Driver to drive?

[Joerg]

Hi Scott,

Indeed it does... draws about 40 or 50 ma, with < 10 of that being the MCU
and display. Didn't know that about MOVs - one more reason to find another
design.

I'd just go with a resistive divider and feedback. BTW, 10mA for uC and
LCD display sound a bit high as well. That alone would empty a regular
9V battery in under 24 hours. I guess it's too late now but next time I
would look into lower power uCs like the MSP430.

Regards, Joerg

http://www.analogconsultants.com

 

[Scott Miller]

If you go with the TL082 and don't need the buffer, then a good use for
it would be as low-pass filter and buffer for the 5V shown in the
schematic...this will eliminate your 5V switching noise from the MCU and
other digital switching you have going on there.

I'll probably try out the direct version and see how much noise it's got.
Would a simple RC network make an acceptable filter if there's a lot of
noise on the op amp output?

Ok, so I checked my parts bin and found a TL082. And now I see that it's a
DUAL op-amp, so I get the part about using the other one as a filter. Duh.
Ok, time to go experiment a bit.

Scott

 

[Jonathan Kirwan]

On Sun, 28 Nov 2004 15:09:10 -0800, "Scott Miller" <scott@3xf.com> wrote:

snip
The neon lamp tubes? I've seen that done. I'm using 250v varistors
instead. Doesn't seem like it would be any more efficient - it's still a
shunt regulator, and will put a constant drain on the PSU even when the GM
tube's not conducting, right?

Yeah, it used power. My supply for it, back then, was two 45V telephone battery
packs (bunch of 1.5V AA types in a package.) So I had 90V to work with and for
my needs the battery lifetime was just fine -- memory is thin and I've got it
packed away so I cannot easily verify, but I think it ran for about 8-10 hours.
I used it intermittently for testing rock samples (autunite, for example), so I
could be off by quite a bit.

Jon

 

[Harry Dellamano]

Ken Smith wrote:

IRC (the company, I do Recall Correctly) make some great smt resistors.
And have peak pulse power curves.

Caddock does too:
http://www.caddock.com/Online_catalog/smt/smt.html

--
John Popelish

Caddock is a perfect example of a poor surge (Pulse) power resistor. They
are thin film and X1.5 rated peak power. A good surge rated resistor is
X5000 or maybe 5 Joules. Call Richard Caddock and see if they speak in
Joules.

Cheers,
Harry

 

[Scott Miller]

With a serial controller on there? That is one heck of a deal. Much more
$$$ out here in Northern California :-(

Not serial, standard HD44780 parallel. I've got it running in 4-bit mode,
write-only, so it takes 6 I/O lines. I just checked my old emails - it was
a special from Electronic Goldmine, part number G14023, $1.49 each, back in
January. No such deals at the moment that I can see. I think I bought 10 -
should have gotten a few more.

Scott

 

[Scott Miller]

Yeah, it used power. My supply for it, back then, was two 45V telephone
battery
packs (bunch of 1.5V AA types in a package.) So I had 90V to work with
and for
my needs the battery lifetime was just fine -- memory is thin and I've got
it
packed away so I cannot easily verify, but I think it ran for about 8-10
hours.
I used it intermittently for testing rock samples (autunite, for example),
so I
could be off by quite a bit.

That sounds about right. My first design used a tube from an old Civil
Defense meter. Those things usually took B or lots of D batteries and
didn't last too long. I see counters today running for thousands of hours
on a single battery. Just wish I could find a schematic for one of those
supplies.

I've got a couple suggestions and an op amp to play with, so I'll probably
see what I can do tonight.

Scott

 

[keith]

On Sun, 28 Nov 2004 20:50:45 +0000, CBarn24050 wrote:

Subject: What do you think of this design?
From: Guy Macon http://www.guymacon.com
Date: 28/11/2004 13:44 GMT Standard Time
Message-id: <10qjlhl62bs6o98@corp.supernews.com


One of the fellows working for me designed this:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3856393230

It's a simple product, but any comments on the design of it
would be most appreciated.



Practicaly useless, no good as an accurate cap box as there is too much
unpredictable stray cap. No good at anything over video frquency due to self
resonance. Will emit and pickup all manner of emi. If that wasn't enough this
is a product that is allready in the marketplace for decades, invent something
^^^^^^^

Decades?

new!

--
Keith

 

[CFoley1064]

Subject: PC Board Kits
From: "Jim Douglas" james.douglas@genesis-software.com
Date: 11/28/2004 4:58 PM Central Standard Time
Message-id: <kf-dnR_08IwkxTfcRVn-hA@comcast.com

Any recommendations for kits, and were to get them for making PC boards
using the resist pen method? I would make 1-3 boards every couple of months
and they would not be all theat complicated.

Thanks!

