Driver to drive?

[Jasen Betts]

On 2015-10-13, John Smith <invalid@invalid.invalid> wrote:

makolber@yahoo.com> wrote in message
news:f2476cda-9474-4878-9361-0c39a9518e5e@googlegroups.com...
It could be a failed tant cap across a power buss.
At the very least you should be able to isolate this channel and have a 23
channel mixer.
Mark

I'll wait and see what the customer wants to do.

Taking the board off will be the only way to see exactly what component
failed, but why so much board area?
It's almost like heat started something and it spread. Did the board go
conductive with heat?

Graphite is conductive, so yeah, once the resin, or solder-mask, is
hot enough to form charcoal the damage will spread.

--
\_(ツ)_

 

On Wednesday, 14 October 2015 08:08:53 UTC+1, daku...@gmail.com wrote:

May I ask all you gurus on yjis newsgroup.
What do think about the following:
http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/

OR
http://www.instructables.com/id/Fully-Functional-Television-Oscilloscope/

Not sure if it is that easy -- so I ask.
Thanks in advance.

It is that easy. I'm told it's also easy for the crt to go bang due to the electron stream overheating the glass at the neck.


NT

 

On Wednesday, 14 October 2015 11:30:53 UTC+1, Jasen Betts wrote:

On 2015-10-14, dakupoto@gmail.com <dakupoto@gmail.com> wrote:
May I ask all you gurus on yjis newsgroup.
What do think about the following:
http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/

OR
http://www.instructables.com/id/Fully-Functional-Television-Oscilloscope/

Not sure if it is that easy -- so I ask.
Thanks in advance.

yeah, it's about that easy. but one of those $25 pocket digital
osciloscope kits might be more useful, a TV oscilloscope can
barely handle audio frequency signals.

the timebase is 15kHz, and the video bandwidth 6MHz.


NT

 

[Jasen Betts]

On 2015-10-14, dakupoto@gmail.com <dakupoto@gmail.com> wrote:

May I ask all you gurus on yjis newsgroup.
What do think about the following:
http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/

OR
http://www.instructables.com/id/Fully-Functional-Television-Oscilloscope/

Not sure if it is that easy -- so I ask.
Thanks in advance.

yeah, it's about that easy. but one of those $25 pocket digital
osciloscope kits might be more useful, a TV oscilloscope can
barely handle audio frequency signals.


--
\_(ツ)_

 

[Michael Kellett]

dakupoto:

May I ask all you gurus on yjis newsgroup.
What do think about the following:

http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/

OR

http://www.instructables.com/id/Fully-Functional-Television-Oscilloscope/

Not sure if it is that easy -- so I ask.
Thanks in advance.

You don't end up with a scope but a fairly useless curiosity which you
may or may not find amusing to play with. The only way to turn a CRT
into a proper scope is to use it as the display for a conventional
digital scope - this probably isn't worth the effort any more.
Every now and again I see huge CRTs being dumped at the local tip and I
have urges to rescue them and put them to work but I'm getting over it


MK

 

[DecadentLinuxUserNumeroUn]

On 14 Oct 2015 09:50:15 GMT, Jasen Betts <jasen@xnet.co.nz> Gave us:

On 2015-10-14, dakupoto@gmail.com <dakupoto@gmail.com> wrote:
May I ask all you gurus on yjis newsgroup.
What do think about the following:
http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/

OR
http://www.instructables.com/id/Fully-Functional-Television-Oscilloscope/

Not sure if it is that easy -- so I ask.
Thanks in advance.

yeah, it's about that easy. but one of those $25 pocket digital
osciloscope kits might be more useful, a TV oscilloscope can
barely handle audio frequency signals.

It would be like first year electronics experimentation regimen.

Not unlike building a crystal radio tuner by today's standards.

Better off buying a USB scope and using your PC display to examine the
probings.

