magnetic field

[Watson A.Name - \"Watt Su]

"Rich Grise" <richgrise@example.net> wrote in message
newsan.2005.01.03.03.14.21.970684@example.net...

On Sun, 02 Jan 2005 16:13:17 -0800, Watson A.Name - "Watt Sun, the
Dark Remover" wrote:

[snip]

I just got thru with the following updated schem. This is where
it's at
as of Sunday afternoon Dec 03,05. Right now, the thing will bounce
a
cycle and a half and that's it, it's damped.

If I was gonna make things weird, I think I'd try the four sections
before that, I think that's my next step, 'cause I'm getting
nowhere
with this one.


Lose the 4.3 Megs to ground, and the 100 uF coupling cap, and replace
the 100 uF with another 330K R, and use a MOSFET:

I thought about using a 2N7000, but I wanted to 'play' with the bag of
JFETs that I got. I remember back in the mid '60s a friend and I built
a 'compander' that used lamps and photocells and some FETs. It didn't
work, and I had to go thru and adjust all the values of the bias
resistors to get the FETs to be in their linear region. It was all
because of the wide variation in JFETs' Vgs, which in the case of the
MPF102 can be anywhere from a half volt to 7.5V. That's a 15:1
variation!

I finally got the damn thing to sustain oscillations. See schem below.

+9V
|
.-.
| |
19k| |
'-'
|
.------------------------------------o
| | -Appx 4VDC
| |
.-. |
| | |
| | 330k +------o V
out
'-' |
| |
| |-
o---/\/\---o---/\/\----o---/\/\---|| MOSFET 2N7000
| | | |-
| 330k | 330k | 330K |
| | | o----.
| | | | |
| | | .-. |
--- 1.0u --- 1.0u --- 1.0u | | | +
--- --- --- 3.3k| | --- 2 caps
| | | See '-' --- 3200uF
| | | note | | total
=== === === below === ===
GND GND GND GND GND


Cheers!
Rich

I finally got this version to oscillate with the values below.

+9V
|
.-.
| |
33k| |
'-'
|
.----------------------------------------------o
| |
| o-------o |
.-. | | |
| | | 4.3M .-. |
| | 330k === | | +------o V out
'-' GND | | |
| '-' |
| +|| | |-
o---/\/\---o---/\/\--o--/\/\----o---||--o--->| JFET MPF102
| | | | || |-
| 330k | 330k | 330k | 10u |
| | | | o----.
| | | | | |
| | | | .-. |
--- 1.0u --- 1.0u --- 1.0u --- 1.0u | | | +
--- --- --- --- 3.3k| | --- 2 caps
| | | | See '-' --- 3200uF
| | | | note | | total
=== === === === below === ===
GND GND GND GNF GND GND

Note: 2 BAV21 diodes are in series with the 3.3k to give another 1.2V
drop, to
put more negative bias on the gate. Total drop across both is about
1.45V.

 

[Nicholas O. Lindan]

<nooneinparticular314159@yahoo.com> wrote

VHS reception ... poor or terrible. I can't find a good antenna
position [using rabbit ears] ... What can I get to replace this
that will solve this problem?

A large, very directional antenna mounted to a mast (or the chimney)
with an electric rotator.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/

 

[Tim Williams]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:10thucj1gduf480@corp.supernews.com...

It was all
because of the wide variation in JFETs' Vgs, which in the case of the
MPF102 can be anywhere from a half volt to 7.5V. That's a 15:1
variation!

T00bz r t3h pwn ;D

Tim

--
"I've got more trophies than Wayne Gretsky and the Pope combined!"
- Homer Simpson
Website @ http://webpages.charter.net/dawill/tmoranwms

 

[Watson A.Name - \"Watt Su]

"Tim Williams" <tmoranwms@charter.net> wrote in message
news:fn8Cd.48214$9E2.44191@fe06.lga...

