Date   
Re: Stopping Lights from Strobing

Richard Knoppow
 

I found instructions for repairing LED household light bulbs on You Tube. Don't have the links handy. Pry off the top and replace the bad LEDs inside with good ones from another failed bulb. Not that much work but aside from being a curiosity not worth the time.
I have a number of LED lamps, LADWP sends me free ones every so often. Biggest problem is that they are somewhat larger than the incandescent lamps they replace and don't quite fit into some older lamps.

On 7/15/2018 12:08 PM, Artekmedia wrote:
So far I have not had great luck with LED replacement bulbs built by CREE sold by one of the big box hardware stores. I used to send them back and get replacements  under warranty but as David says when you figure in the value of your time at the current lower prices it is not worth the effort. I took one of the 100W (equivalents) by Cree apart and found an amazing amount of engineering, There is a three terminal device in there, at least a dozen SMT resistors & diodes , a whopping big 33uf/350V electrolytic and a couple of dipped leaded silver micas, a small transformer even. Their is a tear down review of the 60W version here.
https://www.ledsmagazine.com/articles/2013/04/cree-60w-led-replacement-bulb-review-and-tear-down.html
--
Richard Knoppow
dickburk@...
WB6KBL

Re: Stopping Lights from Strobing

ArtekManuals
 

So far I have not had great luck with LED replacement bulbs built by CREE sold by one of the big box hardware stores. I used to send them back and get replacements  under warranty but as David says when you figure in the value of your time at the current lower prices it is not worth the effort. I took one of the 100W (equivalents) by Cree apart and found an amazing amount of engineering, There is a three terminal device in there, at least a dozen SMT resistors & diodes , a whopping big 33uf/350V electrolytic and a couple of dipped leaded silver micas, a small transformer even. Their is a tear down review of the 60W version here.

https://www.ledsmagazine.com/articles/2013/04/cree-60w-led-replacement-bulb-review-and-tear-down.html

I no longer buy the CREE versions since I have had at least 1/2 dozen failures in the first two years of use

-DC
manuals@...

On 7/15/2018 12:03 PM, David Hess wrote:
At least where I am now near St. Louis, voltage spikes kill
incandescent, LED, and CFL bulbs about equally with a half life of
about half a year so less expensive incandescent bulbs (or passive
ballasted linear fluorescent bulbs) are the most economical by far.

At least in my experience, trying to return failed LED bulbs under
warranty is a waste of effort.

On Sun, 15 Jul 2018 11:08:39 -0400, you wrote:

Now for CCFL and LEDS, well, no filament, so the failure mechanism (at
least completely for LEDS) is component failure generally due to
temperature (I ignore voltage spikes here). Some of the LED lamps get
rather hot, depending on whether the LED or the control electronics is
the problem heat source. We know what that does to the electronics.
Cheaply made is also a factor, of course. Anything in the commodity
market is generally made for lowest cost to manufacture traded off
against an acceptable failure/return rate.
--
Dave
Manuals@...
www.ArtekManuals.com

Re: Homemade tunnel diodes

 

The part I find annoying is now I have to qualify new parts from
someone else which means going through a lot of datasheets. I wish
someone had at least picked up the HP/Avago parts.

One advantage of the HP parts was extensive documentation in old
datasheets and application notes which is lacking for the
alternatives.

On Sun, 15 Jul 2018 11:05:19 -0700, you wrote:

Yep, Broadcom Ltd. continues to shed product lines and employees.  They shed me a couple years ago, but haha, I got a better job immediately, took their severance package, and got 2 months off with pay due to the WARN Act!  Best thing that ever happened to me!
Just a shame that corporate raider Hock Tan is gutting yet another great company.....   Not good for the USA.

7912AD GPIB interface question

Adrian
 

Hi Folks,
The 7912AD is still running nicely as far as it's basic operation is concerned but this thing will not listen or talk to me!
It responds to the GPIB bus in that it switches to 'REMOTE' on receiving any 'set' or 'query' command sent to it's address but beyond that - nothing.
SRQ is asserted but nothing will read or clear that either.
I have checked the internal 'delimiter' link and it is set for EOI and other than that and the primary and secondary address switches, I haven't spotted anything in the hardware to set up?
I must have 30-40 GPIB instruments all of which I use happily with a Prologix Ethernet adaptor mostly with either EasyGPIB or AutoIT scripts so I think the 'system' is ok.
Have I missed something glaringly obvious about initializing it perhaps?