JimD

Resist pens are only good for repair -- you immerse the board in etchant for 15
seconds or so, then examine traces for scratches. Using them to fabricate even
the simplest circuits is not a good idea.

If you're making single-sided boards in small quantities, and they're not very
demanding (say, 20 mil min. traces) look at using the laser printer/iron-on
method.

Chris

 

[David L. Jones]

Guy Macon wrote:

One of the fellows working for me designed this:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3856393230

It's a simple product, but any comments on the design of it
would be most appreciated.

I must say that it's not that great.
1/2/4/8 steps? that ain't all that useful and it isn't really a
"decade" box.
In a "resistor substitution" box you want either the preferred value
range, or better yet the more traditional "decade" box where you can
easily dial up a specific value.
A decade box is 10 of the same value in series, eg 10x10ohm, 10x100ohm,
10x1K, 10x10K, 10x100K etc

Presumably with this box you can parallel up the values?

Do a real deacde box and you might have something useful.
Regards
Dave

 

[Spehro Pefhany]

On Tue, 23 Nov 2004 23:02:01 GMT, the renowned James Beck
<jim@reallykillersystems.com> wrote:

In article <38g7q095njiqifbak6dlu6q7k238uhnraq@4ax.com>,
speffSNIP@interlogDOTyou.knowwhat says...
On Tue, 23 Nov 2004 17:11:58 -0500, the renowned Boris Mohar
borism_-void-_@sympatico.ca> wrote:

I use only one address but I fail to see why I could not have different
billing and shipping address.

That's a fraud indicator.


Best regards,
Spehro Pefhany

A lot of us use our personal credit cards, which have our home address
as the billing address, for "company" purchases, which get shipped to
the company. No fraud there. We have several customers that do that to
save the hassle of a COD package.

Jim

Yeah, I know. But crooks do it too, which screws it up for the rest of
us.


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

 

[Winfield Hill]

Robert Baer wrote...

A temperature compensated 500V zener would be far better...

Given the device physics, that would have to be made from 89
5.6V zener dies in series. :&gt (If a zener reference was
desired, it would make more sense to attenuate the HV down
to 5.6V, compare and regulate.)


--
Thanks,
- Win

 

[Harry Dellamano]

"Terry Given" <my_name@ieee.org> wrote in message
news:e20qd.14186$9A.271659@news.xtra.co.nz...

Hell yes. I learned this very early on, when placing damping resistors in
series with Y caps in big EMI filters. One day we noticed a flash of light
when we switched the prototype on. We switched it off, pronto. A thorough
set of diagnostics found no problem, but we weren't hallucinating so kept
looking. And the 1R 2W PR02 resistor I had in series with the 100nF Y cap
was open circuit. As were ALL of them, in all of the prototypes. We then
asked the peak-power question, which was something like (400V*1.41)^2/1R =
oh fuck, 314kW. And a carbon-composition resistor solved the problem. HVR
make some real good ones

Cheers
Terry
The same problems occur in surface mount film resistors which can only take

X10 power for short periods of time. Kamaya Ohm RPCNN and KOA SG73 series of
resistors can withstand up to 10KW in SM2512 packages. Ohmite has an ox/oy
series of leaded parts that can go to 80 Joules. Sure nice to see a Joule
rating in resistor spec. They are a must in any power electronics designer's
tool kit.
Cheers,
Harry

 

[Guy Macon]

David L. Jones wrote:

1/2/4/8 steps? that ain't all that useful and it isn't really
a "decade" box.

It's very useful indeed. The key is to understand binary math.

Lets say that you want a 3.65K resistor.
Set the 3 by turning on the 1 and the 2 on the 1000s decade,
set the 6 by turning on the 2 and the 4 on the 100s decade,
set the 5 by turning on the 1 and the 4 on the 10s decade.
For experienced engineers/technicians, this will come naturally.
For those just learning, the practice in binary to decimal
conversion teaches them something that they will use a lot.

 

[John Popelish]

"HARRY DELLAMANO" <harry_td@verizon.net> wrote in message news:<lCwqd.2588$wr6.2162@trnddc04>...

"John Popelish" <jpopelish@rica.net> wrote in message
news:41AA96A8.B03ABEF8@rica.net...
But that 1.5 factor is allowed for 5 seconds. I was assuming that
from an I^2*t fusing effect that the dissipation capability would go
up quite a bit if the time was in milliseconds.

A-huh, assuming.
Harry

Yep. A good data sheet is much better than an assumption:
http://www.irctt.com/pdf_files/HSF.pdf

--
John Popelish

 

[Active8]

On Mon, 29 Nov 2004 18:25:09 +0000, Guy Macon wrote:

David L. Jones wrote:

1/2/4/8 steps? that ain't all that useful and it isn't really
a "decade" box.

It's very useful indeed. The key is to understand binary math.

