On Tuesday 30 March 2004 06:29 pm, Glenn wrote:

Dear Group:

This may be a stupid suggestion, but what if one were to install
optoisloators on the cable line? This would short-circuit (literally and
figuratively)what the cable company can detect? Or is there something I
have not thought of?

Install them how?

A typical opto will require at least several millamps of current to make the
input side of it do anything useful -- that's DC.

A typical cable is carrying a bunch of different RF signals, all at very low
levels, way too low to do anything useful with an optoisolator.

Alien Steve

The flyback has a ferrite core going down the middle of the windings
and extending outside to form a large 0. This large 0 is made with a
split which is held together by a large U shaped spring clamp. Is the
external portion where to wrap these new primary windings around?

The crack (from falling form the workbench) is the ferrite and is all
the way through. The large U clamp keeps it still in one piece. Do
do think it would be ruined?

Bob

--- In Electronics_101@..., "Steve" <alienrelics@y...>
wrote:

--- In Electronics_101@..., "rsnyder187"

<rsnyder187@y...>

wrote:

I have seen several circuits as you have described. I plan to

try

and open up the plastic flyback housing and see if it is possible

to

add some primary windings easily.

No! Do not damage the housing. There is nothing you can do inside
there except break the insulation and wire. The secondary is on the
outside layer.

Put the extra winding on the ferrite core. These extra primary
windings are usually added on the core opposite from the current

windings.

BTW, did you say you dropped it and cracked the ferrite? If so, it's
ruined if there is much of a chunk missing. You may get some use

from

it, but I would not count on too much.

If it is a minor chip, don't worry about it.

Keep in mind that you are talking about generating lethal voltages
which can jump several inches through air, or travel -much- greater
distances along something as innocuous as a chunk of wood.

Alien Steve

Dear Group:

This may be a stupid suggestion, but what if one were to install optoisloators on the cable line? This would short-circuit (literally and figuratively)what the cable company can detect? Or is there something I have not thought of?

Glenn

Electronics_101@... wrote:

Message: 5
Date: Mon, 29 Mar 2004 00:51:53 +0100 (BST)
From: signal snatcher <signalsnatcher@...>
Subject: Re: Re: what can the cable company detect?

Phone companies use a technique called "Time Domain Reflectometry (TDR)" which is a type of radar. It can be used on any type of cable and optical fibre. Its very accurate, down to a centimetre or so. It can tell if the line has taps, bridges, extensions and what type of load is at the other end.

It s comparatively easy to make up a TDR; Google should have any number of sites. You do need a CRO though and a lot of practice.

If you are checking any type of cable TDR is the way to go, so I imagine that's what cable TV companies use. In Australia the phone companies run cable and broadband and phone companies have seen _everything_ in the way of illegal use and faults, so you can't put much over them. On the other hand every phone company seems to have the attitude that customers are either thieves or idiots so they never take your explanantion for anything.

Dave Mucha <dave_mucha@...> wrote:
--- In Electronics_101@..., Albert van Mil wrote:

I had a problem years ago with the phone. We were billed 10 times
as high as usual, so something went awry. Asking the phone company,
they told they could detect how many phones were connected in our
house and they just said they detected only one and no further

problems.

We wanted an investigation so they came... It turned out someone cut
our phonecable and put his phone on it, outside the flat, and had

lots of

expensive calls. Later on he just soldered (PbSn) a piece of cable

to cross

the cut to establish the connection again. We didn't have to pay

the bill

Conclusion: they can't detect what's happening, although they say

so.

They can
do so if there is a nice homogeneous cable but not anymore if there

are

connectors (with their resistance), soldered cables, wires mounted

by

screws etc.
Albert

I had a problem years abgo (before digital cable) with the phone company. The told me they wanted to run a diagnostic and then in less than a minute, told me the problem was something like 3,127 feet and 11 inches away from the central office. the next day the repair truck came out and stopped just around the corner, put up a ladder and found the problem. Since she said I was something like 3,321 feet and 7 inches from the central office, they knew exactly where to look.

