Chip with simple program for Toy

Solar Products Manufacturer

Unitop Power Electronics Pvt Ltd, is delighted to introduce itself as a noticeable Manufacturer and Exporter of huge range of UPS, UPS and Servo Stabilizers. Power Protection and Power Backup Systems. Our product line encompasses Voltage Stabilizer, Online Ups, Solar Power, Power Protection System and many more.
http://www.unitoppower.com/about-us.html

 

[Michael A. Terrell]

George Herold wrote:

I'm thinking that a shematic has diodes that 'go both ways'.
And maybe some genderless connectors.

That spammer you replied to posted to a thread that's been dead since
1999.

 

[George Herold]

I'm thinking that a shematic has diodes that 'go both ways'.
And maybe some genderless connectors.

George H.

 

[Michael Black]

On Fri, 21 Jun 2013, Michael A. Terrell wrote:

George Herold wrote:

I'm thinking that a shematic has diodes that 'go both ways'.
And maybe some genderless connectors.

That spammer you replied to posted to a thread that's been dead since
1999.

And most of the time, the giveaway is not a date, but because the reply

comes out of nowhere, the rest of the thread isn't there.

It's not 1994 or so, when it wasn't uncommon for messages to get lost, or
take their time arriving. I can remember that time when replies would
arrive before the original post, and sometimes messages just got lost
along they way, the only way to know about them was when someone replied
to them.

But that's long in the past. The only time I see replies where I've not
seen the original post is the people using google who reply to old
messages.

Michael

 

[Jon Kirwan]

On Wed, 17 Jul 2013 15:40:30 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:

On Wed, 17 Jul 2013 09:51:54 -0700, Jon Kirwan
jonk@infinitefactors.org> wrote:

On Tue, 16 Jul 2013 19:26:09 -0700, I wrote:

On Tue, 16 Jul 2013 17:45:33 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

snip
This is sci.electronics.BASICS after all.
snip

Speaking of which, any thoughts on this issue:

By the way, right now I'm struggling with the idea of how to
actively enable individual half-current mirror BJTs in such a
way that I can selectively enable various combinations of
these extended mirror sections without impacting others which
remain "on." I'm already including emitter degeneration of 1
Ohm (or 100mV at 100mA), which improves significantly in
dealing with variations in Is and temperature variations with
each BJT. And it works fine on a protoboard, so I'm liking
that result. But if one of the BJTs has no load (infinite
resistance in effect), it saturates like crazy and messes
with the other BJTs. (And the degree of that problem gets
worse with emitter degeneration, too.) So I need a cheap and
easy way (I'm coming up with HORRIBLY EXPENSIVE and HARD ways
I don't want to use) to be able to selectively activate an
opposing switch (current source/sink on one side that is
under active control and a BJT switch on the other side which
selectively permits or blocks the programmed current.)

I'm just not seeing a simple way. It's all way too hairy for
my liking. (Can easily see how it might be approached with
MOSFETs, for example, but I get BJTs at better than 2 for a
penny and I get MOSFETs for a LOT MORE than that, even when
on sale.) I'm looking for a BJT and discrete (I can't do
designs with equal emitter areas on common subtrates, for
example, and I can't afford to throw dozens of BJTs at
everything either because I'm not doing an ASIC.)

Fun problem.

I would plan to design the power supply to provide about 1.5V
of headroom beyond what is needed by the LEDs at peak current
drive. That should provide a good 1.2V for the current mirror
side of things and 0.3V for the switch on the other end. (If
it can be done with less headroom, so much the better.)

The issue is this:

To have a controlled current sink (or source) capable of
supporting ... let's say at least 8 sinks/sources ... and
where each sink/source can be individually enabled or
disabled without affecting any of the others. Only BJTs as
active devices. Only discretes, no ICs, no opamps, etc.

My imagination fails me for a reasonable solution here. How
about yours?

Here's the best I can do with my meager imagination, John.
This achieves my goals, but it takes 5 BJTs per section, plus
2 more BJTs for all sections. So the number of BJTs equals
5*N+2, where N is the number of individually controllable
current strings.