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com
wrote
in message news:10thucj1gduf480@corp.supernews.com...
It was all
because of the wide variation in JFETs' Vgs, which in the case of
the
MPF102 can be anywhere from a half volt to 7.5V. That's a 15:1
variation!

T00bz r t3h pwn ;D

Tim

--

Eh?

 

[Nicholas O. Lindan]

<kamakize@gmail.com> wrote

Trying to
find out what it is. Http://www.randompostcinema.com/what.html

Lightmeter? Bridge circuit, provisions for an external mirror galvo,
battery.

Doesn't it have a nameplate? Pics are pretty fuzzy and it is
hard to read the legends. Try placing the thing upside down
on a scanner.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/

 

[Tim Williams]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:10tii85h5st2oa5@corp.supernews.com...

T00bz r t3h pwn ;D

Eh?

Ask Gregg t3h g33k.

http://en.wikipedia.org/wiki/Leet

Tim

--
"I've got more trophies than Wayne Gretsky and the Pope combined!"
- Homer Simpson
Website @ http://webpages.charter.net/dawill/tmoranwms

 

[CWatters]

<nooneinparticular314159@yahoo.com> wrote in message
news:1104719289.791502.171590@f14g2000cwb.googlegroups.com...

I am currently using a
Radio Shack amplified antenna with two telescoping antennae,

Get a proper roof mounted aerial. It should look something like this....

http://www.abcaz.com/5_1160279/aerials-boosters-and-splitters/masterplug-gold-52-element-tv-aerial.html

 

[CWatters]

"CWatters" <colin.watters@pandoraBOX.be> wrote in message
news:tFgCd.18804$u_.1514638@phobos.telenet-ops.be...

nooneinparticular314159@yahoo.com> wrote in message
news:1104719289.791502.171590@f14g2000cwb.googlegroups.com...
I am currently using a
Radio Shack amplified antenna with two telescoping antennae,

Get a proper roof mounted aerial. It should look something like this....


http://www.abcaz.com/5_1160279/aerials-boosters-and-splitters/masterplug-gold-52-element-tv-aerial.html

or this

http://www.screwfix.com/app/sfd/cat/pro.jsp?id=11094

 

[CWatters]

<nooneinparticular314159@yahoo.com> wrote in message
news:1104787856.310883.276250@z14g2000cwz.googlegroups.com...

In other words, anything I do needs to be inside my own apt, and should
not be very expensive.

Ok just use one of those big roof aerials indoors. You can get some quite
cheap models.

Ł9...

http://www.screwfix.com/app/sfd/cat/pro.jsp?id=11094

 

[The Phantom]

On Tue, 4 Jan 2005 05:56:29 -0800, "Watson A.Name - \"Watt Sun, the Dark Remover\""
<NOSPAM@dslextreme.com> wrote:

....snip

Mine is blinking away merrily. I put an EF on it and a blue LED, so I
can watch it doing its thing. On another BJT one I made, I put an amp
on one of the other phases, so I get this 'one-two..' flip-flop type of
flashing from the LEDs.


Just for grins, why don't you measure the amplitude on the gate (with at least a

10-to-1 probe, and on the drain and tell us what the actual stage gain is?

 

[john jardine]

"Nicholas O. Lindan" <see@sig.com> wrote in message
news:RBeCd.24$vP1.16@newsread3.news.atl.earthlink.net...

kamakize@gmail.com> wrote

Trying to
find out what it is. Http://www.randompostcinema.com/what.html

Lightmeter? Bridge circuit, provisions for an external mirror galvo,
battery.

Doesn't it have a nameplate? Pics are pretty fuzzy and it is
hard to read the legends. Try placing the thing upside down
on a scanner.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/

The 2 knobs fitted on it are UK military, circa 1939-1947. Maybe some
lend-lease item?.

 

[CWatters]

<kurtsutherland@comcast.net> wrote in message
news:1104901239.606342.111930@z14g2000cwz.googlegroups.com...

