too bad. Chemical compatibility produces a very warm, chummy
feeling.

John

 

[John Larkin]

On Wed, 19 Jan 2005 12:30:49 -0500, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

On Wed, 19 Jan 2005 07:58:52 -0800, the renowned John Larkin
jjSNIPlarkin@highTHISlandPLEASEtechnology.XXX> wrote:

On Wed, 19 Jan 2005 14:58:54 GMT, "Nicholas O. Lindan" <see@sig.com
wrote:

Interestingly, dating services don't work very well. If two peoples'
objective profiles are matched - height, weight, careers, interests,
all that usual stuff - it doesn't at all indicate that anything will
click when they meet. It's far more effective to let them just sniff
one anothers' used t-shirts; HLA antigen matches (or, actually,
mismatches) are what makes for romance.

Hot Damn! I'm going into business: "Dating Service and Underwear Exchange".


The ultimate dating service would only need blood samples.

John

That would only delay the influence of the male engineer's most
effective form of birth control.

Software?

John

 

[Aunty Kreist]

"Mark Jones" <abuse@127.0.0.1> wrote in message
news:aIKdnS2bZ4OxA3PcRVn-tw@buckeye-express.com...

Is Lady Chatterly really a bot?

Yep.

 

[Aunty Kreist]

"Randy McLaughlin" <randy@nospam.com> wrote in message
news:wzxHd.16747$SK6.9062@bignews3.bellsouth.net...

"Mark Jones" <abuse@127.0.0.1> wrote in message
news:aIKdnS2bZ4OxA3PcRVn-tw@buckeye-express.com...
Is Lady Chatterly really a bot?

Please stop cross posting.

Randy

Follow your own advice.

 

[Andrew]

I might also add that the formula I put up is based on 50% (worst case)
PWM signal!

 

[NSM]

<mroberds@worldnet.att.net> wrote in message
newsypHd.22993$ql2.19021@okepread04...

....
| This is for holding up a cable modem and VoIP box during power outages.
| I know I could just buy a commercial UPS and plug in the wall-warts, but
| it seems wasteful to me to go from 12 V DC to 120 V AC back to 12 V DC.
....

Use the UPS. It's not wasteful and it's way cheaper than do it yourself.

N

 

[Richard Henry]

"Kryten" <kryten_droid_obfusticator@ntlworld.com> wrote in message
news:sQjHd.418$Uf6.94@newsfe5-win.ntli.net...

I've never fancied anyone based on subliminal odours.

Are you sure? google "definition subliminal".

 

[Chris Carlen]

Rich Grise wrote:

On Tue, 18 Jan 2005 17:41:42 -0800, Chris Carlen wrote:

Joerg wrote:

This is usually spec'd in the data sheet. For logic it is often called
"DC output diode current" under abs max ratings. If in doubt, I'd
contact an applications engineer at the manufacturer.

For lines going to the outside world extra Schottkys are often
indispensable, considering the moment of truth when the test lab guy
puts on his cowboy hat and wields that big honking ESD zapper gun.

...

Now the other issue is how to prevent the rails from rising above 5V
when continuous overvoltage is present at an input or output. This is
difficult. A 6.8V TVS across the rails isn't guaranteed to turn on
until about 7.14V.


I'm ass-u-me-ing that "TVS" means "Transient Voltage Suppressor", and from
the spec, it sounds like you're not using a Transzorb:
http://www.vishay.com/diodes/protection-tvs-esd/trans-zorb/

I think they have a much sharper knee than, say, MOVs.

I was refering to a Littlefuse TVS. Vishay Transorb, the 5V variety
such as 5Kp5.0A is similar with 7.0V max turn on. Vishay has double the
reverse leakage it seems as well, 5 times!!! for the 6V flavor. Not
that it matters that much.

But I can't help but wonder, what does everybody else do to protect their
outputs? How fragile are these outputs? Does your box die if you hot-plug
it? The most robust output protection I've ever seen is emitter-follower
buffers with a resistor; I've never seen anyone put diodes to the rails on
an output.

For a CMOS output with or without power, it seems to make sense. An ESD
strike into the relatively resistive output Z of an HC gate, for
instance, is likely to put excessive surge current into the substrate
diodes of the output FETs (ARE there substrate diodes for these FETs???).

Maybe the current would actually be tolerable since they might be
beefier than the input diodes, but who knows? These parameters are
unspecified. Thus, one has to fall back to the continuous current
absolute ratings if you want documented proof that it's protected.

In that case, external diodes are the only way. Try modelling a 15kV
discharge from 150pF, through about 250nH and 300ohms of source
impedance, and straight into a pair of small diodes like 1N4148.

On my HC input protection model, I have a 220ohm R into a pair of 1N4148
diodes, followed be another 100ohms into the actual device pin, which I
model with another pair of 1N4148 diodes and a 4pF cap.

I get 27 peak amps through the first diode, and 150mA peak into the
internal diode. The "gate" voltage reaches about 5.9V, which is within
spec. The internal diode current is still over the maximum allowed
clamp current of 20mA, but it decays to within 20mA within 200ns.

So there's still an element of "hope it's good enough" and many
assumptions about diode characteristics.



Good day!


--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarle@sandia.gov -- NOTE: Remove "BOGUS" from email address to reply.

 

[Chris Carlen]

Joerg wrote:

Hi Chris,

Schottkys drop a lot when large currents are flowing and the diodes are
tiny little versions. What I usually do in situations where things have
to be very tough: A SOT23 (or bigger) diode pair CR1 like usual, to VCC
and GND. A resistor R1 from CR1's center to the outbound connector and
another resistor R2 from CR1's center to the device pin. Even if you'd
take an ordinary silicon diode pair such as the BAV99 for CR1 to save
cost then R2 will prevent the diversion of lots of current into the
device port.