Any insights gratefully received - before I start the tedious business of putting a 7D01+DF2 GPIB analyser on the bus (and remembering how to drive it!)

TIA Adrian

Re: Homemade tunnel diodes

Jim Ford
 

Yep, Broadcom Ltd. continues to shed product lines and employees.  They shed me a couple years ago, but haha, I got a better job immediately, took their severance package, and got 2 months off with pay due to the WARN Act!  Best thing that ever happened to me!
Just a shame that corporate raider Hock Tan is gutting yet another great company.....   Not good for the USA.


Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: David Hess <@DWH> Date: 7/15/18 8:27 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Homemade tunnel diodes
And we have modern replacements for sampler diodes in the form of low
voltage low capacitance microwave mixing diodes.  Although Avago (old
HP and now Broadcom) has discontinued theirs, they are still readily
available from others.

On Sat, 14 Jul 2018 13:27:29 -0700, you wrote:

But "sampler diodes" are not tunnel diodes?

Re: Shipping Scope-Mobiles

 

On Thu, 12 Jul 2018 10:38:36 -0700, you wrote:

Scope carts can either be expensive because the seller considers them valuable, or they can be given away for practically nothing because the owner no longer has room for them. A scope cart takes up a lot of room compared to putting a scope on a desk and scopes are getting smaller.
I got all of my Scope-Mobiles from the vacuum tube era and a 203 with
the TM500 shelves this way. Given how heavy the 500 series
oscilloscopes are, having a Scope-Mobile for each one is well worth
it.

Best place to look for one is at a ham swap meet. Around the time the swap meet is about to close the sellers get desperate to sell a cart, if they brought one, rather than haul it back home, so you have a lot of negotiating leverage at that point.
I got another 203 with my 7603 this way at the TRW swap meet in
Manhattan Beach, California.

Re: Stopping Lights from Strobing

Michael A. Terrell
 

Two things:

1: I doubt that most of you ever worked on a 16mm film projector. The TP66 Film Chain Projectors used at TV stations had a small Variac to set the filament voltage on the projector bulbs for maximum life. These projectors had an automatic bulb changer. The current through the filament held in a series relay. A motor would mover the track up or down to the second bulb, and stop only when it found a good filament. I quickly discovered that the primary bulb needed to be the one on to, for maximum bulb life. The waste heat went out the top of that channel, so slamming a hot bulb into position shortened its life.

You had to balance lamp life to video quality but I routinely got 130 hours out of 20 hour rated bulbs since we were only a B&W station. Also, the bulb used to read the sound track was operated at above 20KHz to provide clean sound. DC supplies would drift, and some low frequency noise would leak through them so they were fed from an oscillator.

2: I need a light of light, due to poor vision. Sometimes a magnifying light gets in the way, so I bought a cheap articulated microphone holder and slipped one of the Harbor Freight 9 LED flashlights into the mic holder. One of them is on the shelf above my computer monitor to read part numbers, and other small print.

They can be bought for $10 on Ebay. I cut down one of the flashlights so I can solder some wires to the LED module. It will be connected to a constant current supply, and the wires will run through the hollow tune, like a microphone cable would. Here is an example of what I bought:

https://www.ebay.com/itm/302765011048
New-Mic-Microphone-Suspension-Boom-Scissor-Arm-Stand-Holder-for-Studio-Broadcast/

Michael A. Terrell

-----Original Message-----
From: Bert Haskins <bhaskins@...>
Sent: Jul 15, 2018 9:09 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Stopping Lights from Strobing

On my solder station bench I had a drafting lamp with two 20 w tubes
that were a real pita.
I really liked the fixture so I replaced the tubes with dual row led
strips powered by a adjustable 12v smps.
Later I added a dimmer.
This ended up being just about all anyone could ask for, just the right
amount of light positioned just where you want it.

There is much less glare because the light comes from so many points.