I am looking for a miniature trigger to release a small compression or
torsional spring that as about 1 lbf of force at full compression.

Take a look at an "aerotow release mechanisim" as used on full size or
model gliders. Might give some ideas. These are designed to release the tow
line while it's under tension.

http://www.flairproducts.co.uk/Accessories/Tow_release.htm

 

[Dave Garnett]

<kurtsutherland@comcast.net> wrote in message
news:1104901239.606342.111930@z14g2000cwz.googlegroups.com...

I am looking for a miniature trigger to release a small compression or
torsional spring that as about 1 lbf of force at full compression. The
trigger should fit in a space about 3X3X3mm or less. I have briefly
looked into nitinol wire, voice coils, watch mechanisms, and solenoids,
but haven't found anything small enough.

I am interested in any information that may direct me toward existing
products or classes of actuators/triggers that may be relevant.
Thank you,

Kurt Sutherland

You can get a lot of force when wax melts in a confined space - all sorts of
thermostats use this principle, for instance.



Posted Via Nuthinbutnews.Com Premium Usenet Newsgroup Services
----------------------------------------------------------
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[John Popelish]

"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:

"Rich Grise" <richgrise@example.net> wrote in message
newsan.2005.01.04.01.14.48.972750@example.net...

And if I had this puppy on my breadboard, another thing I'd have tried
if
I'd been at the same point yesterday would be the stepped impedances
in
the network that John Popelish was kind enough to offer.

Almost every PSO I've seen uses equal values. Nothing wrong with the
stepped values, tho. Except I would have had to change them. Am I
lazy? I guess so. )

The main reason equal capacitors are used is to allow the frequency to
be controlled by a ganged multi section variable capacitor. If fixed
frequency operation is all you are trying to achieve, the stepped
impedances can give you a lot more effective loop gain to support the
oscillation. The two to one steps I mentioned give you almost twice
the loop gain (the transistor has to provide only half the voltage
gain to make the thing oscillate).

--
John Popelish

 

[Frank Adam]

On Thu, 06 Jan 2005 13:25:22 GMT, boba3@earthlink.net wrote:

NL 60T8-B

Can some one please tell me:

A) What type of lamp this is? -and-

Something like this ?

http://tinyurl.com/4ydfg

B) Where can I obtain a replacement?

Any electronics warehouse should stock those. If the size is not the

same it won't be a big issue. Just place the light centered to where
the old one was.
Note the above requires an inline resistor to use at 240V and is an
orangish colour, but i'm sure the sales guys can help you there with
other types and the specs.
At that price you can even afford to blow a few.

--

Regards, Frank

 

[CWatters]

<tine.lassen@gmail.com> wrote in message
news:1105043441.940695.115770@f14g2000cwb.googlegroups.com...

I am looking for a digital to anagogue converter which can be used on
the road with my computer. I frequently come to hotels where the
telephone systems are digitalized. On the other hand a lot of them have
no LAN facility, so one is referred to use the telephone line and a
modem to check mail with the computer.
however, as long as the lines are digital, the inteface from the
computer to the telephone system is non-compatable, unless one uses a
box that converts digital signals to analogue signals. With such a box,
the modem may work and connection be established readily.

I have asked a dealer in Denmark who says that there is no such
all-purpose DAC box that one may carry in the gear for computer
accessories, because each digitalized phone system have its own more or
less dedicated converter box. And the wish to even find something
compact, light weight and flexible is out of the question.

So, does anyone know about an all-purpose, light weight DAC box that
may be used so as to ensure compatability between digitalized phone
systems (like in hotels) and the PC modem interface.
John Heilbrunn
heilbrunn[insert_at_sign]mail.dk

 

[CWatters]

Sorry I hit wrong button.

 

[Jerry G.]

I love your answer!!!

