Simplest latch imaginable

Fred Bloggs wrote:
CRY-BABY MOLLIFIER



---+--------+
| |
| \
| 10k
| \
e /
\| |
2N2907A |------+
/| |
c |
| 1N5817 |
| - |
+--|>|---+
| - |
| |
| c
| |/
+------| 2N2222A
| |\
\ e
10k |
\ |
/ |
| |
----+--------+
Click to expand...
I stared at this for a long time. Still can't figger out what the diode
does. Depending on the source impedance, the base is gonna melt or the
bond wire will blast off long before the diode turns on??? Yes? No?
Stated another way, I ain't mollified.
Won't a couple of base resistors protect the base?
mike


--
Return address is VALID.
Bunch of stuff For Sale and Wanted at the link below.
Toshiba & Compaq LiIon Batteries, Test Equipment
Honda CB-125S $800 in PDX
Yaesu FTV901R Transverter, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/
 
"Winfield Hill" <Winfield_member@newsguy.com> wrote in message
news:c6mojd01phv@drn.newsguy.com...
Winfield Hill wrote...

And surely 16 cents cannot be an issue.

Aha! I found them at 7.8 cents, so there!

Thanks,
- Win

whill_at_picovolt-dot-com (use hill_at_rowland-dot-org for now)
Click to expand...
I sit corrected.....but can I buy 5 different parts from 5 different
manufacturers that fit in the same space.....

Great to see examples using specified device ratings. IMO its what
distinguishes the engineer from the hacker, and differentiates the
production success from the nightmare.
 
On Thu, 29 Apr 2004 19:01:04 -0700, the renowned "Terry Given"
<the_domes@xtra.co.nz> wrote:

"Winfield Hill" <Winfield_member@newsguy.com> wrote in message
news:c6mojd01phv@drn.newsguy.com...
Winfield Hill wrote...

And surely 16 cents cannot be an issue.

Aha! I found them at 7.8 cents, so there!

Thanks,
- Win

whill_at_picovolt-dot-com (use hill_at_rowland-dot-org for now)


I sit corrected.....but can I buy 5 different parts from 5 different
manufacturers that fit in the same space.....
Click to expand...
The 2N506x is a jellybean part, made by a bunch of manufacturers.
On Semi, Teccor, Central Semi, ST, Philips (there's 5). They have been
around (and reasonably priced) for maybe 30 years that I know of, and
are still going strong.

Eg. http://www.onsemi.com/pub/Collateral/2N5060-D.PDF

Note: "preferred device"

The only gotcha to be a bit careful with is the Vdrm rating of
30V/usec typical, so a bit of snubbing might be required in some
applications.

Great to see examples using specified device ratings. IMO its what
distinguishes the engineer from the hacker, and differentiates the
production success from the nightmare.
Click to expand...
You mean you don't just start production if the prototype works? ;-)

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
 
"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:bea190lgujbe847agfj19n95og27424ag2@4ax.com...
On Thu, 29 Apr 2004 19:01:04 -0700, the renowned "Terry Given"
the_domes@xtra.co.nz> wrote:

"Winfield Hill" <Winfield_member@newsguy.com> wrote in message
news:c6mojd01phv@drn.newsguy.com...
Winfield Hill wrote...

And surely 16 cents cannot be an issue.

Aha! I found them at 7.8 cents, so there!

Thanks,
- Win

whill_at_picovolt-dot-com (use hill_at_rowland-dot-org for now)


I sit corrected.....but can I buy 5 different parts from 5 different
manufacturers that fit in the same space.....

The 2N506x is a jellybean part, made by a bunch of manufacturers.
On Semi, Teccor, Central Semi, ST, Philips (there's 5). They have been
around (and reasonably priced) for maybe 30 years that I know of, and
are still going strong.

Eg. http://www.onsemi.com/pub/Collateral/2N5060-D.PDF

Note: "preferred device"

The only gotcha to be a bit careful with is the Vdrm rating of
30V/usec typical, so a bit of snubbing might be required in some
applications.
Click to expand...

voila.

