Chip with simple program for Toy

[John Larkin]

On 18 Oct 2004 04:06:21 -0700, tatto0_2000@yahoo.com (Wong) wrote:

tatto0_2000@yahoo.com (Wong) wrote in message news:<509bfe22.0410150112.7c079369@posting.google.com>...
Hi,

Is it possible to saturate the NPN BJT transistor in this biasing ?
Vcc
___
|
|
|
_| C
B |
---- Resistor ----|
|
-
| E
|---------------- Output
|
Resistor
|
|
|
---
- Ground


Since the transistor is OFF when '0' to base and hence output is '0'.
Then when '1' to base I would like to have 4.5V at the output, is that
possible to bias the transistor in saturation region (since Vce no
more <0.2V)?

OK, one more question.
If my transistor datasheet stated that the minimum hFE (DC current
transfer ratio) is 100 and the maximum is 400, can I still force this
transistor into saturation where hFE normally is 10 in saturated
transistor?

Thank you.

Yup. If you jam in 1/10 as much base current as the load current, that
would be called a "forced beta" of 10.

But more base current doesn't always lead to lower saturation voltage.
For either the normal or inverted setup, there's some base current
that makes for the lowest Vce. A forced beta of 10 should be pretty
good, though.

John

 

[CFoley1064]

Subject: PCB header pins & connectors for amateur?
From: "mark.mcgee@csfb.com" mark.mcgee@csfb.com
Date: 10/18/2004 7:36 AM Central Daylight Time
Message-id: <1098102991.141487.152470@f14g2000cwb.googlegroups.com

Hi

Is there available a PCB header pin set, with matching socket which can
be assembled by an amateur without expensive specialist tools?
Regards,
Mark

Been there, done that. If you're on a tight budget, one thing you might try is
using standard .100" solid headers and Molex KK Series crimp terminal housings
with .100 crimp terminals. Yes, I know you need a custom hand crimping tool
for the crimp terminals ($180.00 USD), but a little deft use of a needlenose
pliers will allow you to fold over the sides of the terminal on the stripped
stranded wire and the wire insulation just like the tool, except without the
gas-tight crimp. You then use the tiniest bit of solder to solder the wire and
the terminal housing. If you're crafty, you can avoid getting solder all over
the place underneath, and it will fit into the housing nicely. If not, just
cut it off and try again. The key to this is not to have excess wire or a
solder blob hanging down beyond the crimp -- that gums up the action of the
terminal. Also avoid getting flux on the mating surface of the terminal.

The Mouser part numbers you would need for a 3-pin programming plug are:

538-08-52-0123 Crimp Terminals (3 ea.) $0.09 ea. (buy a few extra to
practice)
538-22-03-2031 .100" Verical solid header, 3-pin (1 ea.) $0.18 ea.
538-22-01-2037 .100" crimp terminal housing (1 ea.) $$0.25 ea.

As long as you use the phosphor bronze terminals with tin flash, you should be
good for at least a hundred reliable insertion/extraction cycles. Don't jam
the terminal into the housing. If it doesn't fit easily, you've either got it
backwards or you got excess solder under the fold of the terminal. Use an
xacto knife to push the little spring holder in to remove the terminal from the
housing.

By the way, the above parts don't have reverse polarity protection -- least
expensive solution here. If you're doing it yourself, be careful. If a
customer is doing it, go with the polarized housings and headers or use a
polarizing key and cut off one of the pins. Go to mouser.com and look for
yourself -- look up p. 807 of the current catalog.

Chris

 

[CFoley1064]

Subject: Re: using a 7809 voltage regulator
From: John Fields jfields@austininstruments.com
Date: 10/23/2004 3:10 PM Central Daylight Time
Message-id: <vceln0p3ec7ui2ahveiv9oaveci12jafml@4ax.com

input voltage to the 7809 below 12.5V, otherwise it won't work right. The
wall
^^^^^ ^^^^^
above 11V typ.

How did I write that??? Jeez -- I must have gremlins in the keyboard.

Let's see -- I added 9 + 2.5 and got 12.5, and then used below instead of
above?? Senior moment. You're right, of course.

Thanks.
Chris

 

[J M Noeding]

On Sun, 17 Oct 2004 15:00:49 +0100, "Airy R. Bean" <me@privacy.net>
wrote:

It's been the case in Britland for many years now, that if you
want info to build modern gear, then buy the ARRL handbooks.
OTOH, if you want a mediocre book that is many
years out of date and seems to owe more to self-congratulation than
it does to technical excellence, then go for the RSCB offering. Odd, really,
when you consider that the RSCB is a publishing corporation.