Jerry G.
======

 

[CWatters]

"CWatters" <colin.watters@pandoraBOX.be> wrote in message
news:k6iDd.22172$sJ5.1599584@phobos.telenet-ops.be...

I think you are probably looking for something called a "PBX adapter" or a
"Digital Line Converter"

http://www.laptoptravel.com/ProductList.aspx?ID=1537

http://www.ositech.com/Products/5os.htm

This article might help explain things...

http://www.laptoptravel.com/Article.aspx?ID=223

 

[Watson A.Name - \"Watt Su]

"Chuck Harris" <cf-NO-SPAM-harris@erols.com> wrote in message
news:JYKdna75LcTGH0TcRVn-uA@rcn.net...

Watson A.Name - "Watt Sun, the Dark Remover" wrote:

+9V
|
.-.
| |
33k| |
'-'
|
.----------------------------------------------o----o
| |
| o-------o |
.-. | | |
| | | 4.3M .-. |
| | 330k === | | +------o V
out
'-' GND | | |
| '-' |
| +|| | |-
o---/\/\---o---/\/\--o--/\/\----o---||--o--->| JFET MPF102
| | | | || |-
| 330k | 330k | 330k | 10u |
| | | | o----.
| | | | | |
| | | | .-. |
--- 1.0u --- 1.0u --- 1.0u --- 1.0u | | | +
--- --- --- --- 3.3k| | --- 2 caps
| | | | See '-' --- 3200uF
| | | | note | | total
=== === === === below === ===
GND GND GND GNF GND GND

Note: 2 BAV21 diodes are in series with the 3.3k to give another
1.2V
drop, to put more negative bias on the gate. Total drop across all
3 is
about 2 V.

Try this circuit:

+9V
|
.-.
| |
22K | |
'-'
|
.-------------------------------------------o-------------O
V out
| |
| 0.33uf 0.33uf 0.33uf |
| || || || |-
'---||--o--||--o--||--o------------------>| JFET MPF102
|| | || | || | |-
| | | |
\ \ \ o----.
1M / 1M / 1M / | |
\ \ \ .-. |
/ / / | | |
| | | 22K| | --- 3.3uf
| | | '-' ---
=== === === | |
GND GND GND === ===
GND GND

You have to give the poor little MPF102 a break, and bias it properly.
It needs about -5V Vgs to operate, so you need to up your source
resistor
to be equal to your drain resistor, if you want it to run at 9V.

Well, that was what I mentioned in another followup. According to the
specs, the MPF102 can have a Vgs of anywhere from .5V to 7.5V; that's a
ratio of fifteen to one. In the case of the FET I chose, it seems to be
working pretty good at about 1.5 V. But I'll vary it to see what effect
it has.

The 330k and 1uF sections of my schem, and the 1M and .33uF sections of
your schem have the same net effect because they are both loaded by the
gate, which is nearly infinite impedance, so the gate is negligible.
And since in both cases the impedance of the RC net is more than ten
times the drain load resistor, the RC net has negligible loading effect
in the drain resistor. Do you agree with this? If so, then it seems
that there should be no need to change from 330k and 1 uF to 1M and .33
uF RC sections.

So after all this, it comes down to the number of sections, mine with
four, and yours with three. I tried the three sections, and I could
barely tell that there was some overshoot on the output waveform, it was
_very_ damped. So there was a serious need for more gain or less
attenuation. So I went with four sections to get less attenuation.

And I tried the 22k drain load resistor, but it was still too low.
Finally when I got up into the high 20s I started to see some life in
the damped oscillation. At 33k it finally was able to sustain
oscillations. What I need to do now is fiddle with the source bias
resistor to get the waveform to clip symmetrically. So your suggestion
of changing the Vgs looks like it'll be one key to get the waveform
looking reasonable.

Thanks.

Also, with this type of oscillator, you need a gain of at least 29 to
make it oscillate. Gain is approximately Rd/gm, gm for this fet is
only about 2000 uS

-Chuck Harris