 

[Phil Hobbs]

On 10/14/2015 06:40 AM, tabbypurr@gmail.com wrote:

On Wednesday, 14 October 2015 11:30:53 UTC+1, Jasen Betts wrote:
On 2015-10-14, dakupoto@gmail.com <dakupoto@gmail.com> wrote:
May I ask all you gurus on yjis newsgroup.
What do think about the following:
http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/

OR
http://www.instructables.com/id/Fully-Functional-Television-Oscilloscope/

Not sure if it is that easy -- so I ask.
Thanks in advance.

yeah, it's about that easy. but one of those $25 pocket digital
osciloscope kits might be more useful, a TV oscilloscope can
barely handle audio frequency signals.

the timebase is 15kHz, and the video bandwidth 6MHz.


NT

And in oscilloscope mode, you need the vertical deflection to respond at
the video rate, not just the intensity.

Magnetic deflection produces much better focused spots than
electrostatic, but is much much slower. The reason for the badness of
electrostatic focusing is actually pretty interesting: because the field
obeys Laplace's equation, it cannot have a maximum value except at the
boundary. Thus you can't make negative lenses, which means you can't
correct aberrations.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[John Devereux]

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> writes:

On 10/14/2015 06:40 AM, tabbypurr@gmail.com wrote:
On Wednesday, 14 October 2015 11:30:53 UTC+1, Jasen Betts wrote:
On 2015-10-14, dakupoto@gmail.com <dakupoto@gmail.com> wrote:
May I ask all you gurus on yjis newsgroup.
What do think about the following:
http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/

OR
http://www.instructables.com/id/Fully-Functional-Television-Oscilloscope/

Not sure if it is that easy -- so I ask.
Thanks in advance.

yeah, it's about that easy. but one of those $25 pocket digital
osciloscope kits might be more useful, a TV oscilloscope can
barely handle audio frequency signals.

the timebase is 15kHz, and the video bandwidth 6MHz.


NT


And in oscilloscope mode, you need the vertical deflection to respond
at the video rate, not just the intensity.

That was one of the first projects I tried as a teenager. As you suggest
it was severely limited in bandwidth. Looking back, it might have been a
lot better with compensation for the coil inductances. I guess a current
driver with as high an available voltage as feasible. Or just
pre-emphasize the signal I suppose.

Then I got an actual scope and the first thing was to make it show a TV
picture

Magnetic deflection produces much better focused spots than
electrostatic, but is much much slower. The reason for the badness of
electrostatic focusing is actually pretty interesting: because the
field obeys Laplace's equation, it cannot have a maximum value except
at the boundary. Thus you can't make negative lenses, which means you
can't correct aberrations.

Cheers

Phil Hobbs

--

John Devereux

 

On Wednesday, 14 October 2015 14:06:20 UTC+1, Phil Hobbs wrote:

On 10/14/2015 06:40 AM, nt wrote:
On Wednesday, 14 October 2015 11:30:53 UTC+1, Jasen Betts wrote:
On 2015-10-14, dakupoto@gmail.com <dakupoto@gmail.com> wrote:

May I ask all you gurus on yjis newsgroup.
What do think about the following:
http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/

OR
http://www.instructables.com/id/Fully-Functional-Television-Oscilloscope/

Not sure if it is that easy -- so I ask.
Thanks in advance.

yeah, it's about that easy. but one of those $25 pocket digital
osciloscope kits might be more useful, a TV oscilloscope can
barely handle audio frequency signals.

the timebase is 15kHz, and the video bandwidth 6MHz.

And in oscilloscope mode, you need the vertical deflection to respond at
the video rate, not just the intensity.

You can run it both ways, depending on the bandwidth needed. You can also use an envelope detector to go even higher in frequency - at least for some apps.

Magnetic deflection produces much better focused spots than
electrostatic, but is much much slower. The reason for the badness of
electrostatic focusing is actually pretty interesting: because the field
obeys Laplace's equation, it cannot have a maximum value except at the
boundary. Thus you can't make negative lenses, which means you can't
correct aberrations.

Cheers

Phil Hobbs

Can concentric rings with opposite polarity not achieve that?