I do not agree, and soon the RSGB is the only IARU organization I

support, have been a member from january 74. They now contribute with
a lot of useful material, but it was different earlier, as one had the
feeling that high-ranked persons or duke and knights with outdated
experience was telling you what to do.

But for Radcom, I must admit that I mainly read G3VA's "Technical
topics"

My radio club was Worcester &DARC, suppose it is not so much activity
there now....

---
J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm

 

[R. Steve Walz]

Karl-Hugo Weesberg wrote:

They are hungry and eat all electronic parts!

Dangerous!
-----------

Go the shit back to school; get a fucking job!

-Steve
--
-Steve Walz rstevew@armory.com ftp://ftp.armory.com/pub/user/rstevew
Electronics Site!! 1000's of Files and Dirs!! With Schematics Galore!!
http://www.armory.com/~rstevew or http://www.armory.com/~rstevew/Public

 

[john jardine]

"Airy R. Bean" <me@privacy.net> wrote in message
news:2tf8jbF1ufesdU1@uni-berlin.de...

Question - what is the internal modelling technique used
by these various programs, and can we produce our own package?

Is it based upon successive delta-time increments, and if so, what
is the increment? What prompted the last question is an attempt
I made to create a sine-wave generator using the identity that
sin dTheta = dTheta, but I had to go for an _extremely_ small
value of dTheta (ISTR 10^ -18) before getting anything like a
decent sine wave, and even that degenerated after a few cycles.

So, these circuit simulators - what is their underlying technique
for circuit simulation?
[clip]

The simulators basically offer 2 types of direct analysis ...
An "AC" analysis and a "Transient" analysis. Their answers come via
different maths methods.
Basically the much less useful 'AC' analysis examines all the wire
connection points 'nodes' in the circuit diagram and enters the found
components in 2 matrices. Each (square) matrix is sized to hold node^2
elements. One is for 'real' components, the other for quadrature components.
All non linear components in the circuit must first be simplified/replaced
by linear equivalants (messy). Matrices are filled in a manner similar to
kirchoffs loops anaysis. Reactive components entering the imaginary matrix.
Ie lots of real/imag simultaneous equations need solving which is of course
why the computer is handy.
After they are filled the matrices are mathematically inverted to give a
complete set of solved phase and ac voltage data for all the node points in
the circuit. Nice for filters useless for oscillators!.

The more useful transient analysis is similar to as you mention (Babbage's
difference engine?) but based simply on the differentials V=L i/t and V=i/C
and uses near complete maths models for the semicons or other non linear
elements. Nodes examined in turn and time steps selected purely on the
basis of how fast the results are changing. time steps can be a problem as
too long and the final results get 'smeared out' hence phase lag artifacts
cause overall loop stability problems.
The TA is conceptually very simple and surprisingly easy and fun to
programme for set piece or well observed circuits but gets *really* spagetti
code messy if it is to work smoothly with any input circuit. Big problems
can turn up getting the results to converge or balance and much progging
effort is needed in this direction.
regards
john

 

[john jardine]

"J M Noeding" <la8ak@online.no> wrote in message
news:dc15n0dima7ip954c5tf35vp9v9efraoe2@4ax.com...

On Sun, 17 Oct 2004 15:00:49 +0100, "Airy R. Bean" <me@privacy.net
wrote:
[clip]
But for Radcom, I must admit that I mainly read G3VA's "Technical
topics"

My radio club was Worcester &DARC, suppose it is not so much activity
there now....

---
J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm

To me, Pat Hawker is the defining spirit of UK amateur radio.
I've also picked up much fascinating stuff from his technical-topics and the
mentions of his SOE work in WW2.
regards
john

 

[peterken]

There's another very good reason for not putting data together with mains,
it's called safety..... :-S
Minimal distance is 30cm if no wiring tubes are used over the individual
lines.

And indeed, voltage spikes on mains *might* momentarily disrupt data
traffic, or even damage databuffers due to induced spikes




"Rene" <nospam@nospam.nospam> wrote in message
news:qvUed.522650$8_6.77461@attbi_s04...
I was told that it is not a good idea to run a power (120 AC) cable together
with an Ethernet cable because the AC cable would disrupt the transmission
on the Ethernet cable.



