Topics

OT: Strobe lights - just a suggestion, no discussion needed

Ed Breya
 

In the recent thread about variacs, there was a tangent off to strobe lights.

Barry wrote:
"Coincidentally, I've been looking at getting one of those over the last few days. Unfortunate what the bulbs cost for them these days. I suppose if I watch long enough..."

You can get or build "modern" strobe lights based on high power lighting type LEDs, and not have to worry about the xenon lamps and powering them and controlling them. LEDs are much easier to deal with, and with modest voltages.

A few years ago I did some experimenting with LED strobing as an attachment to my coil winding machine project. I think I reported it here in the photos section. If I can find it easily, I'll post a link. Anyway, with just a small (6-12 LED cluster, don't recall exact size) warm-white LED module from a lighting fixture, I got decent viewing with normal ambient light, and had no trouble looking in detail at a router bit spinning around 25,000 RPM.

I had planned to (eventually) build a scaled up general purpose version with a large LED array. I have the rough design and parts set aside, but it's a low priority, since I don't often need a strobe, and I have a nice old regular Xe one that I had fixed at about that time too. If the repair of the old Xe had not turned out so easy - the flash head capacitor was shot , and had an intermittent wire - I would have probably junked it and built the LED version.

The xenon lamps have the edge in terms of peak power for a single device, but the LEDs win in terms of rep rate and pulse width control, and color temperature choice. The LED peak power (drive current) is limited to maybe 3-10 times normal, so you need lots of them for high brightness. They are easy to scale up in number, and I'm convinced they can way outperform xenon lamps for strobes.

Anyway, I believe there are by now lots of commercial LED-based strobes out there, yet another solid-state replacement of a "tube" technology.

Ed

Ed Breya
 

n4buq
 

Hi Ed,

I viewed the pictures in the album and I'd be interested in seeing more about this. The GR units are certainly cool but if I could make my own for a few dollars, that'd probably satisfy my curiousity. For now.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Ed Breya via groups.io" <edbreya=yahoo.com@groups.io>
To: TekScopes@groups.io
Sent: Saturday, June 27, 2020 6:44:19 PM
Subject: [TekScopes] OT: Strobe lights - just a suggestion, no discussion needed

In the recent thread about variacs, there was a tangent off to strobe lights.

Barry wrote:
"Coincidentally, I've been looking at getting one of those over the last few
days. Unfortunate what the bulbs cost for them these days. I suppose if I
watch long enough..."

You can get or build "modern" strobe lights based on high power lighting type
LEDs, and not have to worry about the xenon lamps and powering them and
controlling them. LEDs are much easier to deal with, and with modest
voltages.

A few years ago I did some experimenting with LED strobing as an attachment
to my coil winding machine project. I think I reported it here in the photos
section. If I can find it easily, I'll post a link. Anyway, with just a
small (6-12 LED cluster, don't recall exact size) warm-white LED module from
a lighting fixture, I got decent viewing with normal ambient light, and had
no trouble looking in detail at a router bit spinning around 25,000 RPM.

I had planned to (eventually) build a scaled up general purpose version with
a large LED array. I have the rough design and parts set aside, but it's a
low priority, since I don't often need a strobe, and I have a nice old
regular Xe one that I had fixed at about that time too. If the repair of the
old Xe had not turned out so easy - the flash head capacitor was shot , and
had an intermittent wire - I would have probably junked it and built the LED
version.

The xenon lamps have the edge in terms of peak power for a single device, but
the LEDs win in terms of rep rate and pulse width control, and color
temperature choice. The LED peak power (drive current) is limited to maybe
3-10 times normal, so you need lots of them for high brightness. They are
easy to scale up in number, and I'm convinced they can way outperform xenon
lamps for strobes.

Anyway, I believe there are by now lots of commercial LED-based strobes out
there, yet another solid-state replacement of a "tube" technology.

Ed






 

Hi Ed,
A stroboscope or LED Strobe like you made (great idea!) has so much in common with an oscilloscope that I knew I had to get a Strobotac after seeing how it brought repetitive mechanical motion to a standstill in front of my eyes. This is exactly what an oscilloscope does.

Since, you showed a few pictures of your LED Strobe oversampling the spinning router bit it is worth mentioning there is a direct analogy to how digital scopes work. As long as the digital scope can sample repetitive mechanical motion twice as fast as the period of the motion there will be few problems understanding the results. This corresponds to the Nyquist Theorem where you are sampling at faster than 2X the period of the waveform being sampled.