NT

 

[Tim Wescott]

On Wed, 14 Oct 2015 11:05:39 +0100, Michael Kellett wrote:

dakupoto:
May I ask all you gurus on yjis newsgroup.
What do think about the following:

http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-
Oscilloscope/

OR

http://www.instructables.com/id/Fully-Functional-Television-
Oscilloscope/

Not sure if it is that easy -- so I ask. Thanks in advance.

You don't end up with a scope but a fairly useless curiosity which you
may or may not find amusing to play with. The only way to turn a CRT
into a proper scope is to use it as the display for a conventional
digital scope - this probably isn't worth the effort any more.
Every now and again I see huge CRTs being dumped at the local tip and I
have urges to rescue them and put them to work but I'm getting over it

You can use them as finals in audio amplifiers, apparently. I haven't
done this, but I'm assuming that you get both sound and light from the
effort.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 

On Wednesday, 14 October 2015 20:25:09 UTC+1, Phil Hobbs wrote:

On 10/14/2015 03:18 PM, nt wrote:
On Wednesday, 14 October 2015 14:06:20 UTC+1, Phil Hobbs wrote:
On 10/14/2015 06:40 AM, nt wrote:
On Wednesday, 14 October 2015 11:30:53 UTC+1, Jasen Betts
wrote:
On 2015-10-14, dakupoto@gmail.com <dakupoto@gmail.com> wrote:

May I ask all you gurus on yjis newsgroup. What do think
about the following:
http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/



OR
http://www.instructables.com/id/Fully-Functional-Television-Oscilloscope/



Not sure if it is that easy -- so I ask.
Thanks in advance.

yeah, it's about that easy. but one of those $25 pocket
digital osciloscope kits might be more useful, a TV
oscilloscope can barely handle audio frequency signals.

the timebase is 15kHz, and the video bandwidth 6MHz.

And in oscilloscope mode, you need the vertical deflection to
respond at the video rate, not just the intensity.

You can run it both ways, depending on the bandwidth needed. You can
also use an envelope detector to go even higher in frequency - at
least for some apps.

Magnetic deflection produces much better focused spots than
electrostatic, but is much much slower. The reason for the badness
of electrostatic focusing is actually pretty interesting: because
the field obeys Laplace's equation, it cannot have a maximum value
except at the boundary. Thus you can't make negative lenses, which
means you can't correct aberrations.

Can concentric rings with opposite polarity not achieve that?

Nope. The potential always achieves its extreme values on the surface,
so there's no way to have a maximum in the middle, which is what you
need for a negative lens.

In optics optics, you can compensate for field curvature by keeping the
Petzval sum small--see
https://en.wikipedia.org/wiki/Petzval_field_curvature ,
but this doesn't work in electron optics, because you can't make the
equivalent of negative lenses. It's the classical problem of electron
optics.

Cheers

Phil Hobbs

What happens if we make the electrode a spot right in the middle, where the beam would hit it, then deflect the beam away with a magnet just before it does hit it? I can see this not working


NT

 

[Phil Hobbs]

On 10/14/2015 03:18 PM, tabbypurr@gmail.com wrote:

On Wednesday, 14 October 2015 14:06:20 UTC+1, Phil Hobbs wrote:
On 10/14/2015 06:40 AM, nt wrote:
On Wednesday, 14 October 2015 11:30:53 UTC+1, Jasen Betts
wrote:
On 2015-10-14, dakupoto@gmail.com <dakupoto@gmail.com> wrote:

May I ask all you gurus on yjis newsgroup. What do think
about the following:
http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/



OR
http://www.instructables.com/id/Fully-Functional-Television-Oscilloscope/



Not sure if it is that easy -- so I ask.
Thanks in advance.

yeah, it's about that easy. but one of those $25 pocket
digital osciloscope kits might be more useful, a TV
oscilloscope can barely handle audio frequency signals.

the timebase is 15kHz, and the video bandwidth 6MHz.

And in oscilloscope mode, you need the vertical deflection to
respond at the video rate, not just the intensity.

You can run it both ways, depending on the bandwidth needed. You can
also use an envelope detector to go even higher in frequency - at
least for some apps.