Is this true? If tit is, is there a way to have the power cord shielded so
that it does not bother the Ethernet cable or vise versa? Can I buy cables
that already include a shield on them?



Thank you.

 

[Clarence]

"Rene" <nospam@nospam.nospam> wrote in message
news:qvUed.522650$8_6.77461@attbi_s04...

I was told that it is not a good idea to run a power (120 AC) cable together
with an Ethernet cable because the AC cable would disrupt the transmission
on the Ethernet cable.

Is this true? If tit is, is there a way to have the power cord shielded so
that it does not bother the Ethernet cable or vise versa? Can I buy cables
that already include a shield on them?

Thank you.

Electrical code does not permit power and low voltage signals to run in the

same conduits or channels. Shielded or not.

Interference? Not much, I would guess.

 

[Roy Lewallen]

When solving node/loop equations manually, it's generally necessary to
resort to phasor analysis with its underlying assumptions, or Laplace
transforms. The latter does have the capability of producing a time
response. But the solution requires finding the inverse transform, a
process similar to integration in that there's no single direct rule,
and often it's impossible to find a solution except for simple cases.

Computers can be programmed to solve complex problems numerically, using
fundamental time-domain current/voltage relationships (such as the
relationship V(t) = L di/dt for an inductor, or even more generally,
V(t) = L di/dt + I dl/dt for a time-varying inductance). This is
basically what SPICE does, and it's able to easily solve problems which
are simply not possible to do manually, either because of the enormous
time that would be required, or the impossibility of finding a reverse
Laplace transform -- or its equivalent, the solution to a high-order
differential equation if Laplace transforms aren't used. A google search
on 'SPICE "time step" equations' brought a number of hits. I'm sure you
can find an adequate explanation of the inner workings of SPICE among them.

Roy Lewallen, W7EL

Steve Nosko wrote:

. . .
Correct me if I am wrong (like I need to say this here, eh?)
I believe the underlying basis is the collection of loop / node equations
used (by Engineers) to model circuits. We know the behavior of resistors,
inductors and capacitors and have mathematical models for them. To this we
add the active devices, etc. and develop an "engine" which does all the
calculations for us. [[we used to do them by hand/slide rule -- yes, I am
included in this we]]. These loop and node equations provide us with a
mathematical model of the behavior of electronic circuits. If done
carefully, this is a general purpose model which applies to all the
situations for which our component models are valid.
Some time later there were bare engines into which we had to type the part
values and node numbers (the sane things you can see in printouts from
Spice). As computers got more powerful, schematic entry was developed. I
believe these programs to be very useful, but as with any model or
simulation, it is best to understand the limitations.
Thre is an alternate method. It is also possible to derive equations for
each type of situation and use these calculations each time you need to
solve that type of problem. I am sure you are familiar with the equations
for things such as parallel capacitors and resonance and so forth. These
are specific solutions of the properties of components in those specific
circuits.
. . .

 

[peterken]

Easiest and most accurate solution is using the "voltage divider" with two
resistors connected to the reference.
Use 0.1% resistors.

#1 requires an extra reference, including its tolerances, thus requiring
calibration
(AD has its own internal reference, thus compensating its own
measurments)
#2 would be the solution (if ADC doesn't sink enough, take for example order
of 10k)
Any arising voltage drops due to the R- network can be incalculated in
software
#3 has the disadvantage of different leakage currents for every device, thus
requiring calibration


"thomas" <none@yahoo.com> wrote in message
news:Ttaed.3156$Ag.2240@fe37.usenetserver.com...
I have a AD594 temp sensor (~10mV/C output) connected to the 10bit ADC on an
AVR. The sensor output will be -375mV to +1015mv for the temperature range
(-40C to +100C) I'm interested in. The ADC only accepts +V analog input so
I'll need to bias the signal 'up' a little to get it above 0V. If possible
the solution should be repeatble in production and not require individual
calibration.

Specs:
Using a TC7660 or TCM829 for the negative supply to the AD594.
I'm using the internal 2.56V Vref of the AVR ADC. Vref is exposed on a pin.
The AD594 can source 5ma on its output.
The ADC has 100M input resistance.

Googling came up with the following suggestions:
#1)Add a low voltage reference in series to temperature sensor.

