Chip with simple program for Toy

[Day Vee]

On Sat, 12 Jul 2003 16:46:34 -0500, "Garrett Mace"
<g.ryan@macetech.com> wrote:

"Day Vee" <my_newsgroups@btinternet.com> wrote in message
news:jbt0hvo1c4m1ilhmqog3rr103dvgg1phid@4ax.com...
Try this:
Put your mobile/cell phone in an all metal biscuit/cookie tin/box.
Call it from another phone and it responds.
In theory this should not happen.
Whatever became of Micheal Faraday's "cage principle" ?

There's summat strange going on ...

Day Vee


Not really, for most people the phone won't in fact respond, unless (like
you) they have a cell tower on their roof.

Even if the cell tower were on my roof, I thaught a "Faraday cage"
composed of solid metal would stop ALL radiation, regardless of
strength.

 

[Day Vee]

On Sat, 12 Jul 2003 23:25:04 +0100, "Neil" <fredd133@hotmail.com>
wrote:

Is the tin earthed? or is it just acting like a bit of metal going up and
down in voltage (?) with the signal?

Please try the experiment.
Place a normal/regular mobile/cell phone in a sealable metal
biscuit/cookie tin.
The tin has no kind of earth strap or earth bonding, it can sit
anywhere, on a shelf, on a table.
I've done this experiment several times and the metal encased phone
still responds.
Yet, according to Faraday's cage principle, it shouldn't.
Wierd.

 

[Day Vee]

On Sat, 12 Jul 2003 23:25:04 +0100, "Neil" <fredd133@hotmail.com>
wrote:

Is the tin earthed? or is it just acting like a bit of metal going up and
down in voltage (?) with the signal?

I'll have to conduct this experiment with a properly earthed metal
box. I'll get back to you with the result.

 

[Bill Bowden]

Jonathan Kirwan <jkirwan@easystreet.com> wrote in message news:<9gg0hvc78aam281vo83rlnlj1299kud76b@4ax.com>...

On 12 Jul 2003 10:28:39 GMT, melaniegree64694@aol.com
(Melaniegree64694) wrote:

Does anyone have a circuit to drop 12V DC to 8V DC with an output of 3 Amps?

Hi, again.

This is just about taken from the data sheet for the LM317:

: ,-------------------c e-------,
: | Q2 \ / |
: | 2N3055 --- |
: | or MJE3055 | |
: | | R6 |
: +---------e c------+---/\/\---+
: | Q1 \ / 470 |
: | 2N2905 --- |
: | | |
: | / R4 |
: | \ 5K |
: | / |
: | R3 |inp,-------,out | 1N4002
: +12V or >---+-+---/\/\---+---| LM317 |---+----+--+------+-------+---> 8V
: more | 22 '-------' | | | |
: | adj| / --- | |
: | | \ R1 / \ D1 | |
: | | / 270 --- + | |
: --- C1 | | | --- C2 / R5
: --- 10uF +-------+---+---' --- 47uF \ 1500
: | | + | - | /
: | \ R2 --- C3 | |
: --- / 1500 --- 10uF | |
: gnd \ - | --- ---
: | | gnd gnd
: --- ---
: gnd gnd


I think the output voltage might be a tenth of a volt or so
above your desired 8V, but very close.

If you want to try something just a little bit easier, here's a
modified version without Q2 and R6:

: +---------e c-----------------,
: | Q1 \ / |
: | 2N2955 --- |
: | or | |
: | MJE2955 / R4 |
: | \ 10 |
: | / |
: | R3 |inp,-------,out | 1N4002
: +12V or >---+-+---/\/\---+---| LM317 |---+----+--+------+-------+---> 8V
: more | 1.5 '-------' | | | |
: | adj| / --- | |
: | | \ R1 / \ D1 | |
: | | / 270 --- + | |
: --- C1 | | | --- C2 / R5
: --- 10uF +-------+---+---' --- 47uF \ 1500
: | | + | - | /
: | \ R2 --- C3 | |
: --- / 1500 --- 10uF | |
: gnd \ - | --- ---
: | | gnd gnd
: --- ---
: gnd gnd


I think that should work okay, as well. You'll should use some
heat sinks on the 2N2955/2N3055/LM317 type parts, just to be
safe. The LM317 is some US$0.60 at Digikey. I don't know what
Farnell charges, but you can look there and see.