R2 can be small since the voltage divider formed by R2/CR1 under
overload isn't allowing much into the device's diodes because its
'source voltage' is going to be less than a volt.

Yes, this is exactly how I do it.

Now if the line to be

protected is an output that must drive a stiff load R1 will be a
problem. The smaller you have to make R1 the larger the protection
diodes have to be in terms of peak current capability. You can devise
very fancy protection schemes beyond the diode approach but when dealing
with multiple data lines the cost situation can get out of hand.

Yes.

Protecting the rails is pretty easy. For example, a big old FET driven
by a reference such as the TLV431 (that one costs under a quarter a
pop). Set the resistor divider to wherever you want the rails to top
off. Just remember that prolonged exposure would cause a FET to start
glowing pretty quickly unless cooled. If you want the fuse to blow under
that condition you can fire a crowbar circuit instead of holding things
down with FETs.

Zener, TVS, MOV are not really to my liking in a situation where the
voltage differential between normal operation and catastrophe is around
a volt or so.

That's my feeling as well. I hadn't considered the FET approach. I
have used crowbars at times. On one buffer, I have 200mA SMD fuses so
if the overload into the output is continuous instead of just ESD, it
will blow to preotect the rest of the system.


Good day!






--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarle@sandia.gov -- NOTE: Remove "BOGUS" from email address to reply.

 

[Mark Jones]

Randy McLaughlin wrote:

"Mark Jones" <abuse@127.0.0.1> wrote in message
news:aIKdnTKbZ4OGA3PcRVn-tw@buckeye-express.com...

Rich Grise wrote:

On Mon, 17 Jan 2005 16:22:23 -0600, John Fields wrote:

On Mon, 17 Jan 2005 15:51:24 -0600, John Fields
jfields@austininstruments.com> wrote:

Ooops... Bad rhyme:


And so that family survives, a drunk, a whore, four ruined
lives, but Rhyanon's the happiest of lads, he's got a brother
and two Dads!

--- Somewhat better:

And so that family survives, a drunk, a whore, four ruined lives,
but R's the happiest of lads, he's got a brother and two Dads!


No, the rhyme's fine - the prob. is with the scansion. You might
have to look that word up - I'm not sure if I've invented it or
not.

John Fields, he done wrote us a poem. The newsgroups, about he does
roam. But when he gets smart, Not just a brain fart, I think we
should all just go home.

Thanks, Rich



HA!

Indeed, this "grown-ups-participating-in-kiddy-smack" is getting old.



Please stop cross posting.

Randy

I think Randy must be a bot also...

Wait, wait, let me guess: "Please stop cross posting." Yep, I knew it!

 

[Andrew]

Mark,

First of all, thanks for bearing with me!

Secondly, the motor definitely is too hot. The housing of the motor
reached 225 degrees F after 3 hours of operation at 50% duty cycle.
This 225F is roughly 107C, which translates to roughly 203C in the
rotor, where the maximum rating for the motor is 155C.

The 3 hour test run consisted of 15 seconds drawing roughly 3 amps, 15
seconds drawing roughly 1 amp. This continued with roughly a 1 second
pause in between each cycle. The test setup was an arm with a 15lb.
weight on the end. All torque specs for this setup were calculated,
and the torque necessary to lift the arm is well below the maximum
continuous rating for this motor.

The motor is a high quallity brushed DC motor designed for continuous
use at 6A, 24V, max. The specs can be found here:

http://www.maxonmotorusa.com/files/catalog/2004/pdf/04_082_e.pdf

It the red column, 148867 motor.

From reading around at many sites, it seems that the inductance of this
motor is very low, and to use it with a PWM signal, the inductance

needs to be increase (by a DC choke). Maxon (the motor company) sells
some chokes, and indicates that they are necessary to be used with the
motor driver that they also sell and recommend for this motor.

I believe that with the driver that I am currently using, I need this
choke. With the inductance I currently have (no choke, just the
motor's 80uH), I am generating 9.71W due to the current ripple (via the
formula I posted earlier, assuming it is correcct). Dissipating this
9.71W raises temperature at the rotor (above the ambient) by roughly
123C more than ideal (ideal being no loss, 0W generated due to current
ripple). This temperature rise, coupled with the temperature rise that
is associated with the current flow through the windings (roughly 54C
for the application) brought the temperature well above the maximum
(brought it to over 202C assuming 25C ambient, where maximum rating is
155C).

Raising the inductance by 470uH (with a DC choke), raises total
inductance to 550uH, which changes the power generated by the current
ripple to 0.21W, reduced by a factor of over 46x! The new temperature
rise is roughly 2.6C, this is down from 123C! The new total
temperature rise of the rotor is 56.6C, making the rotor roughly 81C,
which is much more reasonable).

Hopefully my calculations are correct, and adding this DC motor choke
to increasea inductance will decrease the current ripple power loss and
in turn decrease the heat generated in the motor. I will let you know
how it goes.

 

[Joerg]

Hi Chris,

Maybe the current would actually be tolerable since they might be
beefier than the input diodes, but who knows? These parameters are
unspecified. Thus, one has to fall back to the continuous current
absolute ratings if you want documented proof that it's protected.

They often aren't any beefier and, for example, the HC04 abs max spec
states 20mA for the input diodes and the same for the output diodes. So
that might indicate that pulse ratings are similar. Thing is, once one
of these beasts goes into latch up it doesn't matter what the diodes
could have been able to deal with. Unless VCC is taken away immediately
it's like crashing through ice.

Appnotes from TI that might interest you in this matter:

sdya009c
sdya012

A good family spec helps, too, but here I prefer ye olde data book and a
nice cup of coffee to study that kind of material. But I guess these
would be online as well.

Regards, Joerg

http://www.analogconsultants.com