Great to see examples using specified device ratings. IMO its what
distinguishes the engineer from the hacker, and differentiates the
production success from the nightmare.

You mean you don't just start production if the prototype works? ;-)
Click to expand...
no, not at all. I worked on an existing mil UPS design in the states a few
years back. Many battery failures started occurring, so I looked at the
charger - a simple flyback converter with closed-loop voltage regulation,
and a current limit too. All seemed well. Then I measured its behaviour, and
found appalling line regulation - from 115Vac to 230Vac caused the output
voltage to change dramatically, around 50% IIRC. But at 115Vac in, Vout
happened to be right......obviously load regulation was appalling too.

Feedback was opto via TL431, I forget how the current limit worked exactly,
but through the same opto. how could it not regulate?!? This was designed by
the VP of eng, a twit with an ME from MIT, and no real skill. basically they
turned it on, it didnt explode, the voltage looked right, so they shipped
it!

close examination showed a host of layout problems, but the main culprit was
the ultra-slow rectifier diode (Trr spec anyone?) which successfully managed
to use up all the gain margin in the closed-loop controller.

speaking of which, closing a loop can do some interesting things. If you
think about closed-loop response to a disturbance, you can "inject" that
disturbance anywhere you like - for example a load change. Alternatively,
you can build a "self-disturbing" controller by screwing up the calculations
(or the circuit ;) - effectively injecting a disturbance in a different part
of the loop.

If loop gain is high enough, it will STILL WORK! Of course when doing
transient tests you'll get a worse response, as the control loop is busy
dealing with the self-inflicted problems - hence my comment about gain
margin.can be hard to diagnose, as the system works but with degraded
performance. I did this with a 200kW 3-phase inverter/rectifier controller -
I had a wide variety of screw-ups in my code (sine routines overflowing,
etc) yet it all worked, but not as well as expected. I went thru and
individually calibrated all my maths routines, and found some astonishing
errors - about 20 degrees of my sine calculation overflowed due to crap in a
look-up table, yet my PLL (sync. ref. frame PI controller really) worked
brilliantly, and the UPS wasnt too shabby - 10% load regulation. Given that
the sine routine was used to calculate the PWM switching times, i.e. the
overflow resulting in a burst of incorrect PWM for 20/360 = 5% of the time,
this is quite remarkable!
 
mike wrote:
Fred Bloggs wrote:





CRY-BABY MOLLIFIER



---+--------+
| |
| \
| 10k
| \
e /
\| |
2N2907A |------+
/| |
c |
| 1N5817 |
| - |
+--|>|---+
| - |
| |
| c
| |/
+------| 2N2222A
| |\
\ e
10k |
\ |
/ |
| |
----+--------+


I stared at this for a long time. Still can't figger out what the diode
does. Depending on the source impedance, the base is gonna melt or the
bond wire will blast off long before the diode turns on??? Yes? No?
Stated another way, I ain't mollified.
Won't a couple of base resistors protect the base?
mike
Click to expand...
It is assumed that the circuit is in series with a current limited load
- like 200mA. The diode clamps the forward bias of both b-c junctions
simultaneously to approximately 0.25V at this current, preserving
significant hFE in the transistors- as much as 20 @500mA Ice, so that
the base current is now limited to Ice/hFE or about 5mA in this
application. Now the majority of current flows through the
EC,pnp->CE,npn path, so that the total voltage drop is ~ 2x Vce +Vdiode
, and Vce~Vbe,sat-Vdiode for a total of 2xVbe,sat-Vdiode where Vbe,sat
is the BE voltage at the edge of saturation for Ic=200mA- approximately
the same for both transistors. The circuit can be used safely to switch
as much as 500mA. Without the diode, the current splits into two
parallel paths (EC,pnp+ BE,npn)||(EB,pnp+CE,npn) and the split will be
essentially equal since the transistors are complementary- so that
contrary to WHill's slander, it is quite safe and reliable at 200mA.
There is no need for series base resistors and they would only serve to
greatly increase the on-voltage across the circuit. Also, the Schottky
does tend to leak profusely so that the base pulldown resistors should
be reduced to something like 470 ohms - reducing triggering sensitivity
which is a non-issue in this case. The thread was all about another
failed attempt at slander by Hill: first knock the circuit for using one
extra part, then knock the circuit on the technical merits implying the
basic topology is unsalvageable, then get butt handed back to himself,
then return to knock circuit on using one extra part, etc...
 