Magnetic deflection produces much better focused spots than
electrostatic, but is much much slower. The reason for the badness
of electrostatic focusing is actually pretty interesting: because
the field obeys Laplace's equation, it cannot have a maximum value
except at the boundary. Thus you can't make negative lenses, which
means you can't correct aberrations.

Cheers

Phil Hobbs

Can concentric rings with opposite polarity not achieve that?

Nope. The potential always achieves its extreme values on the surface,
so there's no way to have a maximum in the middle, which is what you
need for a negative lens.

In optics optics, you can compensate for field curvature by keeping the
Petzval sum small--see
https://en.wikipedia.org/wiki/Petzval_field_curvature ,
but this doesn't work in electron optics, because you can't make the
equivalent of negative lenses. It's the classical problem of electron
optics.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Robert Baer]

tabbypurr@gmail.com wrote:

On Wednesday, 14 October 2015 08:08:53 UTC+1, daku...@gmail.com wrote:
May I ask all you gurus on yjis newsgroup.
What do think about the following:
http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/

OR
http://www.instructables.com/id/Fully-Functional-Television-Oscilloscope/

Not sure if it is that easy -- so I ask.
Thanks in advance.

It is that easy. I'm told it's also easy for the crt to go bang due to the electron stream overheating the glass at the neck.


NT
That is total bullshit, and i am being polite.

 

I have tl494 in I ball amps in which I get 5 vsb & power on signal perfectly. But no output at 5 12 3.3etc
In pin4 tl494 I get 3.3 voltage what does it mean????? Please guide me .
How to check drive of push pull & ct rt oscillator.??????

 

[legg]

On Wed, 21 Oct 2015 03:41:57 -0700 (PDT), nimit580@gmail.com wrote:

I have tl494 in I ball amps in which I get 5 vsb & power on signal perfectly. But no output at 5 12 3.3etc
In pin4 tl494 I get 3.3 voltage what does it mean????? Please guide me .
How to check drive of push pull & ct rt oscillator.??????

The TL494's minimum operating supply voltage is 7V.

It has no internal undervoltage lock-out; supply current and pin
characteristics are undefined at start-up or when its supply voltage
is low.

Dead time control (DTC) pin 4 is an input that you are expected to
control, normally grounded for minimum deadtime.

RL

 

[Bill Sloman]

On Sunday, 4 October 2015 12:17:20 UTC+11, John Larkin wrote:

On Sat, 3 Oct 2015 17:38:38 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

On Saturday, October 3, 2015 at 3:58:16 PM UTC-4, John Larkin wrote:
On Sat, 3 Oct 2015 09:54:50 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

On Friday, October 2, 2015 at 4:18:02 PM UTC-4, John Larkin wrote:
On Thu, 01 Oct 2015 21:33:43 -0400, krw <krw@nowhere.com> wrote:

On Wed, 30 Sep 2015 16:09:17 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:



George H.
*an "el, e, dee", letters
or a "lead" one word?

Yes. As long as the context makes the meaning clear.

English is wonderful. Not only does it have something like 800K words,
each word can have many meanings, and different words sound exactly
alike.

"Lead" can be a noun or a verb or an adjective, present or past tense,
at least two pronunciations, and has lots of meanings.

There is a kinda weak connection between my written/read vocabulary
and my spoken/heard. When I write/read LED I "say" the letters
in my brain, but when I speak it, I'll say "lead"
(at least to other electronics people).
The same is true for pico-Farad and puff.
And then writing on SED I get further confused.
When we talk about electronics, I'm in writing mode.
But when it gets more chatty, like this, then
I picture myself talking to you... that seems more
intimate, and friendly. And I "write", as I would talk.

My brain is almost entirely visual and kinetic, and processes words
very poorly. I have a hard time mapping sounds into words, and accents
are terrible for me. Zero "cocktail party" effect. French almost
flunked me out of high school.

I read very well, unless the words try to mimic accents, at which I
guess my speech center gets called in to help figure things out, which
doesn't work.