But our Church had gotten some huge calls and teh phone company couldn't find anything. One of our guys went out to the phone box and found it was loose. Then kept an eye out and a few nights later found a guy using alagator clips to tap into our phones.

Guess they have some idea what is going on.

Dave









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--- In Electronics_101@..., "Davin" <dy9213@r...> wrote:

Hi all,
I've got this capacitor with a rating of 5200uf and 64WV. What

does WV

means? wave volts? But how does this converts to Volts.

Thanks,

Davin

Working Voltage

Hi all,
I've got this capacitor with a rating of 5200uf and 64WV. What does WV
means? wave volts? But how does this converts to Volts.

Thanks,

Davin

开云体育

开云体育

开云体育

--- In Electronics_101@..., "rsnyder187" <rsnyder187@y...>
wrote:

I have seen several circuits as you have described. I plan to try
and open up the plastic flyback housing and see if it is possible to
add some primary windings easily.

No! Do not damage the housing. There is nothing you can do inside
there except break the insulation and wire. The secondary is on the
outside layer.

Put the extra winding on the ferrite core. These extra primary
windings are usually added on the core opposite from the current windings.

BTW, did you say you dropped it and cracked the ferrite? If so, it's
ruined if there is much of a chunk missing. You may get some use from
it, but I would not count on too much.

If it is a minor chip, don't worry about it.

Keep in mind that you are talking about generating lethal voltages
which can jump several inches through air, or travel -much- greater
distances along something as innocuous as a chunk of wood.

Alien Steve

I have seen several circuits as you have described. I plan to try
and open up the plastic flyback housing and see if it is possible to
add some primary windings easily.

The horz circuit from the original board was too complicated for me
to figure out an easy way of removing it. So the adding windings and
making an oscilator circuit may be a more practical solution.

I may pick up another monitor (to remove the flyback and be more
careful no to not damage it) and also look at an old microwave oven.



--- In Electronics_101@..., "manifold" <manifold_1@y...>
wrote:

--- In Electronics_101@..., "rsnyder187"

<rsnyder187@y...>

wrote:

I picked up an old 14" monitor at Goodwill for $2.00. It

worked. I

removed the flyback transformer for HV experimentation.

I hooked up a 9 volt battery on the input and setup a small gap
between the HV output and hv return. I though a momentary 9v

pulse

would produce an observeable spark on the output. No such luck.

Any suggests?

Bob

I am not a TV repair expert, but the flyback transformer may be
powered from a higher voltage supply. 9v may be producing a few
thousand volts but not enough to make a spark. You need around 10kV

to

see a good spark.

Other things I remember about flyback transformers:
They are very low output power.
They are self resonant so they are not just a simple transformer.
The circuits for creating your HV supplies using old flyback
transformers always start by winding a new primary and do not use

the

primary on the coil.

Try searching the web for high voltage and flyback. There are a lot

of

circuits out there that people have built.

For what? A 555 to measure level, or using a 3915 as a VU meter?

Alien Steve

--- In Electronics_101@..., slamet suharjo
<slametsuharjo@y...> wrote:

Hello,
any idea for this!

J-P <jpsch@h...> wrote:
Thanks,
I am looking around as we speak he he or write!
J-P

--- In Electronics_101@..., "manifold" <manifold_1@y...>
wrote:

I think radio Shack still carries the LM3915 bar/dot display driver.

I have build a few of these circuits on perf board and it is not hard.
The hard part is mounting the LEDs like you want them.


Also, use google and search for bar/dot display, lm3915, lm3914,
lm3916. Many people have simple circuits on the web using these parts.

Thanks,
I am looking around as we speak he he? or write!
J-P

--- In Electronics_101@..., "manifold"
wrote:
> I think radio Shack still carries the LM3915 bar/dot display driver.
>
> I have build a few of these circuits on perf board and it is not hard.
> The hard part is mounting the LEDs like you want them.
>
>
> Also, use google and search for bar/dot display, lm3915, lm3914,
> lm3916. Many people have simple circuits on the web using these parts.

---

Do you Yahoo!?
- File online. File on time.