These strips can be very versatile, they can be cut and resoldered for
use on 12, 24, 36... volts all the way up to (rectified) 120 AC.

I can furnish pictures upon request.

-- Bert

On 7/14/2018 11:29 PM, Michael A. Terrell wrote:
LEDs don't flicker when fed with clean, filtered DC. The light fixture in my bedroom has three LED bulbs under the ceiling fan and they don't flicker under normal usage. Just before they fail, I have had some start to flash at irregular intervals. All of the LED lamps I've see tell you not to operate them base up, but the only sockets that are base down seem to be table lamps and some outside lamps. I first installed some puny 1.5W LED lamps at the gateposts for my driveway. They were still working when I replaced them with some 7 watt bulbs. In total, there have been LED lamps there for over 15 years without a failure but it is cool when they are on. I've had two failures in two years in my bedroom where they started to flash, then they died.

Re: Concentric A and B time-base knobs/interlocking

Colin Herbert
 

Thanks for this, Tom, but I think my 466 (serial #B124248 is a bit later, as the innards don't look much like what is shown. I think I'll have to remove the Trigger generator and Sweep Logic board to get a better view.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Tom Gardner
Sent: 15 July 2018 14:46
To: TekScopes@groups.io
Subject: Re: [TekScopes] Concentric A and B time-base knobs/interlocking

On 15/07/18 14:13, Colin Herbert via Groups.Io wrote:
Hi,
I thought that I recalled some discussion on dismantling these A and B time-base knobs safely, but I can't find it now. My problem is that I have a 466 which looks to be fine so far, except for the B (delayed) time-base settings. The A time-base looks to be ok (thought I haven't checked its calibration fully), but pulling out the knob to select the delayed time-base settings results in the knob simply turning freely with no detent positions. Also, the knob cannot be turned to the locked position while pulled out, only when released back to the "in" position. I thought that I had seen a "bright-up" spot when switching to "A INTEN" which could be moved with the delay time position control, but this can't be seen now. There is no evidence of a B sweep at all; the "BEAM FINDER" button only shows a bright spot.
I have tried removing the knobs on another dual time-base some time ago and found it troublesome to put it back together again, to say the least. Does anyone have any hints for me?
TIA, Colin.
475 rather than 466:
http://www.eevblog.com/forum/repair/renovating-an-early-tektronix-475-oscilloscope-a-few-random-hints-and-tips/

Does anybody have a 7D10 Plugin?

 

Does anybody have a Tek 7D10 Digital Delay plugin for the 7000 series lab
scopes that they want to sell or trade?

I've been looking on Ebay for over a year and none have shown up.



It is a pretty specialized plugin and it was quickly superseded by the 7D11
which did what the 7D10 did and several more things as well so I suspect not
too many were sold before the 7D11 replaced it.



If you can help please contact me off list at @Dennis_Tillman_W7PF
<mailto:@Dennis_Tillman_W7PF>



Dennis Tillman W7PF

Re: Stopping Lights from Strobing

 

At least where I am now near St. Louis, voltage spikes kill
incandescent, LED, and CFL bulbs about equally with a half life of
about half a year so less expensive incandescent bulbs (or passive
ballasted linear fluorescent bulbs) are the most economical by far.

At least in my experience, trying to return failed LED bulbs under
warranty is a waste of effort.

On Sun, 15 Jul 2018 11:08:39 -0400, you wrote:

Now for CCFL and LEDS, well, no filament, so the failure mechanism (at
least completely for LEDS) is component failure generally due to
temperature (I ignore voltage spikes here). Some of the LED lamps get
rather hot, depending on whether the LED or the control electronics is
the problem heat source. We know what that does to the electronics.
Cheaply made is also a factor, of course. Anything in the commodity
market is generally made for lowest cost to manufacture traded off
against an acceptable failure/return rate.

Re: Stopping Lights from Strobing

 

Using a diode in series works well for porch lights which do not need
to be as bright anyway. The effect on operating life is much greater
than the effect on efficiency and brightness:

https://en.wikipedia.org/wiki/Incandescent_light_bulb#Light_output_and_lifetime

Light output is approximately proportional to V^3.4
Power consumption is approximately proportional to V^1.6
Lifetime is approximately proportional to V^-16 (!)
Color temperature is approximately proportional to V^0.42

That inversely proportional to the 16th power for operating life
neatly explains 130 volt "long life" bulbs.