Lots of techies have speech and hearing problems. My wife, the speech
pathologist, fixes lots of Google types.

I think and say ell e dee.




(Hmm, hey that explains why I dislike the flame wars
during chatty talks, more than disagreements over electronics.
When it's chatty, I want to be friendly, and all the
name calling disgusts me.)

Public forums attract repulsive, childish people who have no audience
in real life.

I'm going to disagree, SED seems like a pretty tight/ small
group at the moment.

There are flame threads that run to hundreds of posts. The same few
idiots making ritual, content-free insults.

John Larkin does have problems processing some of the content, and experiences anything that impugns his vanity (such as this) as a "content-free insult".

He's probably not the most reliable of reporters.

If we all stop responding to posts
with name calling, then I predict that behavior will stop.

I wouldn't bet on it.

> It won't stop, but we can ignore them.

But we don't.

(Or the person(s) who needs to name call will go somewhere else.)
I don't mind the OT political, food, talk as long as it's
polite.

Agreed. Engineers get hungry and thirsty too. SED is one of the few
active tech groups on usenet; most of usenet is dead.

And this would be a lot quieter without the off-topic flame wars. John Larkin's habit of posting off-topic links to denialist propaganda from the Murdoch media does help keep the group active - and no doubt feeds John Larkin's activity count. When I last looked he was our most prolific poster, well ahead of whoever was in second place.

--
Bill Sloman, Sydney

 

On Wednesday, September 23, 2015 at 5:35:01 AM UTC+10, bitrex wrote:

So I'm working on repairing a Korg MS2000B synthesizer for a friend with
a dead power supply. Here's the service manual:

http://www.loscha.com/scans/Korg_MS2000_Service_Manual.pdf

The first thing I notice when looking inside is that the small SMT 100uF
10V tantalum capacitor C109 has completely vacated - it appears to be
gone, blown right off the board. There are some little fragments
rattling around in the case.

I have little experience with tantalum capacitors. Any suggestions for
a more reliable replacement?

Just get an equivalent capacity tantalum that's rated to a higher voltage. Should last a lot longer.

 

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Add: Blk. 18, Longwangmiao Industry Park, Fuyong Tn., Bao’an Dist., Shenzhen 518103, Guangdong, China

 

[Sylvia Else]

Adding sci.electronics.design, which got left out by mistake.

On 29/10/2015 5:41 PM, Sylvia Else wrote:

I want to make something to detect whether there's direct sunlight
shining on particular place. I thought the obvious approach would be to
use a pair of light dependent resistors (LDR) - one located where it
will definitely be in direct sunlight (when the sun is shining) and
another that is at the location to be tested. Compare the resistances,
and the result should be clear enough.

But this means that at least one LDR will be in direct sunlight for
extended periods, and I can find nothing in the datasheets to indicate
whether the devices will survive that. My concern is UV degradation of
the encapsulation material.

I can put them behind glass, which will provide some protection, but
even then, they'll have to survive some UV.

Anyone have experience of this?

Sylvia.

 

[o pere o]

On 10/29/2015 09:25 AM, Sylvia Else wrote:

Adding sci.electronics.design, which got left out by mistake.

On 29/10/2015 5:41 PM, Sylvia Else wrote:

I want to make something to detect whether there's direct sunlight
shining on particular place. I thought the obvious approach would be to
use a pair of light dependent resistors (LDR) - one located where it
will definitely be in direct sunlight (when the sun is shining) and
another that is at the location to be tested. Compare the resistances,
and the result should be clear enough.

But this means that at least one LDR will be in direct sunlight for
extended periods, and I can find nothing in the datasheets to indicate
whether the devices will survive that. My concern is UV degradation of
the encapsulation material.

I can put them behind glass, which will provide some protection, but
even then, they'll have to survive some UV.

Anyone have experience of this?

Sylvia.

Perhaps you can use a small solar cell as the transducer? These should
survive direct sunlight during some decades.

Some time ago we even purchased a calibrated one, which could be used
for absolute measurements. I had a quick look but was unable to dig up
more details on it...

Pere