While I haven't built these to test them, I believe they may
work as specified. If it turns out that you need to support an
input voltage a little below 12V, you can adjust R3 to 1 ohm and
that will buy you back a few more tenths on the input side.

Jon

The LM338K adjustable voltage regulator is rated to 5 amps.
Just 2 resistors needed to set the output voltage.
Saves a lot of parts, but it's a little more expensive
at $5.68 from digikey. (TO-3 package).

-Bill

 

[Jonathan Kirwan]

On 12 Jul 2003 18:34:50 -0700, HoldenCaulfield@att.net (Bill
Bowden) wrote:

snip
The LM338K adjustable voltage regulator is rated to 5 amps.
Just 2 resistors needed to set the output voltage.
Saves a lot of parts, but it's a little more expensive
at $5.68 from digikey. (TO-3 package).

I think that's a good suggestion. Another example of this is
Linear Technology's LT1085, which is another 5A unit. But
again, the prices are kind of high at digikey. So I avoided
using it.

Jon

 

[tempus fugit]

Sorry, that should've been:

toccata@ciaccess.com

Thanks


"Kasper" <repzak@hotmail.com> wrote in message
news:3f07f654$0$5152$edfadb0f@dread11.news.tele.dk...

Hey

Tjeck elektor, i mean they have a schematic on a fine Cap meassure...
building with a pic and a display.. auto range and so on...

let me know if you are interastead, then i can mail you the article, i
mean
i still haved it

--
Mvh Kasper

Tjek Elektronik Chatten pĺ -> http://www.angelfire.com/alt/elektronik/
"tempus fugit" <tocatta.no.spam@ciaccess.com> skrev i en meddelelse
news:rwGNa.51417$hr3.27020@news.primus.ca...
Hey all;

I'm thinking of buying either an ESR meter or capacitance meter, but am
not
sure which is more useful. I would be using it mostly for
troubleshooting,
so I was thinking ESR meter, since it is my understanding that a cap is
more
likely to fail or cause problems because of high ESR rather than
incorrect
capacitance.

Any advice?

Thanks

 

[Spajky]

On Sat, 12 Jul 2003 11:07:31 -0700, "Baphomet"
<fandanospam@catskill.net> wrote:

Probably the easiest, although certainly not the most elegant, way would
be to put a 3.9volt zener diode between your 12 volt source and your desired
8 volt output.

better 5 normal diodes serially (have to be better higher than 5A
ones!)

-- Regards, SPAJKY
- http://freeweb.siol.net/jerman55/HP/Spajky.htm
Celly-III OC-ed,"Tualatin on BX-Slot1-MoBo!"
E-mail AntiSpam: remove ##

 

[Cees Keyer]

tempus fugit wrote:

Sorry, that should've been:

toccata@ciaccess.com

Thanks


"Kasper" <repzak@hotmail.com> wrote in message
news:3f07f654$0$5152$edfadb0f@dread11.news.tele.dk...

Hey

Tjeck elektor, i mean they have a schematic on a fine Cap meassure...
building with a pic and a display.. auto range and so on...

let me know if you are interastead, then i can mail you the article, i

mean

i still haved it

--
Mvh Kasper

Tjek Elektronik Chatten pĺ -> http://www.angelfire.com/alt/elektronik/
"tempus fugit" <tocatta.no.spam@ciaccess.com> skrev i en meddelelse
news:rwGNa.51417$hr3.27020@news.primus.ca...

Hey all;

I'm thinking of buying either an ESR meter or capacitance meter, but am

not

sure which is more useful. I would be using it mostly for

troubleshooting,

so I was thinking ESR meter, since it is my understanding that a cap is

more

likely to fail or cause problems because of high ESR rather than

incorrect

capacitance.

Any advice?

Thanks

In a recent magazine, elektuur sept 2002, a design for a ESR meter was
published.

I could scan the article and e-mail it to you if you want.
It's based on a 200 kHz oscilator and a four wire resistance measurement.
It will measure ESR in circuit so for repairing it's a "handy" design.
Probably you could read the text, for details.

Cees.

 

[John Jardine]

Gareth <gareth.harris@nobody.nowhere.invalid> wrote in message
news:Im1Qa.4747$SU1.119320@newsfep1-win.server.ntli.net...