I settled on using a DSC PIR. Available locally for a reasonable
price. Eagle Eye is cool but this would be a permanent installation,
battery powered wouldn't be suitable.

One nice thing about the DSC, it has a jumper for "Hostile"
environment. Tones down the sensitivity quite a bit, perfect for my
needs!

--- In Electronics_101@..., Neil <cobra_neil@a...> wrote:

Hi,

Lurker here. Missed a lot of this thread, but it sounds like

you're looking

for a motion sensor which operates on low-voltage. If so, check

out the X10

motion sensors (called Eagle Eye or something IIRC) ... they're

very low cost

$5-$10 each, and are powered by a couple AAA cells. They even

include a

transmitter.

Cheers,
-Neil.

I cut the vinyl on my sign cutter. Despite having no holes, it does
not use SMT parts. Instead it uses standard DIP ICs and through hole
parts, but with the leads trimmed almost flush and surface soldered to
the board.

It is a very thin double-sided board, the back is used as just a
ground sheilding layer and is etched away behind part of the circuit
to reduce capacitive loading on a section with RF in it.

Etched using ferric chloride, not because I like FeCl but because I
got about 8 pounds of it very inexpensively. A friend of mine bought a
55 gallon drum full of 1 pound bags of dry FeCl, and then found out
that he could not mail acids without some special license.

I scanned it and the partly weeded vinyl and uploaded it to both
Homebrew_PCBs and NWPropmasters lists.

Steve

Thanks,
I am looking around as we speak he he or write!
J-P

--- In Electronics_101@..., "manifold" <manifold_1@y...>
wrote:

I think radio Shack still carries the LM3915 bar/dot display driver.

I have build a few of these circuits on perf board and it is not hard.
The hard part is mounting the LEDs like you want them.


Also, use google and search for bar/dot display, lm3915, lm3914,
lm3916. Many people have simple circuits on the web using these parts.

If you know what the primary side is (the one for the
120ac) you just can hook it up and measure the secondary.
But it is safer to test with low voltage.

Normally one uses another transformer or a variac to get, say 12V AC
and then you measure the other voltages. at no load the turn ratio
(primary voltage / sec. votage) is the same so if you get, say 2V at
the secondary you will get 20V when you operate it at mains voltage.

This is done because if you mess up with the wires, and accidently
hook the secondary (which is for low voltage) at mains you get a huge
voltage at the primary (now secondary) which may kill the transformer
or meter, or operator (not in the order of importance ;-) ).


so now you know the turn ratio, next is to measure the max. power
dissipation. this can be done by "guessing" from size, where i can't
help because my head operates with 50Hz and it is said your
transformers are a bit smaller, the second option is to measure the
internal resistance which is slightly more complicated, then with the
size you can determine which power it can dissipate and you get what
you can draw from it..

Most simple:
If the turn ratio is what you need just hook it up to the load you
have and if it does not get too warm it is ok to use.
Most have a thermal fuse built in.


I would have a good link on measuring transformer parameters, but it
is german and may not help you.

ask if you still have questions.

(and keep in mind mains voltage IS dangerous)

ST

--- In Electronics_101@..., "Davin" <dy9213@r...> wrote:

Hi all,

I'm have a small transformer on hand but I have no information about

it. Is

there any way to find the voltage output, Amp. output from the it?

All I

know is the primary is a 120ac designed to plug into the wall and

the

secondary is designed for a small radio. I believe it is a step

down.

What I'm actually looking for is a 120ac primary to 12v secondary at

1

ampere.

Thanks in advance,

Davin

Hi,

Lurker here. Missed a lot of this thread, but it sounds like you're looking
for a motion sensor which operates on low-voltage. If so, check out the X10
motion sensors (called Eagle Eye or something IIRC) ... they're very low cost
$5-$10 each, and are powered by a couple AAA cells. They even include a
transmitter.

Cheers,
-Neil.


On Thursday 25 March 2004 08:55 pm, ghidera2000 scribbled:

There are places for that kind of stuff, I'd rather this list stay
clear of genital shocking stuff.