It doesn't use a common current setting method, though. Each
string is set individually through R1 (combined with the base
drive voltage at Q1.) So I'd like to improve that detail, as
well.

The example uses 6V for the LED supply and assumes 3.6V for
the microcontroller Vcc for illustration purposes. It also
uses two LEDs in a series chain, also for illustration
purposes.

: ,------ to other sections
: |
: |
: +6 +6 | +6
: | | | |
: | | | |
: | | | |
: | | | |
: |<e Q3 Q5 e>| | |<e Q6
: ,------------------| 2N3906 |-----+---+---| 2N3906
: | |\c c/| | |\c
: | | 2N3906 | | |
: | +6 | | | |
: | | | | | |
: | | | | | |
: | | | | Q7 e>| |
: | \ ,---------------+ 2N3906 |---+
: | R4 / | | | c/| |
: | 1k \ | | | | |
: | / | --- | | |
: | | | \ / D2 \ | |
: | | | --- LED R3 / | \
: | | | | 2.7k \ | / R4
: | | | | / gnd \ 5.6k
: | | | | | /
: |/c Q1 Q2 c\| | | | |
: Micro I/O ---| 2N3904 |---' --- | |
: |>e e<| \ / D1 | |
: | 2N3904 | --- LED | gnd
: | | | |
: '-----+-----' | |<e Q4
: | +----------| 2N3906
: | | |\c
: \ | |
: / R2 | |
: \ 2.7k \ |
: / / R1 |
: | \ 2.7 gnd
: | /
: | |
: gnd |
: |
: gnd

It's basically a diff-amp driven through a level shifter.

I'd love to see creative improvements (WITHOUT OPAMPS OR
MOSFETS.)

Jon

My R2 above provides way too much gain. Should be a lot
smaller -- orders of magnitude.

No mosfets even?

https://dl.dropboxusercontent.com/u/53724080/Circuits/Current_Sources/LED_Regs.JPG

No mosfets. I'm not fighting in that jungle, yet. I might
start if you know where I can get them for 2 for a penny in
10000 qty. (I give stuff away to kids and don't mind spending
$50 to $100 for stuff I will simply give away to anyone
interested.)

Jon

 

[John Fields]

On Wed, 17 Jul 2013 15:40:30 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:

On Wed, 17 Jul 2013 09:51:54 -0700, Jon Kirwan
jonk@infinitefactors.org> wrote:

I'd love to see creative improvements (WITHOUT OPAMPS OR
MOSFETS.)

Jon


No mosfets even?

---
Didn't he say: "WITHOUT OPAMPS OR MOSFETS."?

--
JF

 

[Jon Kirwan]

On Wed, 17 Jul 2013 15:40:30 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:

https://dl.dropboxusercontent.com/u/53724080/Circuits/Current_Sources/LED_Regs.JPG

So I just decided to take a look (besides seeing the mosfet.)

Looking at schematic A: I see a diff-amp with 0.2V input (I
suppose you would tell me to use a R-divider if I were being
cheap about this.) One of its collectors (let's call that PNP
Q1 for now) collector is used to pull up on the base of
another NPN (call it Q2 for now) that ties the mosfet gate.
To get the voltage at the base of Q2 high enough that it is
slightly or usefully active, the collector of Q1 must reach
near to 0.65V or so. But the base is 0.2V. You see any
problem here? I guess you offered as much thought as you felt
I deserved.

Jon

 

[Oppie]

Sorry I missed the beginning of the thread. Just jumping in here...
I believe that the operating term here is Ferroresonant voltage stabilizer.
Sola Electric www.solahevidutysales.com was one of the big players 30 or so
years ago before UPS systems became mainstream. They were grossly
inefficient and had lousy power factors but did protect computer systems
fairly well from dips and spikes.

<unitoppowers@gmail.com> wrote in message
news:b786c8c4-53ed-46e3-b23a-0b6d7de20fa2@googlegroups.com...