Day Vee wrote:

Try this:
Put your mobile/cell phone in an all metal biscuit/cookie tin/box.
Call it from another phone and it responds.
In theory this should not happen.
Whatever became of Micheal Faraday's "cage principle" ?

There's summat strange going on ...

Day Vee

Only a perfect conductor will completely block all radiowaves. For a
non-perfect conductor the radiowave is attenuated exponentially as it
travels though the material. For most metals this attenuation is very
rapid and assuming that the signal is perfectly blocked is not far off.
However if you have a very thin bit of metal which is not a
particularly good conductor, and a strong enough signal to start with, a
detectable signal will get through.

I expect the cookie tin is made of very thin steel (steel not being a
particularly good conductor) so just enough signal gets through to make
the phone ring.

The skin depth of steel is about 0.05 mm at 1 GHz, so the signal will be
attenuated by a factor of:

e^(thickness/0.05)

so if your tin is 1/10 mm thick the signal will only be attenuated by

e^(0.1/0.05) = e^2 = 7.4

This is not a lot of attenuation and I am not surprised that a phone
could still work.

Try the experiment again with different metal containers. For example
if you have a good quality heavy saucepan with a metal lid try that.

Gareth.

PS I tried it and the signal was blocked.

-----------------------------------------------------------------------
To reply to me directly:

Replace the text after the@symbol with: totalise DOT co DOT uk

Good question. Neat answer!. Nice one!.

 

[Rich Grise]

Gareth <gareth.harris@nobody.nowhere.invalid> wrote in message news:<Im1Qa.4747$SU1.119320@newsfep1-win.server.ntli.net>...

Day Vee wrote:

Try this:
Put your mobile/cell phone in an all metal biscuit/cookie tin/box.
Call it from another phone and it responds.
In theory this should not happen.
Whatever became of Micheal Faraday's "cage principle" ?

There's summat strange going on ...

Day Vee

My WAG is that it's not a "poor shielding" issue, but that at the

freqs involved with a cell phone, the breadbox is probably acting
as an antenna, and reradiating inside itself. Are the freqs high
enough that you might have a cavity resonator?

Cheers!
Rich

Only a perfect conductor will completely block all radiowaves. For a
non-perfect conductor the radiowave is attenuated exponentially as it
travels though the material. For most metals this attenuation is very
rapid and assuming that the signal is perfectly blocked is not far off.
snip

 

[John Fields]

On Fri, 11 Jul 2003 18:27:51 -0700, baywood
<baywood@drizzle.invalid.com> wrote:

What I have been looking for is a circuit for a switch that operates
at a set relative humidity. Essentially I need a 5% RH range with one
fan turning on at the low end and another at the high end of the
range. I'll be working with 12VDC and the fans draw 130mA each. My
knowledge of electronics is pretty limited. It seems most RH sensors
are based on capacitance (e.g.
http://www.kollar.com/observatory/cloud2/691901.pdf) and I have no
idea of how to build a switch based on capacitance. Anything pointing
me in the right direction would be appreciated.

---
They're based on capacitance, but you can get them with a DC ouput
voltage which varies with relative humidity, so all you'd need would be
a couple of comparators to determine the fan setpoints. Check this out:

http://content.honeywell.com/sensing/prodinfo/humiditymoisture/
--
John Fields
Professional circuit designer
http://austininstruments.com

 

[Garrett Mace]

Not really, for most people the phone won't in fact respond, unless
(like
you) they have a cell tower on their roof.

Even if the cell tower were on my roof, I thaught a "Faraday cage"
composed of solid metal would stop ALL radiation, regardless of
strength.

It would be solid metal if you soldered or welded all the seams shut.
A cookie tin lid doesn't make a very good electrical contact to the
box. Really tight EMI shielded boxes have elaborate spring finger
stock or metallic gaskets around the seams. RF is sneaky stuff.

John

Plus half-a-mile is still pretty close for a cell tower (if it's not one of
those microcell towers you see in cities).

I used to live in a house with a thick foil moisture barrier. Essentially it
was a metal box, and made reception nearly impossible for anyone's cell
phone, until they installed a tower up on the ridge, line-of-sight visible
from the kitchen window. ;-)

If there's a gap in the shielding bigger than the wavelength you're trying
to block, you'll leak a bit. It does reduce the signal strength a bit. My
cell phone almost drops off the network when it's inside a metal shelf in my
cube at work; and that's open to RF on two sides.

