Forums

Xenon flash tube

Started by bitrex September 7, 2015
On Monday, September 7, 2015 at 5:20:20 PM UTC-7, bitrex wrote:
> I got several of these xenon flash tubes down at Rat Shack on sale for > less than 2 bucks each. > > http://www.radioshack.com/long-life-xenon-strobe-tube/2721145.html > > Anyone have a design for a junk box circuit that could be used for > experimenting with these, say firing them from a TTL logic output?
It's pretty trivial; just grab an automobile's ignition coil, a resistor and 12V supply, tap a pushbutton and it flashes. The primary side will have a few more volts than TTL likes, but a HV transistor (few hundred volts) will suffice.
In article <55ee29bc$0$20876$4c5ecfc7@frugalusenet.com>, bitrex
<bitrex@de.lete.earthlink.net> wrote:

> I got several of these xenon flash tubes down at Rat Shack on sale for > less than 2 bucks each. > > http://www.radioshack.com/long-life-xenon-strobe-tube/2721145.html > > Anyone have a design for a junk box circuit that could be used for > experimenting with these, say firing them from a TTL logic output?
I've done this, and have a lesson-learned: You need an optocoupler between the TTL (or CMOS) logic and the xenon flash circuitry. When I built the xenon flash for logic control, I used a CMOS logic signal to trigger a small SCR which controlled a capacitor discharging through a trigger transformer. Turns out that enough flash energy came backwards through the SCR gate to completely confuse the CMOS logic. The CMOS was not damaged, but didn't work either. The solution was to interpose a commodity 4N36 optocoupler: The coupler was driven by the logic, and in turn triggered the C106D SCR. Joe Gwinn
On Monday, September 7, 2015 at 8:26:45 PM UTC-4, John Larkin wrote:
> On Mon, 7 Sep 2015 20:20:14 -0400, bitrex > <bitrex@de.lete.earthlink.net> wrote: > > >I got several of these xenon flash tubes down at Rat Shack on sale for > >less than 2 bucks each. > > > >http://www.radioshack.com/long-life-xenon-strobe-tube/2721145.html > > > >Anyone have a design for a junk box circuit that could be used for > >experimenting with these, say firing them from a TTL logic output? > > Well, you apply 300 volts across the end leads, with electrolytic caps > to store as many joules as you think it can stand; that's not > specified. Wild guess might be 30ish.
We used to use one in a strobe. Big yellow cap from Sprague.. 5 uF, 400 V. George H.
> > Than apply a fast high-voltage spike to the center lead, through a > trigger transformer. > > Google images, schematic photoflash. TTL could fire a small SCR to pop > the trigger transformer.
On Tue, 8 Sep 2015 08:40:29 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

>On Monday, September 7, 2015 at 8:26:45 PM UTC-4, John Larkin wrote: >> On Mon, 7 Sep 2015 20:20:14 -0400, bitrex >> <bitrex@de.lete.earthlink.net> wrote: >> >> >I got several of these xenon flash tubes down at Rat Shack on sale for >> >less than 2 bucks each. >> > >> >http://www.radioshack.com/long-life-xenon-strobe-tube/2721145.html >> > >> >Anyone have a design for a junk box circuit that could be used for >> >experimenting with these, say firing them from a TTL logic output? >> >> Well, you apply 300 volts across the end leads, with electrolytic caps >> to store as many joules as you think it can stand; that's not >> specified. Wild guess might be 30ish. > >We used to use one in a strobe. >Big yellow cap from Sprague.. 5 uF, 400 V.
That's only 0.4 joules, which is OK for a stroboscope but wimpy as a photoflash. A stroboscope is limited by average heating of the flashtube, whereas a photoflash is limited by exploding it in one zap. 300 joules is a pretty big flash, typical for a pro flash with a big spiral flashtube.
Den tirsdag den 8. september 2015 kl. 18.00.20 UTC+2 skrev John Larkin:
> On Tue, 8 Sep 2015 08:40:29 -0700 (PDT), George Herold > <gherold@teachspin.com> wrote: > > >On Monday, September 7, 2015 at 8:26:45 PM UTC-4, John Larkin wrote: > >> On Mon, 7 Sep 2015 20:20:14 -0400, bitrex > >> <bitrex@de.lete.earthlink.net> wrote: > >> > >> >I got several of these xenon flash tubes down at Rat Shack on sale for > >> >less than 2 bucks each. > >> > > >> >http://www.radioshack.com/long-life-xenon-strobe-tube/2721145.html > >> > > >> >Anyone have a design for a junk box circuit that could be used for > >> >experimenting with these, say firing them from a TTL logic output? > >> > >> Well, you apply 300 volts across the end leads, with electrolytic caps > >> to store as many joules as you think it can stand; that's not > >> specified. Wild guess might be 30ish. > > > >We used to use one in a strobe. > >Big yellow cap from Sprague.. 5 uF, 400 V. > > That's only 0.4 joules, which is OK for a stroboscope but wimpy as a > photoflash. A stroboscope is limited by average heating of the > flashtube, whereas a photoflash is limited by exploding it in one zap. > > 300 joules is a pretty big flash, typical for a pro flash with a big > spiral flashtube.
here's a 4800J one: https://youtu.be/tfUkDCVqw1I -Lasse
On Tue, 8 Sep 2015 09:32:14 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