On Sun, 15 Jul 2018 17:39:06 +0200, you wrote:

With incandescent bulbs you could put a diode in series and it would
last almost forever.
Efficiency was probably really crappy, but it still gave reasonable
(if a bit flickery) light output.

I've run such modified lights for many years, and I have even read
that you could buy a coin shaped diode insert in the US for just this
purpose.
No need to mention what too much of such nonsense would do to nearby
transformers.

Re: OT: Scopes and other electronics on "The Outer Limits"

 

On Wed, 11 Jul 2018 13:11:14 -0700, you wrote:

Too much Tektronix and I will start seeing them everywhere. like TVs, when I saw a TV on TV I would say "that's about a five year old Zenith", they had one on Bewitched.
The recent series Chance with Hugh Laurie had a Tektronix 465M or 465
variant in the back room of the antique furniture shop for some
reason.

It was a good series, but unlike most things that got resurrected, I think the 1990s series was better. I think the writing was better than any Star Trek, certain episodes anyway. They also had more of a budget, the documentary on the original said their budget was about a shoestring. Neither series wasted alot of money on special effects, which seems to be common these days. I mean they are just about to the point where they don't need actors. I shit you not, look at some of the video games these days.
They were using stories from actual science fiction writers. Larry
Niven wrote Inconsistent Moon which was episode 12 of season 2.

Re: Stopping Lights from Strobing

stefan_trethan
 

With incandescent bulbs you could put a diode in series and it would
last almost forever.
Efficiency was probably really crappy, but it still gave reasonable
(if a bit flickery) light output.

I've run such modified lights for many years, and I have even read
that you could buy a coin shaped diode insert in the US for just this
purpose.
No need to mention what too much of such nonsense would do to nearby
transformers.

ST

On Sun, Jul 15, 2018 at 5:08 PM, Harvey White <madyn@...> wrote:
On Sun, 15 Jul 2018 08:54:08 +0000 (UTC), you wrote:

I made a fixture years ago for working under the car at night. Three 150W bulbs in ceramic bases. Not only could I see everything, but it warmed up the carport in the winter!
CFLs are terrible. I do have some that have lasted a while, but most last about a year. I have incandescents that I haven't changed in ten+ years. One in a hallway is about 20 years old and still kicking.
The failure mechanism in an incandescent light is mainly related to
filament thinning as the tungsten evaporates slowly and is deposited
on the inside of the glass bulb. Eventually, the inrush current gets
that small higher resistance point up to where the filament just plain
melts.

For incandescents, the lifetime is related to the rated voltage to
applied voltage ratio. 10% more voltage, from what I've heard,
results in almost 1/10 the lifetime. 10% less, and you have a very
long life bulb. For those with choices, and 120 volts household (mine
is 122 to 123), use a 130 volt bulb to get very long life.

Now for CCFL and LEDS, well, no filament, so the failure mechanism (at
least completely for LEDS) is component failure generally due to
temperature (I ignore voltage spikes here). Some of the LED lamps get
rather hot, depending on whether the LED or the control electronics is
the problem heat source. We know what that does to the electronics.
Cheaply made is also a factor, of course. Anything in the commodity
market is generally made for lowest cost to manufacture traded off
against an acceptable failure/return rate.

There are carbon filament light bulbs (low temperature) that have been
operating for over fifty years. I have a fiber optics light source
for a microscope that has been working for several years (not
continuous), and is permanently set on the "LOW" setting.

Harvey

Re: Homemade tunnel diodes

 

And we have modern replacements for sampler diodes in the form of low
voltage low capacitance microwave mixing diodes. Although Avago (old
HP and now Broadcom) has discontinued theirs, they are still readily
available from others.

On Sat, 14 Jul 2018 13:27:29 -0700, you wrote:

But "sampler diodes" are not tunnel diodes?