Another experiment is to put the phone in the microwave and try calling it.
I'd do it but I don't have another phone. Plus there's always the risk of
turning the microwave on....

 

[Byron A Jeff]

In article <3zqQa.158$m53.25256@petpeeve.ziplink.net>,
<foobear@foobar.com> wrote:
-Hello folks,
-
-I'm trying to program a 16f84 PIC by Microchip with the PICALL Programmer.
-I'm using the PICALL Programmer Software as well v0.14

An aside: once you get rolling you'll definitely want to take a look at newer
members of the PIC family. They are much better and much cheaper than the
16F84. These include the 16F628 and the 16F819. Definitely worth checking out.

I've outlined some points in my 16F628 comparison page:

http://www.finitesite.com/d3jsys/16F628.html

-
-The programmer hardware and software _seems_ to work. I can read data
-off it (although there is no real data on these blank chips), and erase
-them without error. But when I try loading code on there or verifying
-it using the 'Verify' option with PICALL I get errors such as
-
-Verify Error
-Program: addres=0000 buffer=2810 device=3fff
-
-Would this indicate a problem with the code, or something else?

A problem with the programmer. the 3fff from the device indicates that nothing
has been programmed.

-
-I've tried some hex dumps off some pic sites and I also tried compiling
-simple code using gpasm under GNU/Linux and I tried the P84 compiler by
-Charles Manning that came bundled with a DIY programmer kit 117

Not relevant in this case. It's the programmer/programmer software/hardware
interface, not the code.

-
-Does anyone have any simple 16f84 code I could try using to test out this
-programmer? (in hex if possible) or maybe some hints as to what I should try

I general I find the keys are doublechecking the pin assignments on Tait style
programmers. However I'm not sure how the PICALL is laid out.

-
-If this is off topic here, I apologize.

This is as good a place as any. There's a lot of discussion of PICs in
comp.arch.embedded. Also the PICLIST is an invaluable resource. You can
get started at http://www.piclist.com. Finally since you using Linux then
the resources at my TLVP site (linked from the 16F628 page above) and the
gnupic project, which has gpasm, are also useful.

-Thanks

No problem. Good Luck.

BAJ

 

[Joel Kolstad]

Day Vee <my_newsgroups@btinternet.com> wrote:

Even if the cell tower were on my roof, I thaught a "Faraday cage"
composed of solid metal would stop ALL radiation, regardless of
strength.

If your Farady cage provides 100% coverage (i.e., the seams are properly
finished) AND THE METAL IS A PERFECT CONDUCTOR, you shouldn't be able to
produce any _time-varying_ field inside the Faraday cage based on what you
do outside.

A regular biscuit tin is perhaps a far enough cry from a perfect conductor
that its skin depth at 900MHz (old analog cell phone system) is on the order
of the thickness of the walls and therefore you'll simply have an attenuated
signal. Likewise, if one of the long seams isn't particularly well selled,
it may allow enough radiation inside to activate the phone.

Note that -- in general -- Faraday cages do not prevent static fields from
'escaping.'

---Joel Kolstad

 

[Joel Kolstad]

Rich Grise <richardgrise@yahoo.com> wrote:

My WAG is that it's not a "poor shielding" issue, but that at the
freqs involved with a cell phone, the breadbox is probably acting
as an antenna, and reradiating inside itself.

This won't happen if the box is a perfect conductor. Currents will be
induced on the _outside_ of the box (and if the box does have the proper
dimensions to become resonant, the currents could become quite large), but
their ability to penetrate to the inside of the box is a function of the
box's conductivity: Perfect conductors allow no penetration. Finite
conductors, such as a real tin box... well, yes, you could end up with some
currents on the inside of the box, getting us back to the tin's model as an
imperfect attenuator.

---Joel Kolstad

 

[A E]

happyhobit wrote:

Hi All,

Is there any reason I can't use a 'Fixed' 5 volt regulator and a voltage
divider to create an "Adjustable Regulator' for 5 VDC to (Vin-VDO)?