Solar Products Manufacturer

Unitop Power Electronics Pvt Ltd, is delighted to introduce itself as a
noticeable Manufacturer and Exporter of huge range of UPS, UPS and Servo
Stabilizers. Power Protection and Power Backup Systems. Our product line
encompasses Voltage Stabilizer, Online Ups, Solar Power, Power Protection
System and many more.
http://www.unitoppower.com/about-us.html

 

[Oppie]

Oops

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:N_adnVfnv8o7-1nMnZ2dnUVZ_qiXnZ2d@earthlink.com...

George Herold wrote:

I'm thinking that a shematic has diodes that 'go both ways'.
And maybe some genderless connectors.

That spammer you replied to posted to a thread that's been dead since
1999.

 

[Michael Black]

On Mon, 22 Jul 2013, Oppie wrote:

Sorry I missed the beginning of the thread. Just jumping in here...
I believe that the operating term here is Ferroresonant voltage stabilizer.
Sola Electric www.solahevidutysales.com was one of the big players 30 or so
years ago before UPS systems became mainstream. They were grossly inefficient
and had lousy power factors but did protect computer systems fairly well from
dips and spikes.

If you don't see the start of the thread, check google. Chances are that

you didn't see the first post because it is old, and some idiot is
replying to a really old post.

This isn't the old days when messages were passed over phone lines, or
many had access only via computer BBSs, where replies often could arrive
before the original, and some messages never arrived, a less than reliable
system. Now that the major backbone of Usenet is the internet (phone
lines only used for a relative handful of sites that have no internet
access, if those still exist), it's been a long time since I noticed
missed messages.

Michael

unitoppowers@gmail.com> wrote in message
news:b786c8c4-53ed-46e3-b23a-0b6d7de20fa2@googlegroups.com...
Solar Products Manufacturer

Unitop Power Electronics Pvt Ltd, is delighted to introduce itself as a
noticeable Manufacturer and Exporter of huge range of UPS, UPS and Servo
Stabilizers. Power Protection and Power Backup Systems. Our product line
encompasses Voltage Stabilizer, Online Ups, Solar Power, Power Protection
System and many more.
http://www.unitoppower.com/about-us.html

 

On Mon, 22 Jul 2013 16:25:21 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Mon, 22 Jul 2013 18:56:25 -0400, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

On Sun, 21 Jul 2013 18:20:16 -0700, the renowned Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

We have a 12 year old granddaughter visiting for the month of July.

Pretty good kid, except for a severe case of Jewish Princess
(literally ;-)

She's got this iPad (whatever) and she convinced me to add a wireless
router (which I would otherwise have absolutely no use for

Any way for me to automate it quitting about 9PM at night until 9 the
following morning.

I know I can just unplug it, which she'll notice. So I'm looking for
some program which would "do the deed" >:-}

...Jim Thompson


You should be able to set it on your main router to block WAN access
by the wireless router.

Mine has a feature called schedules..

Schedules:
List of Available Schedules

Schedules define the timeframes under which firewall rules may be
applied.

Name: Name of the schedule for identification and management purposes
Days: The days when the schedule is active.
Start Time: The start time for the schedule
End Time: The end time for the schedule.
The actions that can be taken on schedules are:
(Check Box At First Column Header): Selects all the schedules in the
table.
Edit: Opens the Schedule Configuration page, to edit the selected
schedule.

It's flexible enough to set different times on different days of the
week and that sort of thing.

I also set up the NNTP server so the router always knows the correct
time.

The older router that this one just replaced (an ancient DI604) had a
similar feature without the indirection of using a schedule (you just
set the time frame for each rule within the rule).



Best regards,
Spehro Pefhany

The Medialink has a time-based blocking feature. But the
granddaughter and I have come to "agreement" >:-}

...Jim Thompson
Perfect. Much better to be honest and up front. Our kids respect

honesty.
Eric

 

[Jim Thompson]

On Tue, 23 Jul 2013 11:24:36 -0700, etpm@whidbey.com wrote:

On Mon, 22 Jul 2013 16:25:21 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Mon, 22 Jul 2013 18:56:25 -0400, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

On Sun, 21 Jul 2013 18:20:16 -0700, the renowned Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

We have a 12 year old granddaughter visiting for the month of July.