Lets say that you want a 3.65K resistor.
Set the 3 by turning on the 1 and the 2 on the 1000s decade,
set the 6 by turning on the 2 and the 4 on the 100s decade,
set the 5 by turning on the 1 and the 4 on the 10s decade.
For experienced engineers/technicians, this will come naturally.
For those just learning, the practice in binary to decimal
conversion teaches them something that they will use a lot.

Try that as a selling point?
--
Best Regards,
Mike

 

[Active8]

On 29 Nov 2004 13:01:09 -0500, Byron A Jeff wrote:

Lastly, back in figure 4-2, it states the 36 GPR in bank 1 are mapped
to bank 0. Does this mean they're connected, and if a GPR in bank X
changes, then the same GPR in the other bank will change also?

Yes.

If so, are any of the SPR connected in this fashion?

Some. For example the STATUS register is usually mapped into every bank.


Thanks for the patience if you've made it this far, and I really
appreciate the help!

No problem.

But I beg of you not to get caught with the 16C84 or 16F84. They are older
than dirt. The newer chips bring a lot to the table, and cost less than the
older chips. Take a read of my page for more info.

Then take the link to the glitchbuster page. It's an easy way to get
everything you need for a PIC project fast.
--
Best Regards,
Mike

 

[Guy Macon]

Arie de Muynck wrote:

At least in Europe, most telephone exchanges use a negative voltage
referenced to good old mother Earth.

Why negative? Is it some 'cathodic protection' in case a pinhole
leak occurred?

Don't think pinhole leak. You are assuming modern insulation.
Think cotton insulation that may get damp - that's all they had
when this stuff was invented.

If negative was grounded, the electroplating effect would
take copper away from the wires and plate it on the grounding
rods/stakes. With positive grounded, the electroplating effect
takes copper away from the grounding rods and plates it on the
wires. Grounding rods are made to be much thicker and easier
to replace.

Extra credit question: why do most electronics have negative
ground? Hint: think about the physics of vacuum tubes.

BTW, in the old manual switchboards, tip was chosen to be
positive/ground and ring to be negative/power because the
tip is more likely to contact some exterior grounded surface.

--
Guy Macon <http://www.guymacon.com>

 

[Fred Bloggs]

Sean Bartholomew wrote:

im building a circuit using the 4052 cmos chip.
i need to connect the 4052 Vee to at least as negative as -4V for
audio reasons. it cant be at 0 for my purposes.
i would like the unit to fit into the 9V supply format (widely used in
the guitar fx world) but ive pursuaded myself to go to a 12V supply as
i need a regulated +5V supply (not applicable with a +9V trans if i
intend to have -4V unless i get a REGULATED 9V
trans...hmmm....possible).

Well- if you have 9V regulated then you only need one standard
regulator. If Vee of the 4052 is your only load, then this current is
all leakage- you keep the 79L05 in regulation with a small 500uA current
through the 10K which guarantees the 5V loading always exceeds the -4V
current draw.
View in a fixed-width font such as Courier.

.
.
.
.
. + >-----+----------+-------+-----+-------+---(+)
. | | | | |
. 9V | | | | |
. | | |+ /
. - >-+ |+ | === 10K 5V Load
. | === |gnd |1u /
. | |1u +--+---+ | \ |
. | | in| |out| | |
. | +-------|79L05 |---+-----+-------+----+
. | | | | | |
. | | +------+ | ---
. | | | ///
. | |
. | | -4V Load
. | |
. | | |
. | | |
. +---+--------------------------------+---(-)
.
.
.

 

[Rich Grise]

On Sun, 28 Nov 2004 12:33:30 -0800, Scott Miller wrote:
....

I'm really trying to keep the cost and component count down to make it an
easy hobby project, but I'd also like it to not suck a battery dry in 2
hours. If anyone's got any suggestions on how to implement a better
regulator, or maybe a different supply design entirely, let me know.

Current schematic is at: http://n1vg.net/geiger/images/gc1-9v.png. The HV
supply is on the right-hand side - everything from MCU pin 13 to the
Geiger-Mueller tube. The pin header at left is for an LCD display.

I vote you don't need to regulate it at all. Find a very-high-impedance
meter and measure the voltage, then just adjust your pulse width so it's
500, and be done with it. A geiger tube doesn't take very much current at
all, even when it fires.

I'd also look at the transformer polarity, since it is kind of a flyback
design. I saw one very much like this in a NASA tech brief, which they
called a "forback" since it's kind of a morphodite of forward and flyback
converters.

Good Luck!
Rich

 

[Rich Grise]

On Mon, 29 Nov 2004 16:49:08 +0100, Frank Bemelman wrote:

....

I am not going to comply with any further spanish inquisition.

Best regards,
Frank Bemelman

Uh-oh! Looks like you got on somebody's list! I'd start watching my back.
Maybe put up a picture of Our Beloved Leader in your office or something
- you know, look loyal.

Good Luck!
Rich