Jay

Well, I don't know what you mean exactly, but it's generally a bad idea to use a
voltage divider as a regulator. It wastes a lot of power, and doesn't regulate.
Perhaps if you drew a schematic for what you have in mind, all I can see is
you're trying to get a range of voltages from 5V to (vin-VDO), which means you'd
be putting a divider (pot?) between the regulator's input and output pins?
Look into regulators that are adjustable from the factory, like the venerable
LM317 series.
Maybe you can calculate for yourself why a divider is not a regulator, and why
it wastes power.

 

[John Jardine]

kash <yahoo.com> wrote in message news:beutq701h68@enews2.newsguy.com...

Hello all,
I have found a circuit for a sound level meter here
http://hop.concord.org/s1/ext/s1em.html
My questions:
1. How good is it, should I try to build it?
2. What type of microphone is the input, and could I use
an electret type directly as shown in the diagram?
Tia

It's a straightforward X1000 ac amp, with added rectifier and would work
OK.
The mike looks to be one of the cheap, standard electret types. As they all
seem to make us of a 1k resistor to a 9v supply then you shouldn't have a
problem.
The 741 op-amp is a bit long-in-the-tooth but perfectly OK.
regards
john

 

John Jardine <john@jjdesigns.fsnet.co.uk> wrote:

foobear@foobar.com> wrote in message
news:3zqQa.158$m53.25256@petpeeve.ziplink.net...
Hello folks,

I'm trying to program a 16f84 PIC by Microchip with the PICALL Programmer.
I'm using the PICALL Programmer Software as well v0.14

The programmer hardware and software _seems_ to work. I can read data
off it (although there is no real data on these blank chips), and erase
them without error. But when I try loading code on there or verifying
it using the 'Verify' option with PICALL I get errors such as

Verify Error
Program: addres=0000 buffer=2810 device=3fff

Would this indicate a problem with the code, or something else?

I've tried some hex dumps off some pic sites and I also tried compiling
simple code using gpasm under GNU/Linux and I tried the P84 compiler by
Charles Manning that came bundled with a DIY programmer kit 117

Does anyone have any simple 16f84 code I could try using to test out this
programmer? (in hex if possible) or maybe some hints as to what I should
try

If this is off topic here, I apologize.
Thanks
-v

Don't know if this helps but it looks like your progger is not working right
and if it's the same progger I have then ...
You need 15V to 25V to get the programmer working. It won't do things until
the Green led is lit. The wall wart that is no doubt powering it, should be
switched to the "12v" position.(polarity doesn't matter). Also the 2 Red
leds would be ON if the printer cable is not plugged in correctly.
regards
john

Hello,

I'm actually feeding 18v. The green LED comes on, anad one of the red
ones as well. The interesting thing is I get the same type of errors
with the PICALL programmer, and P16PRO programmer (kit 81v4).

I've also tried 2 different 16f84 chips. The self tests and the cable
tests run ok. and the 'Erase' and 'Read' functions work ok. If I have
no code in the PICALL software buffer (program memory all reads 3fff)
'Verify' and 'Program' work but as soon as I load some code in the
PICALL software buffer and the Verify or Program I get those errors.

I thought I built my first programmer (kit81) wrong. so I got the PICALL
programmer and the same errors occur


P.S What would happen if the fuses for code protection were blown on these
chips?




-v

 

[Gary Lecomte]

"kash" <yahoo.com> wrote in message news:<beutq701h68@enews2.newsguy.com>...

Hello all,
I have found a circuit for a sound level meter here
http://hop.concord.org/s1/ext/s1em.html
My questions:
1. How good is it, should I try to build it?
2. What type of microphone is the input, and could I use
an electret type directly as shown in the diagram?
Tia

It will work, but its not too practical for practical audio
measurements. A good meter will have "weighted scales" to compensate
for the hearing of our ears.

Take care......Gary

 

[Bill Bowden]

"kash" <yahoo.com> wrote in message news:<beutq701h68@enews2.newsguy.com>...

Hello all,
I have found a circuit for a sound level meter here
http://hop.concord.org/s1/ext/s1em.html
My questions:
1. How good is it, should I try to build it?
2. What type of microphone is the input, and could I use
an electret type directly as shown in the diagram?
Tia

The 1K resistor on the mic looks a little low.
You will probably get more signal from the mic
with a 10-20k resistor. The mic sees a 1K load
in parallel with a 10K which is less than 1K total.
If you use 10K, the mic will see a 5K load and
the output voltage will be higher.

-Bill