Forums

Xenon flash tube

Started by bitrex September 7, 2015
On Mon, 07 Sep 2015 20:39:00 -0400, Tom Miller wrote:

> "bitrex" <bitrex@de.lete.earthlink.net> wrote in message > news:55ee2b1c$0$17143$4c5ecfc7@frugalusenet.com... >> On 9/7/2015 8:20 PM, 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? >> >> I guess this works but I don't have anything like that trigger >> transformer in stock... >> >> http://www.bristolwatch.com/ele/ > > Find a store that processes the disposable film cameras and see if they > will give you a few. The ones with the built in flash will have > everything but the SCR. Most times they are free for the taking.
AFAIK they have the SCR as well. My kid has a bag of 'em, from an abortive project to build a rail gun. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
On Tuesday, September 8, 2015 at 1:25:32 PM UTC-4, Tim Wescott wrote:
> On Mon, 07 Sep 2015 20:39:00 -0400, Tom Miller wrote: > > > "bitrex" <bitrex@de.lete.earthlink.net> wrote in message > > news:55ee2b1c$0$17143$4c5ecfc7@frugalusenet.com... > >> On 9/7/2015 8:20 PM, 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? > >> > >> I guess this works but I don't have anything like that trigger > >> transformer in stock... > >> > >> http://www.bristolwatch.com/ele/ > > > > Find a store that processes the disposable film cameras and see if they > > will give you a few. The ones with the built in flash will have > > everything but the SCR. Most times they are free for the taking. > > AFAIK they have the SCR as well. My kid has a bag of 'em, from an > abortive project to build a rail gun. > > -- > > Tim Wescott > Wescott Design Services > http://www.wescottdesign.com
Re Rail gun: This from the thread about pain vs frequency. (well from that guys site... kinda a hoot.) http://www.electroboom.com/?p=101 George H.
On Tue, 8 Sep 2015 10:24:54 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

>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. >
I never noticed any pain or aftereffects, once the afterimages faded, in a minute maybe. There is an initial bright, very sharp and spooky image, which transitions to a negative image, which then fades away. A serious eye exam seems much more intense to me than this flash trick. A retina exam can be painful and leave me seeing purple for some minutes.
On 9/7/2015 7:20 PM, 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?
Not sure what good it is, but I saw a video where a guy fire of a tube with a piezo electric unit from a propane stove. Mikek
On Tuesday, September 8, 2015 at 1:42:42 PM UTC-4, John Larkin wrote:
> On Tue, 8 Sep 2015 10:24:54 -0700 (PDT), George Herold > <gherold@teachspin.com> wrote: > > >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. > > > > I never noticed any pain or aftereffects, once the afterimages faded, > in a minute maybe. There is an initial bright, very sharp and spooky > image, which transitions to a negative image, which then fades away. > > A serious eye exam seems much more intense to me than this flash > trick. A retina exam can be painful and leave me seeing purple for > some minutes.
I made a math mistake... 1 mW * 0.1s = 0.1 mJ not 0.1 J. George H.
On Tue, 8 Sep 2015 13:33:02 -0500, amdx <nojunk@knology.net> wrote:

>On 9/7/2015 7:20 PM, 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? > > > Not sure what good it is, but I saw a video where a guy fire of a >tube with a piezo electric unit from a propane stove. > Mikek
That should work. You can also just ramp up the voltage until the tube fires on its own, at some kilovolts. I bet an optical input, like a pulse from a blue or UV LED, could fire a flashtube too, probably at a pretty high voltage, close to the natural breakdown.
On 9/8/2015 2:30 PM, John Larkin wrote:
> On Tue, 8 Sep 2015 13:33:02 -0500, amdx <nojunk@knology.net> wrote: > >> On 9/7/2015 7:20 PM, 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? >> >> >> Not sure what good it is, but I saw a video where a guy fire of a >> tube with a piezo electric unit from a propane stove. >> Mikek > > That should work. You can also just ramp up the voltage until the tube > fires on its own, at some kilovolts. > > I bet an optical input, like a pulse from a blue or UV LED, could fire > a flashtube too, probably at a pretty high voltage, close to the > natural breakdown. > > > >
15 years ago I tried triggering one flashtube with the flash of another one. I never got it to work. I didn't try increasing the voltage. Mikek
On 9/8/2015 9:53 AM, Joe Gwinn wrote:
> 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 >
Good to know, thanks!
On Tuesday, September 8, 2015 at 1:33:20 PM UTC-7, amdx wrote:

> 15 years ago I tried triggering one flashtube with the flash of > another one. I never got it to work. I didn't try increasing the voltage.
It needs UV illumination of the cathode. Either UV filtering in the tube(s), or poor focusing of the illumination onto the target electrode will defeat the effect. If the 'target' electrode is shaded, behind the reflector of the flash, that'd explain the difficulty. Photothrystors are actually kind of interesting gadgets.
Electronic Goldmine Surplus sells common strobe parts at the right prices...
You might start there.

You can trigger many ways, a pulse of HV on the external trigger electrode, or series injection triggering, using a transformer in series or a blocking diode to insert a trigger voltage.  Even HV DC will trigger it. 

 Without the trigger pulse it takes 1000-1700 VDC from Anode to Cathode to break down one of the U shaped tubes. 

This is good reading for the serious technophile:

http://laser-caltech.web.cern.ch/laser-caltech/report/Flash%20lamp%20Eg&G.pdf

About 15$ at Autozone gets you the classic car or tractor ignition coil, which works just fine as an external trigger. 

Usually I use an  MOC series opto-triac in a six pin package to push charge into the trigger SCR gate lead from a 0.1uf cap via a 100 ohm resistor. 
Charging current for the trigger cap comes via a large enough resistor that the SCR is starved below its holding current. I'm using half the Triac as an SCR. 

If I'm not doing that, I use a 555 wired as an inverting driver and push the gate with 100 ohms off pin 3 of the 555.

If you can find a SGR20N40L or similar IGBT, this app-note lets you "Quench" the strobe by cutting off the current, and the same IGBT triggers the tube that cuts it off. That can be very useful for high speed photography, but I'd start 
with normal triggering.

https://www.fairchildsemi.com/application-notes/AN/AN-9006.pdf

Steve 
 


Steve