#2) Try connecting the output of the temp sensor to the ADC through a 1k
resistor. Take another 1k resistor and connect it between the reference
voltage and the ADC input. This may not work if your temp sensor will not
sink enough current.

#3) Many ADC's have voltage reference outputs that can be used to bias the
analog input(s) of the ADC. This can be done by connecting a resistor from
the ADC reference output to the analog input. The Voltage reference output
can be bypassed to analog ground with a small capacitor to improve the
ripple rejection. The bias resistor value can be selected based upon the
ADC input leakage current. Consider a resistor value such that the maximum
ADC input leakage current alone causes less than a 1 LSB voltage across the
bias resistor. In this way the "offset code" of the ADC will not be overly
input bias current dependent.

#1 seems straight forward enough, however, #2 only requires two resistors
and #3 only one.

Questions:
- Is one or is two resistors the better solution?
- #3 gives specifics on selecting the resitor value. Any help with this, I'm
lost?

thx,
t

 

[Clarence]

"oddsod" <SPAMCAN2004-PRIVATE1@YAHOO.COM> wrote in message
news:fedf4b45.0410250016.55fd17e0@posting.google.com...

http://w1.706.comhem.se/~u70624934/

You have way too much time on your hands.

Nothing of value here!

 

[John Fields]

On Mon, 25 Oct 2004 16:02:51 GMT, "Clarence" <no@No.com> wrote:

"oddsod" <SPAMCAN2004-PRIVATE1@YAHOO.COM> wrote in message
news:fedf4b45.0410250016.55fd17e0@posting.google.com...
http://w1.706.comhem.se/~u70624934/


You have way too much time on your hands.

Nothing of value here!

---

Something of value _there_, however.

--
John Fields

 

[Mark Fergerson]

oddsod wrote:

http://w1.706.comhem.se/~u70624934/

Snort

A strap-on in bild03!

Yeah, way too much time on your hands.

Mark L. Fergerson

 

[peterken]

"Power" means "electrical dangerous voltage-levels", in Europe the
"dangerous level" is set to 48V.
Usual indication of "power lines" in this context is "mains supply"...


"Rene" <nospam@nospam.nospam> wrote in message
news:F99fd.526556$8_6.370600@attbi_s04...

Electrical code does not permit power and low voltage signals to run in
the
same conduits or channels. Shielded or not.

Not even if power is only 12 volt DC?

 

[Rene]

That is fine how ever, pulsing loads on the DC line could
induce cross talk problems in crappie communication cables like
CAT5 and the like over a long hall.

Even if the CAT5 cable is shilded?

 

[Jamie]

peterken wrote:

"Power" means "electrical dangerous voltage-levels", in Europe the
"dangerous level" is set to 48V.
Usual indication of "power lines" in this context is "mains supply"...


"Rene" <nospam@nospam.nospam> wrote in message
news:F99fd.526556$8_6.370600@attbi_s04...

Electrical code does not permit power and low voltage signals to run in
the
same conduits or channels. Shielded or not.


Not even if power is only 12 volt DC?

That is fine how ever, pulsing loads on the DC line could
induce cross talk problems in crappie communication cables like
CAT5 and the like over a long hall.

 

On Thu, 21 Oct 2004 14:02:51 +0100, "James Varga"
<james@jamesvarga.com> wrote:

Okay - I've started trying to make some d/s boards and have run into
another
funny. It seem that the image after developing is 'smudged' - its not
actually smudged but it looks like that. It looks like the image is
missing
an area like it has been rubbed off or something.

This is as good as I've gotten it so far - as you can see there is still a
problem with the second side, although the one side is perfect. Each step is
done vertically so I'm really struggling to figure out whats going wrong.

http://www.jamesvarga.com/projects/beblu/pcbtest3.jpg

Any ideas?

You might try PhotoEZ stencils ...

http://www.photoez.itcstore.com/



Shirley (circuit bridge)

Shirley
..
http://www.photoez.itcstore.com/

http://stores.ebay.com/PhotoEZ-Silkscreen-Stencil

 

[BobGardner]

Either a low cost purchased unit, or the schematics to build one.
I am trying to detect in the 0- 30Hz range.
============================

So how about a loop antenna, an instrumentation amp, and a 30 hz active lp
filter and a scope?

 

[BobGardner]

I've
googled endlessly to try and find a chip that has the same function as
either of these but I'm drawing a blank.

How about 2 or 3 CS3310 dual spi controlled log dacs? Better specs (digital not

analog)