Pretty good kid, except for a severe case of Jewish Princess
(literally ;-)

She's got this iPad (whatever) and she convinced me to add a wireless
router (which I would otherwise have absolutely no use for

Any way for me to automate it quitting about 9PM at night until 9 the
following morning.

I know I can just unplug it, which she'll notice. So I'm looking for
some program which would "do the deed" >:-}

...Jim Thompson


You should be able to set it on your main router to block WAN access
by the wireless router.

Mine has a feature called schedules..

Schedules:
List of Available Schedules

Schedules define the timeframes under which firewall rules may be
applied.

Name: Name of the schedule for identification and management purposes
Days: The days when the schedule is active.
Start Time: The start time for the schedule
End Time: The end time for the schedule.
The actions that can be taken on schedules are:
(Check Box At First Column Header): Selects all the schedules in the
table.
Edit: Opens the Schedule Configuration page, to edit the selected
schedule.

It's flexible enough to set different times on different days of the
week and that sort of thing.

I also set up the NNTP server so the router always knows the correct
time.

The older router that this one just replaced (an ancient DI604) had a
similar feature without the indirection of using a schedule (you just
set the time frame for each rule within the rule).



Best regards,
Spehro Pefhany

The Medialink has a time-based blocking feature. But the
granddaughter and I have come to "agreement" >:-}

...Jim Thompson
Perfect. Much better to be honest and up front. Our kids respect
honesty.
Eric

Yup. Rule-based honesty always works best.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

On Tue, 23 Jul 2013 11:51:17 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 23 Jul 2013 11:24:36 -0700, etpm@whidbey.com wrote:

On Mon, 22 Jul 2013 16:25:21 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Mon, 22 Jul 2013 18:56:25 -0400, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

On Sun, 21 Jul 2013 18:20:16 -0700, the renowned Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

We have a 12 year old granddaughter visiting for the month of July.

Pretty good kid, except for a severe case of Jewish Princess
(literally ;-)

She's got this iPad (whatever) and she convinced me to add a wireless
router (which I would otherwise have absolutely no use for

Any way for me to automate it quitting about 9PM at night until 9 the
following morning.

I know I can just unplug it, which she'll notice. So I'm looking for
some program which would "do the deed" >:-}

...Jim Thompson


You should be able to set it on your main router to block WAN access
by the wireless router.

Mine has a feature called schedules..

Schedules:
List of Available Schedules

Schedules define the timeframes under which firewall rules may be
applied.

Name: Name of the schedule for identification and management purposes
Days: The days when the schedule is active.
Start Time: The start time for the schedule
End Time: The end time for the schedule.
The actions that can be taken on schedules are:
(Check Box At First Column Header): Selects all the schedules in the
table.
Edit: Opens the Schedule Configuration page, to edit the selected
schedule.

It's flexible enough to set different times on different days of the
week and that sort of thing.

I also set up the NNTP server so the router always knows the correct
time.

The older router that this one just replaced (an ancient DI604) had a
similar feature without the indirection of using a schedule (you just
set the time frame for each rule within the rule).



Best regards,
Spehro Pefhany

The Medialink has a time-based blocking feature. But the
granddaughter and I have come to "agreement" >:-}

...Jim Thompson
Perfect. Much better to be honest and up front. Our kids respect
honesty.
Eric

Yup. Rule-based honesty always works best.

...Jim Thompson
I dunno if it has to be rule based, but if you make a rule, and are

honest about the reasons, even if they are arbitrary, the rules are
much easier to follow. Much better than saying"The machine just won't
let you connect at night, I don't know why". I'm not implying your
rules are arbitrary though.
Eric

 

[Tim Wescott]

On Fri, 02 Aug 2013 19:43:18 -0700, sagephotoworld wrote:

OK.

I want to build a lower-power LED microflash. You're probably familiar
with Edgerton's microflash that produced a 1/1,000,000 second flash by
arcing 50,000v across an air gap that had been ionized by 25,000v and is
commonly used to photograph bullets in flight?