Re: Stopping Lights from Strobing

Harvey White
 

On Sun, 15 Jul 2018 08:54:08 +0000 (UTC), you wrote:

I made a fixture years ago for working under the car at night.  Three 150W bulbs in ceramic bases.  Not only could I see everything, but it warmed up the carport in the winter!    
CFLs are terrible.  I do have some that have lasted a while, but most last about a year.  I have incandescents that I haven't changed in ten+ years.  One in a hallway is about 20 years old and still kicking.
The failure mechanism in an incandescent light is mainly related to
filament thinning as the tungsten evaporates slowly and is deposited
on the inside of the glass bulb. Eventually, the inrush current gets
that small higher resistance point up to where the filament just plain
melts.

For incandescents, the lifetime is related to the rated voltage to
applied voltage ratio. 10% more voltage, from what I've heard,
results in almost 1/10 the lifetime. 10% less, and you have a very
long life bulb. For those with choices, and 120 volts household (mine
is 122 to 123), use a 130 volt bulb to get very long life.

Now for CCFL and LEDS, well, no filament, so the failure mechanism (at
least completely for LEDS) is component failure generally due to
temperature (I ignore voltage spikes here). Some of the LED lamps get
rather hot, depending on whether the LED or the control electronics is
the problem heat source. We know what that does to the electronics.
Cheaply made is also a factor, of course. Anything in the commodity
market is generally made for lowest cost to manufacture traded off
against an acceptable failure/return rate.

There are carbon filament light bulbs (low temperature) that have been
operating for over fifty years. I have a fiber optics light source
for a microscope that has been working for several years (not
continuous), and is permanently set on the "LOW" setting.

Harvey


-Dave

From: stefan_trethan <stefan_trethan@...>
To: TekScopes@groups.io
Sent: Saturday, July 14, 2018 11:03 PM
Subject: Re: [TekScopes] Stopping Lights from Strobing

According to an EU study, which assumed only 20% recycling, CFLs still
release less mercury than incandescent bulbs, if you account for the
mercury emissions by coal power plants which made up about 30% of
power generation at the time.

But luckily we have LED now, those CFLs really sucked.

I too have a cache of incandescent bulbs. Many stupid people like
myself bought a bunch when their sale was about to be restricted and
prices were already high. Unlikely I will ever use them, already you
see fixtures that aren't designed thermally for any more than 20W or
so.

ST

On Sun, Jul 15, 2018 at 7:25 AM, musicamex <musicamex@...> wrote:
  I wonder how
much mercury based lighting actually is disposed of without release of the
Hg into the environment.. I do have a small cache of filament bulbs, mainly
for current limiters.  I'm sure enough to outlast me.

Russ






Re: Concentric A and B time-base knobs/interlocking

Tom Gardner
 

On 15/07/18 14:13, Colin Herbert via Groups.Io wrote:
Hi,
I thought that I recalled some discussion on dismantling these A and B time-base knobs safely, but I can't find it now. My problem is that I have a 466 which looks to be fine so far, except for the B (delayed) time-base settings. The A time-base looks to be ok (thought I haven't checked its calibration fully), but pulling out the knob to select the delayed time-base settings results in the knob simply turning freely with no detent positions. Also, the knob cannot be turned to the locked position while pulled out, only when released back to the "in" position. I thought that I had seen a "bright-up" spot when switching to "A INTEN" which could be moved with the delay time position control, but this can't be seen now. There is no evidence of a B sweep at all; the "BEAM FINDER" button only shows a bright spot.
I have tried removing the knobs on another dual time-base some time ago and found it troublesome to put it back together again, to say the least. Does anyone have any hints for me?
TIA, Colin.
475 rather than 466:
http://www.eevblog.com/forum/repair/renovating-an-early-tektronix-475-oscilloscope-a-few-random-hints-and-tips/

Re: Stopping Lights from Strobing

ebrucehunter
 

About 40 years ago an engineer at Stanford University demonstrated the importance of running florescent light fixtures in a three-phase pattern where the three tubes in a fixture were connected to separate phases so as to minimizing the strobing effect. As I recall they were in the process of converting classroom lighting to this configuration. He showed me the improvement with a simple silicon photodiode connected to an oscilloscope.