Terry Given wrote:

Great to see examples using specified device ratings. IMO its what
distinguishes the engineer from the hacker,...
Click to expand...
Any day of the week , FLAKE! It is my observation that the sorriest
excuses for engineers are the weakling maggots who have no analytical
abilities, AND NO TALENT FOR INVENTION OR SYNTHESIS, who always insist
on using the HACK standard part for the HACK standard application, to do
their HACK standard job.
 
Fred Bloggs wrote...
... The thread was all about another failed attempt at slander
by Hill: first knock the circuit for using one extra part, then
knock the circuit on the technical merits implying the basic
topology is unsalvageable, then get butt handed back to himself,
then return to knock circuit on using one extra part, etc...
Click to expand...
WRONG, as usual when you overly defend an awkward circuit.

To Ken Smith's question four days ago, "Why build an SCR when
they can be bought in a TO-92 package?" I simply commented
in response, "Indeed, e.g., 2n5062, 16 cents each. X0202MA,
52 cents each." And later, "Aha! I found them at 7.8 cents."

That, and my comment, "While a BJT base can take higher current
than one might imagine, this is not a good situation." And I
also posted the one available 2n2222 maximum base-current spec,
comparing it to the 10A spec for the TO-92 jelly-bean SCR.

And finally my version of Fred's circuit, illustrating the
elegant simplicity allowed by using a real honest SCR.

.. SHUNT
.. +--o ARM o SAFE o---+
.. | | |
.. +-+--/\/\---+---o~~~~o--+------/\/\--------,
.. | 100K | ignitor R1 |
.. | | _|_
.. --- | _\_/_
.. - 9V | / 220 /|
.. | +----------o o----/\/\---+--' | 2n5061
.. | | sw | | 2n5064
.. | === 0.47u 470 |
.. | | metal film | |
.. +-----------+-------------------------+----'

I labeled this circuit, "smaller, cheaper, better performing,
more reliable, more simple, more sensible." Accurate points.

None of this is slander, it's calm engineering discussion.


Thanks,
- Win

whill_at_picovolt-dot-com (use hill_at_rowland-dot-org for now)
 
Winfield Hill wrote:

None of this is slander, it's calm engineering discussion.
Click to expand...
Not aiming this at you Win, but have you ever noticed how many engineers
have the ability to utter relationship-ending things without ever realizing
it?

--
John Miller
Email address: domain, n4vu.com; username, jsm

Stability itself is nothing else than a more sluggish motion.
 
"John Miller" <me@privacy.net> wrote in message
news:c6r2uc$d8d$1@n4vu.com...
Winfield Hill wrote:

None of this is slander, it's calm engineering discussion.

Not aiming this at you Win, but have you ever noticed how many engineers
have the ability to utter relationship-ending things without ever
realizing
it?
Click to expand...
He (engineer): Have you changed your hair?
She: Do you like it?
He. Makes you look fat.
 
Winfield Hill wrote:
Fred Bloggs wrote...

... The thread was all about another failed attempt at slander
by Hill: first knock the circuit for using one extra part, then
knock the circuit on the technical merits implying the basic
topology is unsalvageable, then get butt handed back to himself,
then return to knock circuit on using one extra part, etc...


WRONG, as usual when you overly defend an awkward circuit.

To Ken Smith's question four days ago, "Why build an SCR when
they can be bought in a TO-92 package?" I simply commented
in response, "Indeed, e.g., 2n5062, 16 cents each. X0202MA,
52 cents each." And later, "Aha! I found them at 7.8 cents."