The fastest flash available from xenon tubes is 1/110,000 second and a
flash such as a Canon 580EX2 runs at a maximum of 1/38.000th second.

What I want to do is to build an LED version of a flash since LEDs
though lower in power, will pulse very quickly. I'm not planning to
build the ultimate LED microflash. I have an LED light panel that I
built with about 170 white LEDs in parallel. That runs happily off 2 x C
cells.

If I could pulse light from those LEDs at 1/50,000th second I would be
happy. If I could get down to 1/100,000 second I would be ecstatic.

I realise it probably wouldn't be very bright and that I might well have
to crank my ISO upto 1600 but I'd like to have a go and play with it;
maybe try it with different LEDs and different voltages later.

I don't want to use any ICs in the circuit because they tend to
introduce both complications and possible frequency problems. For
example, in 1/38,000th of a second, a .177 airgun pellet travelling at
500 feet per seond will travel 0.17 of an inch. That might not seem much
but when you're taking photos from 3 - 4 feet away, it's quite a
distance. It leaves a blur of approximately the length of the pellet or
rather doubles the length of a blurry pellet.

The following image (if it posts) is of a blurry pellet after it has
been slowed by impacting a razor blade. The exposure was 1/38,000th.

I want to try to do this kindof thing with LEDs or at least to try it
and at least have some fun attempting it.

img src =
"https://lh4.googleusercontent.com/-1hNyjojhl3A/Tsfwn6O48II/AAAAAAAAB2E/
wyXqy7HpmSw/w798-h532-no/photo7.jpg"

You're going to have some serious difficulties, and your attempt to keep
it simple by keeping the IC's out of it will probably either complicate
things, or make your job impossible.

Diodes tend to be constant-voltage devices, which means that they 'want'
to be driven with a constant (or at least fairly constant) current
source. So wiring a bunch of them in parallel is a problem, because
whichever ones happen to have a bit lower voltage naturally are going to
'steal' current from the naturally higher-voltage ones.

Diodes also have storage effects. Current flows in them because the
junction is saturated by carriers (both electrons and holes). If you
simply remove the current from a diode the carriers persist for a while.
In an LED, it's these carriers of opposite polarity falling into each
other that make the light glow -- so without external help, the light
will die out exponentially, and probably pretty slowly compared to
1/40000 second.

All in all, here's what I think you need to do:

1: put a resistor in series with each diode. It doesn't have to be much,
but it should probably drop one or two volts at your design current.

2: decide on a current for each diode (this is your design current). If
your diodes came from a reputable source, then they should be specified
for the maximum pulse current you can run through them. If not,
experiment. You can probably jam a lot more current through than the
maximum continuous current, which is limited by heat.

3: figure out how much current it adds up to. It'll be lots.

4: make a driver that'll drive at least 5 volts at that current, with a
rise time that's a fraction of your 1/40000th of a second. Good luck
doing that without IC's.

5: make the driver so that when you signal the end of a pulse it doesn't
just go to zero volts -- it should reverse polarity and apply -5V to all
the diodes, at least briefly. Expect lots of current to flow -- if you
go with 100mA per diode, that's 17A. If you can push each diode higher
-- that's more.

6: make a wiring harness such that the time constant of the effective
resistance of the panel combined with the inductance of the wiring is an
insignificant fraction of 1/40000 of a second. Soldering your LEDs onto
planes on a circuit board may do this, but you might need something with
closer spacing than the usual 1/16th inch.

etc. I've pretty much listed out the minimum requirements that I could
think of. I'm sure that there's more. This is not for the faint of
heart, or for people who are under the mistaken impression that not using
integrated circuits for such a difficult task will make their lives
easier.

--

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

 

[John Larkin]

On Fri, 2 Aug 2013 19:43:18 -0700 (PDT), sagephotoworld@gmail.com wrote:

OK.

I want to build a lower-power LED microflash. You're probably familiar with Edgerton's microflash that produced a 1/1,000,000 second flash by arcing 50,000v across an air gap that had been ionized by 25,000v and is commonly used to photograph bullets in flight?