But when the LED Strobe's sample rate is less than twice the rate at which the sample is vibrating or turning you are going to get aliasing results that can lead to erroneous conclusions about what your sample is doing. This all becomes perfectly clear right in front of your eyes when you can vary the strobe's speed and observe the effect it has on what you see.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed Breya via groups.io
Sent: Saturday, June 27, 2020 4:44 PM
To: TekScopes@groups.io
Subject: [TekScopes] OT: Strobe lights - just a suggestion, no discussion needed

In the recent thread about variacs, there was a tangent off to strobe lights.

Barry wrote:
"Coincidentally, I've been looking at getting one of those over the last few days. Unfortunate what the bulbs cost for them these days. I suppose if I watch long enough..."

You can get or build "modern" strobe lights based on high power lighting type LEDs, and not have to worry about the xenon lamps and powering them and controlling them. LEDs are much easier to deal with, and with modest voltages.

A few years ago I did some experimenting with LED strobing as an attachment to my coil winding machine project. I think I reported it here in the photos section. If I can find it easily, I'll post a link. Anyway, with just a small (6-12 LED cluster, don't recall exact size) warm-white LED module from a lighting fixture, I got decent viewing with normal ambient light, and had no trouble looking in detail at a router bit spinning around 25,000 RPM.

I had planned to (eventually) build a scaled up general purpose version with a large LED array. I have the rough design and parts set aside, but it's a low priority, since I don't often need a strobe, and I have a nice old regular Xe one that I had fixed at about that time too. If the repair of the old Xe had not turned out so easy - the flash head capacitor was shot , and had an intermittent wire - I would have probably junked it and built the LED version.

The xenon lamps have the edge in terms of peak power for a single device, but the LEDs win in terms of rep rate and pulse width control, and color temperature choice. The LED peak power (drive current) is limited to maybe 3-10 times normal, so you need lots of them for high brightness. They are easy to scale up in number, and I'm convinced they can way outperform xenon lamps for strobes.

Anyway, I believe there are by now lots of commercial LED-based strobes out there, yet another solid-state replacement of a "tube" technology.

Ed








--
Dennis Tillman W7pF
TekScopes Moderator

stevenhorii
 

The discussion of strobe lights and Harold Edgerton brought to mind his
work on the "Rapatronic" shutter which was used to take photographs of
early atomic tests. Here's ab it about the Rapatronic:

https://edgerton-digital-collections.org/techniques/rapatronic-shutter

If you are interested in seeing some of the photos and more techniques to
film atomic explosions (not trivial since the exposure range was huge)
there's a book titled "How to Photograph an Atomic Bomb" by Peter Curran.
The hardcover edition has gotten very expensive as it is nearly sold out
and won't be reprinted. The softcover edition is less expensive. If you
search the archive of this group, there were some threads from 2017 about
the use of Tektronix scopes for data acquisition during atomic testing.

Steve H.

On Sat, Jun 27, 2020 at 7:44 PM Ed Breya via groups.io <edbreya=
yahoo.com@groups.io> wrote:

In the recent thread about variacs, there was a tangent off to strobe
lights.

Barry wrote:
"Coincidentally, I've been looking at getting one of those over the last
few days. Unfortunate what the bulbs cost for them these days. I suppose if
I watch long enough..."

You can get or build "modern" strobe lights based on high power lighting
type LEDs, and not have to worry about the xenon lamps and powering them
and controlling them. LEDs are much easier to deal with, and with modest
voltages.

A few years ago I did some experimenting with LED strobing as an
attachment to my coil winding machine project. I think I reported it here
in the photos section. If I can find it easily, I'll post a link. Anyway,
with just a small (6-12 LED cluster, don't recall exact size) warm-white
LED module from a lighting fixture, I got decent viewing with normal
ambient light, and had no trouble looking in detail at a router bit
spinning around 25,000 RPM.

I had planned to (eventually) build a scaled up general purpose version
with a large LED array. I have the rough design and parts set aside, but
it's a low priority, since I don't often need a strobe, and I have a nice
old regular Xe one that I had fixed at about that time too. If the repair
of the old Xe had not turned out so easy - the flash head capacitor was
shot , and had an intermittent wire - I would have probably junked it and
built the LED version.

The xenon lamps have the edge in terms of peak power for a single device,
but the LEDs win in terms of rep rate and pulse width control, and color
temperature choice. The LED peak power (drive current) is limited to maybe
3-10 times normal, so you need lots of them for high brightness. They are
easy to scale up in number, and I'm convinced they can way outperform xenon
lamps for strobes.

Anyway, I believe there are by now lots of commercial LED-based strobes
out there, yet another solid-state replacement of a "tube" technology.

Ed