Bruce, KG6OJI

Concentric A and B time-base knobs/interlocking

Colin Herbert
 

Hi,
I thought that I recalled some discussion on dismantling these A and B time-base knobs safely, but I can't find it now. My problem is that I have a 466 which looks to be fine so far, except for the B (delayed) time-base settings. The A time-base looks to be ok (thought I haven't checked its calibration fully), but pulling out the knob to select the delayed time-base settings results in the knob simply turning freely with no detent positions. Also, the knob cannot be turned to the locked position while pulled out, only when released back to the "in" position. I thought that I had seen a "bright-up" spot when switching to "A INTEN" which could be moved with the delay time position control, but this can't be seen now. There is no evidence of a B sweep at all; the "BEAM FINDER" button only shows a bright spot.
I have tried removing the knobs on another dual time-base some time ago and found it troublesome to put it back together again, to say the least. Does anyone have any hints for me?
TIA, Colin.

Re: Stopping Lights from Strobing

Bert Haskins
 

On my solder station bench I had a drafting lamp with two 20 w tubes that were a real pita.
I really liked the fixture so I replaced the tubes with dual row led strips powered by a adjustable 12v smps.
Later I added a dimmer.
This ended up being just about all anyone could ask for, just the right amount of light positioned just where you want it.

There is much less glare because the light comes from so many points.

These strips can be very versatile, they can be cut and resoldered for use on 12, 24, 36... volts all the way up to (rectified) 120 AC.

I can furnish pictures upon request.

-- Bert

On 7/14/2018 11:29 PM, Michael A. Terrell wrote:
LEDs don't flicker when fed with clean, filtered DC. The light fixture in my bedroom has three LED bulbs under the ceiling fan and they don't flicker under normal usage. Just before they fail, I have had some start to flash at irregular intervals. All of the LED lamps I've see tell you not to operate them base up, but the only sockets that are base down seem to be table lamps and some outside lamps. I first installed some puny 1.5W LED lamps at the gateposts for my driveway. They were still working when I replaced them with some 7 watt bulbs. In total, there have been LED lamps there for over 15 years without a failure but it is cool when they are on. I've had two failures in two years in my bedroom where they started to flash, then they died.


Michael A. Terrell


-----Original Message-----
From: brians@...
Sent: Jul 14, 2018 10:31 PM
To: TekScopes@groups.io
Subject: [TekScopes] Stopping Lights from Strobing

Many years ago when I was a 'lecky, I worked on a very expensive lathe light fitting that was using fluorescent tubes.

I was amazed that a lathe actually had a fluorescent fitting because of strobe concerns but I found that the manufacturer "cheated" a bit for safety reasons.
Fluorescent light fittings In most commercial use locations have power factor correction capacitors fitted directly across the connection terminals otherwise the power metering will not be correct & there can be circulating current problems.
The manufacturer of the lathe fluorescent light fitting used a dual fluorescent light fitting with two separate ballasts & only had a power factor correction capacitor fitted to the one one fluorescent light.

The power factor correction capacitor caused a phase shift on the one lamp compared to the other.
I actually ran the fitting with no power factor correction capacitors fitted at all & with the one fitted & when the one capacitor was fitted then the strobe effect was not visible.

I suppose that it may be possible to phase shift some LED lamps as well with a capacitor if they use an actual iron transformer for the power supply so you could have dual LED lamps set up in a similar way.

Re: OT: LED lamp bulbs at ridiculously low prices at (some) Costco stores

cmjones01
 

On Sun, 15 Jul 2018, 11:52 David C. Partridge, <
@perdrix> wrote:

UK TV: 50Hz half frame, interlaced full frame was 25Hz.
It still is, though in digital HD these days.

Back to the topic, LED bulbs vary wildly in their behaviour and quality.
Cheap ones can and do flicker because they often use a capacitive dropper
and no filtering. Our house is full of fairly nasty LED bulbs that the
landlord installed and they flicker horribly.

More expensive bulbs with better power supply arrangements don't flicker.
Perhaps the nicest we have here are some I put in our bathroom which are
those incandescent-style ones with the long 'bars' of LEDs inside. I don't
know whether they use a better power supply or just a longer persistence
phosphor, but they don't flicker and even have something of an afterglow
after switching off. Inside opal white globes they give a really nice warm
light, something like that from a gas mantle.

Chris