>Den tirsdag den 8. september 2015 kl. 18.00.20 UTC+2 skrev John Larkin: >> On Tue, 8 Sep 2015 08:40:29 -0700 (PDT), George Herold >> <gherold@teachspin.com> wrote: >> >> >On Monday, September 7, 2015 at 8:26:45 PM UTC-4, John Larkin wrote: >> >> On Mon, 7 Sep 2015 20:20:14 -0400, bitrex >> >> <bitrex@de.lete.earthlink.net> wrote: >> >> >> >> >I got several of these xenon flash tubes down at Rat Shack on sale for >> >> >less than 2 bucks each. >> >> > >> >> >http://www.radioshack.com/long-life-xenon-strobe-tube/2721145.html >> >> > >> >> >Anyone have a design for a junk box circuit that could be used for >> >> >experimenting with these, say firing them from a TTL logic output? >> >> >> >> Well, you apply 300 volts across the end leads, with electrolytic caps >> >> to store as many joules as you think it can stand; that's not >> >> specified. Wild guess might be 30ish. >> > >> >We used to use one in a strobe. >> >Big yellow cap from Sprague.. 5 uF, 400 V. >> >> That's only 0.4 joules, which is OK for a stroboscope but wimpy as a >> photoflash. A stroboscope is limited by average heating of the >> flashtube, whereas a photoflash is limited by exploding it in one zap. >> >> 300 joules is a pretty big flash, typical for a pro flash with a big >> spiral flashtube. > >here's a 4800J one: https://youtu.be/tfUkDCVqw1I > >-Lasse
Try this: Get dark adapted and look down at a scene, some objects and maybe a newspaper, pretty close. Blast that with a couple hundred joules of flash, close up. The afterimages are astonishing.
"John Larkin" <jjlarkin@highlandtechnology.com> wrote in message 
news:av3uua5ih3dgf59urhs68gje0k0c1it5jc@4ax.com...
> On Tue, 8 Sep 2015 09:32:14 -0700 (PDT), Lasse Langwadt Christensen > <langwadt@fonz.dk> wrote: > >>Den tirsdag den 8. september 2015 kl. 18.00.20 UTC+2 skrev John Larkin: >>> On Tue, 8 Sep 2015 08:40:29 -0700 (PDT), George Herold >>> <gherold@teachspin.com> wrote: >>> >>> >On Monday, September 7, 2015 at 8:26:45 PM UTC-4, John Larkin wrote: >>> >> On Mon, 7 Sep 2015 20:20:14 -0400, bitrex >>> >> <bitrex@de.lete.earthlink.net> wrote: >>> >> >>> >> >I got several of these xenon flash tubes down at Rat Shack on sale >>> >> >for >>> >> >less than 2 bucks each. >>> >> > >>> >> >http://www.radioshack.com/long-life-xenon-strobe-tube/2721145.html >>> >> > >>> >> >Anyone have a design for a junk box circuit that could be used for >>> >> >experimenting with these, say firing them from a TTL logic output? >>> >> >>> >> Well, you apply 300 volts across the end leads, with electrolytic >>> >> caps >>> >> to store as many joules as you think it can stand; that's not >>> >> specified. Wild guess might be 30ish. >>> > >>> >We used to use one in a strobe. >>> >Big yellow cap from Sprague.. 5 uF, 400 V. >>> >>> That's only 0.4 joules, which is OK for a stroboscope but wimpy as a >>> photoflash. A stroboscope is limited by average heating of the >>> flashtube, whereas a photoflash is limited by exploding it in one zap. >>> >>> 300 joules is a pretty big flash, typical for a pro flash with a big >>> spiral flashtube. >> >>here's a 4800J one: https://youtu.be/tfUkDCVqw1I >> >>-Lasse > > Try this: > > Get dark adapted and look down at a scene, some objects and maybe a > newspaper, pretty close. Blast that with a couple hundred joules of > flash, close up. The afterimages are astonishing. > >
I don't know, is that a good idea? Your pupils are wide open and you hit the eyes with a very bright light. Maybe Dr. Hobbs can comment.
On Tue, 8 Sep 2015 09:32:14 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> Gave us:

>Den tirsdag den 8. september 2015 kl. 18.00.20 UTC+2 skrev John Larkin: >> On Tue, 8 Sep 2015 08:40:29 -0700 (PDT), George Herold >> <gherold@teachspin.com> wrote: >> >> >On Monday, September 7, 2015 at 8:26:45 PM UTC-4, John Larkin wrote: >> >> On Mon, 7 Sep 2015 20:20:14 -0400, bitrex >> >> <bitrex@de.lete.earthlink.net> wrote: >> >> >> >> >I got several of these xenon flash tubes down at Rat Shack on sale for >> >> >less than 2 bucks each. >> >> > >> >> >http://www.radioshack.com/long-life-xenon-strobe-tube/2721145.html >> >> > >> >> >Anyone have a design for a junk box circuit that could be used for >> >> >experimenting with these, say firing them from a TTL logic output? >> >> >> >> Well, you apply 300 volts across the end leads, with electrolytic caps >> >> to store as many joules as you think it can stand; that's not >> >> specified. Wild guess might be 30ish. >> > >> >We used to use one in a strobe. >> >Big yellow cap from Sprague.. 5 uF, 400 V. >> >> That's only 0.4 joules, which is OK for a stroboscope but wimpy as a >> photoflash. A stroboscope is limited by average heating of the >> flashtube, whereas a photoflash is limited by exploding it in one zap. >> >> 300 joules is a pretty big flash, typical for a pro flash with a big >> spiral flashtube. > >here's a 4800J one: https://youtu.be/tfUkDCVqw1I > >-Lasse
Here's another... bigger.... WAY bigger... https://www.youtube.com/watch?v=5sPjzWqSb2U
On Tue, 08 Sep 2015 09:44:51 -0700, John Larkin
<jjlarkin@highlandtechnology.com> Gave us:

>On Tue, 8 Sep 2015 09:32:14 -0700 (PDT), Lasse Langwadt Christensen ><langwadt@fonz.dk> wrote: > >>Den tirsdag den 8. september 2015 kl. 18.00.20 UTC+2 skrev John Larkin: >>> On Tue, 8 Sep 2015 08:40:29 -0700 (PDT), George Herold >>> <gherold@teachspin.com> wrote: >>> >>> >On Monday, September 7, 2015 at 8:26:45 PM UTC-4, John Larkin wrote: >>> >> On Mon, 7 Sep 2015 20:20:14 -0400, bitrex >>> >> <bitrex@de.lete.earthlink.net> wrote: >>> >> >>> >> >I got several of these xenon flash tubes down at Rat Shack on sale for >>> >> >less than 2 bucks each. >>> >> > >>> >> >http://www.radioshack.com/long-life-xenon-strobe-tube/2721145.html >>> >> > >>> >> >Anyone have a design for a junk box circuit that could be used for >>> >> >experimenting with these, say firing them from a TTL logic output? >>> >> >>> >> Well, you apply 300 volts across the end leads, with electrolytic caps >>> >> to store as many joules as you think it can stand; that's not >>> >> specified. Wild guess might be 30ish. >>> > >>> >We used to use one in a strobe. >>> >Big yellow cap from Sprague.. 5 uF, 400 V. >>> >>> That's only 0.4 joules, which is OK for a stroboscope but wimpy as a >>> photoflash. A stroboscope is limited by average heating of the >>> flashtube, whereas a photoflash is limited by exploding it in one zap. >>> >>> 300 joules is a pretty big flash, typical for a pro flash with a big >>> spiral flashtube. >> >>here's a 4800J one: https://youtu.be/tfUkDCVqw1I >> >>-Lasse > >Try this: > >Get dark adapted and look down at a scene, some objects and maybe a >newspaper, pretty close. Blast that with a couple hundred joules of >flash, close up. The afterimages are astonishing. >
Stare at this one then close your eyes. https://www.youtube.com/watch?v=_FB-zEg34oA What do you see?
On Tuesday, September 8, 2015 at 12:49:27 PM UTC-4, Tom Miller wrote:
> "John Larkin" <jjlarkin@highlandtechnology.com> wrote in message > news:av3uua5ih3dgf59urhs68gje0k0c1it5jc@4ax.com... > > On Tue, 8 Sep 2015 09:32:14 -0700 (PDT), Lasse Langwadt Christensen > > <langwadt@fonz.dk> wrote: > > > >>Den tirsdag den 8. september 2015 kl. 18.00.20 UTC+2 skrev John Larkin: > >>> On Tue, 8 Sep 2015 08:40:29 -0700 (PDT), George Herold > >>> <gherold@teachspin.com> wrote: > >>> > >>> >On Monday, September 7, 2015 at 8:26:45 PM UTC-4, John Larkin wrote: > >>> >> On Mon, 7 Sep 2015 20:20:14 -0400, bitrex > >>> >> <bitrex@de.lete.earthlink.net> wrote: > >>> >> > >>> >> >I got several of these xenon flash tubes down at Rat Shack on sale > >>> >> >for > >>> >> >less than 2 bucks each. > >>> >> > > >>> >> >http://www.radioshack.com/long-life-xenon-strobe-tube/2721145.html > >>> >> > > >>> >> >Anyone have a design for a junk box circuit that could be used for > >>> >> >experimenting with these, say firing them from a TTL logic output? > >>> >> > >>> >> Well, you apply 300 volts across the end leads, with electrolytic > >>> >> caps > >>> >> to store as many joules as you think it can stand; that's not > >>> >> specified. Wild guess might be 30ish. > >>> > > >>> >We used to use one in a strobe. > >>> >Big yellow cap from Sprague.. 5 uF, 400 V. > >>> > >>> That's only 0.4 joules, which is OK for a stroboscope but wimpy as a > >>> photoflash. A stroboscope is limited by average heating of the > >>> flashtube, whereas a photoflash is limited by exploding it in one zap. > >>> > >>> 300 joules is a pretty big flash, typical for a pro flash with a big > >>> spiral flashtube. > >> > >>here's a 4800J one: https://youtu.be/tfUkDCVqw1I > >> > >>-Lasse > > > > Try this: > > > > Get dark adapted and look down at a scene, some objects and maybe a > > newspaper, pretty close. Blast that with a couple hundred joules of > > flash, close up. The afterimages are astonishing. > > > > > > I don't know, is that a good idea? Your pupils are wide open and you hit the > eyes with a very bright light. Maybe Dr. Hobbs can comment.
Oh fun... let's try and guess some numbers. So I think the eye can take 1mW with the blink reflex. (That is, if you look at the sun you get about 1 mW, but then blink and close your eyes..) I'm not sure how long it takes to blink, is 100ms too long? So (maybe) 0.1 Joules into the eye. So you flash 100 Joules onto a piece of paper.. how much goes into your eye? (I'll not worry about reflectivity of the paper... maybe it's 30-50%... but that goes into JL's few hundred Joules.) And then a ratio of the area's say 12" square for the paper (300mm) and 5mm diameter for the eye. A ratio of 60 in length or 3600 in area so ~0.03 Joules into the eye. (OK a lot of assumptions in just taking the area ratio...) I guess I might give it a try. Does it hurt your eyes when you do it John? George H.