That, and my comment, "While a BJT base can take higher current
than one might imagine, this is not a good situation." And I
also posted the one available 2n2222 maximum base-current spec,
comparing it to the 10A spec for the TO-92 jelly-bean SCR.

And finally my version of Fred's circuit, illustrating the
elegant simplicity allowed by using a real honest SCR.

. SHUNT
. +--o ARM o SAFE o---+
. | | |
. +-+--/\/\---+---o~~~~o--+------/\/\--------,
. | 100K | ignitor R1 |
. | | _|_
. --- | _\_/_
. - 9V | / 220 /|
. | +----------o o----/\/\---+--' | 2n5061
. | | sw | | 2n5064
. | === 0.47u 470 |
. | | metal film | |
. +-----------+-------------------------+----'

I labeled this circuit, "smaller, cheaper, better performing,
more reliable, more simple, more sensible." Accurate points.

None of this is slander, it's calm engineering discussion.


Thanks,
- Win

whill_at_picovolt-dot-com (use hill_at_rowland-dot-org for now)
Click to expand...
I told you that there was no comparison between the SCR and
dual-transistor circuit other than ease of implementation-everyone in
the world has a 2n2222/2907 somewhere in their house whether they know
it or not-and those particular parts can be configured into numerous
circuits:
Please view in a fixed-width font such as Courier.




. SHUNT
. +--o ARM o SAFE o---+
. | | |
. +-+--/\/\---+---o~~~~o--+---+----/\/\---------+
. | 100K ignitor | | 22 |
. | | e |
. --- | \| |
. - 9V | +--/\/\---------+
. | | /| 1K |
. | +-----------+ c |
. | | | |
. | | | c
. | | / | 220 |/
. | +------o o-----+--/\/\---+-----|
. | | sw | |\
. | === 0.47u 470 e
. | | metal film | |
. +-----------+-------------------------+-------+
.
 
John Miller wrote...
Winfield Hill wrote:

None of this is slander, it's calm engineering discussion.

Not aiming this at you Win, but have you ever noticed how many
engineers have the ability to utter relationship-ending things
without ever realizing it?
Click to expand...
Yeah, well, you you you... John Miller... just watch your step!!

:>)


Thanks,
- Win

whill_at_picovolt-dot-com (use hill_at_rowland-dot-org for now)
 
On Thu, 29 Apr 2004 09:16:34 -0700, "Richard Henry" <rphenry@home.com>
wrote:

"John Miller" <me@privacy.net> wrote in message
news:c6r2uc$d8d$1@n4vu.com...
Winfield Hill wrote:

None of this is slander, it's calm engineering discussion.

Not aiming this at you Win, but have you ever noticed how many engineers
have the ability to utter relationship-ending things without ever
realizing
it?

He (engineer): Have you changed your hair?
She: Do you like it?
He. Makes you look fat.
Click to expand...
As one who has sustained/survived 44 years of marriage, the correct
response is....

He (engineer): Have you changed your hair?
She: Do you like it?
He. I liked the other style MUCH better.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
You may feel good about it but I don't. Fred talks about 200mA currents,
and yet the ABSOLUTE maximum spec for a 2N2222 base current is 200mA.
That's too close for me, I prefer the SCR's 10A max spec safety margin.
Click to expand...
There is no such rating- even the P2N2222A from ON is rated at 600mA IC
continuous- and Fairchild rates theirs at 1.0A.
 
in article 4782640f.0404240657.604e08ce@posting.google.com, Aubrey McIntosh
at mcintosh@spam04.vima.austin.tx.us wrote on 4/24/04 09:57:

mtbrecyclebin@hotmail.com (MTB) wrote in message
news:<9da81cc6.0404240059.5940133@posting.google.com>...
Hi,

I want to ignite the second stage of a model rocket by using a mercury
switch to detect the deceleration of the first stage motor stopping.

Some people are *very* afraid of mercury. There are many reports of
using evacuations and "Moon Suits" to clean up after broken
thermometers.
Click to expand...
I like to carry little bits of mercury around in my mouth. Gives a
glistening smile :)
DC
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top