Alien Steve

--- In Electronics_101@..., srinivas rao <ksrao_iete@y...>
wrote:

can any body send me a link for constructing a circuit whick gives

the electric shock but should be safe and it is just for the joy.

can anybody tell me how much is the normal safe current or voltage

to get the electric shock?

hoping best solutions and links

--- In Electronics_101@..., Albert van Mil
wrote:
> I had a problem years ago with the phone. We were billed 10 times
> as high as usual, so something went awry. Asking the phone company,
> they told they could detect how many phones were connected in our
> house and they just said they detected only one and no further
problems.
> We wanted an investigation so they came... It turned out someone cut
> our phonecable and put his phone on it, outside the flat, and had
lots of
> expensive calls. Later on he just soldered (PbSn) a piece of cable
to cross
> the cut to establish the connection again. We didn't have to pay
the bill :)
>
> Conclusion: they can't detect what's happening, although they say
so.
> They can
> do so if there is a nice homogeneous cable but not anymore if there
are
> connectors (with their resistance), soldered cables, wires mounted
by
> screws etc.
>
> Albert


I had a problem years abgo (before digital cable) with the phone
company. The told me they wanted to run a diagnostic and then in
less than a minute, told me the problem was something like 3,127 feet
and 11 inches away from the central office. the next day the repair
truck came out and stopped just around the corner, put up a ladder
and found the problem. Since she said I was something like 3,321
feet and 7 inches from the central office, they knew exactly where to
look.

But our Church had gotten some huge calls and teh phone company
couldn't find anything. One of our guys went out to the phone box
and found it was loose. Then kept an eye out and a few nights later
found a guy using alagator clips to tap into our phones.

Guess they have some idea what is going on.

Dave





>
>
> Matt wrote:
>
> >I was just wondering, what kinds of things can the cable company
> >detect on their lines? I know they can't detect how many tv's are
> >connected, cuz many many people only pay for 1 tv and have 2 or
more.
> >and satelite can't detect illegal connections either, cuz I know
> >someone who does it. so what CAN they detect? I'm sure they can
> >detect if a cable modem's connected, cuz it would have an ip then.
I
> >noticed some kind of an adapter on the line coming in. there's a
> >thick cable coming underground to the house, then it splits off to
4
> >normal sized cabled, each one with some kind of adapter on it.
they
> >look kinda like the isolators they sell at radio shack except a
> >little longer. could it be possible they fit a circuit into those
> >that they can send a signal to to change what channels people can
get?
> >
> >I'm just interested about it cuz I'm getting cable internet soon
and
> >wonder how it all works. they put the main connection for it right
> >across the road. from looking at the meter, it uses more power
them
> >my house, unless the scale on it's a lot lower. I heard there's a
way
> >to hack the modem to take the bandwidth limit off. is this true? I
> >don't really need that unlimited speed, cuz I'm pretty sure it's
at
> >least 1.5MB/s already anyway.
> >
> >
> >
> >
> >Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >



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Dave,

I pulled the flyback from the board. It dropped it from my workbench
when my cat jumped up. I just noticed the magnetic core is now
cracked. Good thing it was only $2.00.

The reason I didn't use the Horz circuit was that I was just trying
to experiment with a different supply.


Bob


--- In Electronics_101@..., "David Balma" <balma.d@c...>
wrote:

Bob,

Use the Horz driver circuitry that was in the original monitor as

its tuned

to the correct freq. The transformer works best at that freq and

will have

the proper driving signal. Caution though as these devices are not

toys by

any means. I used to work on TVs and have the most respect for these
circuits. There is the smell of corona and there is the smell of

burned

flesh.
A jacobs ladder is always fun to experiment. I would recommend

reading the

caution posted on the inside of the monitor when it comes to

working with

these voltages.

Dave

I picked up an old 14" monitor at Goodwill for $2.00. It

worked. I

removed the flyback transformer for HV experimentation.

I hooked up a 9 volt battery on the input and setup a small gap
between the HV output and hv return. I though a momentary 9v

pulse

would produce an observeable spark on the output. No such luck.

Any suggests?

Bob