The fastest flash available from xenon tubes is 1/110,000 second and a flash such as a Canon 580EX2 runs at a maximum of 1/38.000th second.

What I want to do is to build an LED version of a flash since LEDs though lower in power, will pulse very quickly. I'm not planning to build the ultimate LED microflash. I have an LED light panel that I built with about 170 white LEDs in parallel. That runs happily off 2 x C cells.

If I could pulse light from those LEDs at 1/50,000th second I would be happy. If I could get down to 1/100,000 second I would be ecstatic.

Doesn't sound hard. One gotcha is that a white LED is a blue LED with a
blue-to-yellow conversion phosphor. I don't know the response speed of the
phosphor. You might goodle that and make sure it's not a problem.

I realise it probably wouldn't be very bright and that I might well have to crank my ISO upto 1600 but I'd like to have a go and play with it; maybe try it with different LEDs and different voltages later.

I don't want to use any ICs in the circuit because they tend to introduce both complications and possible frequency problems. For example, in 1/38,000th of a second, a .177 airgun pellet travelling at 500 feet per seond will travel 0.17 of an inch. That might not seem much but when you're taking photos from 3 - 4 feet away, it's quite a distance. It leaves a blur of approximately the length of the pellet or rather doubles the length of a blurry pellet.

The following image (if it posts) is of a blurry pellet after it has been slowed by impacting a razor blade. The exposure was 1/38,000th.

I want to try to do this kindof thing with LEDs or at least to try it and at least have some fun attempting it.

img src = "https://lh4.googleusercontent.com/-1hNyjojhl3A/Tsfwn6O48II/AAAAAAAAB2E/wyXqy7HpmSw/w798-h532-no/photo7.jpg"

With no ICs, how would you sync the flash to some event?

Even a cheap disposal flash dumps 5 or so joules into its flashtube.

1 joule might be usable with a fast camera, up close. That's a million watts for
1 microsecond, say a million amps or so into the LED array. About 6000 amps per
LED.

We have a problem here.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

 

[Tim Wescott]

On Fri, 02 Aug 2013 21:16:59 -0700, John Larkin wrote:

On Fri, 2 Aug 2013 19:43:18 -0700 (PDT), sagephotoworld@gmail.com wrote:

OK.

I want to build a lower-power LED microflash. You're probably familiar
with Edgerton's microflash that produced a 1/1,000,000 second flash by
arcing 50,000v across an air gap that had been ionized by 25,000v and is
commonly used to photograph bullets in flight?

The fastest flash available from xenon tubes is 1/110,000 second and a
flash such as a Canon 580EX2 runs at a maximum of 1/38.000th second.

What I want to do is to build an LED version of a flash since LEDs
though lower in power, will pulse very quickly. I'm not planning to
build the ultimate LED microflash. I have an LED light panel that I
built with about 170 white LEDs in parallel. That runs happily off 2 x C
cells.

If I could pulse light from those LEDs at 1/50,000th second I would be
happy. If I could get down to 1/100,000 second I would be ecstatic.

Doesn't sound hard. One gotcha is that a white LED is a blue LED with a
blue-to-yellow conversion phosphor. I don't know the response speed of
the phosphor. You might goodle that and make sure it's not a problem.

And you can't speed up the phosphor with the "suck the current out of the

LED" trick.

I realise it probably wouldn't be very bright and that I might well have
to crank my ISO upto 1600 but I'd like to have a go and play with it;
maybe try it with different LEDs and different voltages later.

I don't want to use any ICs in the circuit because they tend to
introduce both complications and possible frequency problems. For
example, in 1/38,000th of a second, a .177 airgun pellet travelling at
500 feet per seond will travel 0.17 of an inch. That might not seem much
but when you're taking photos from 3 - 4 feet away, it's quite a
distance. It leaves a blur of approximately the length of the pellet or
rather doubles the length of a blurry pellet.

The following image (if it posts) is of a blurry pellet after it has
been slowed by impacting a razor blade. The exposure was 1/38,000th.

I want to try to do this kindof thing with LEDs or at least to try it
and at least have some fun attempting it.

img src =
"https://lh4.googleusercontent.com/-1hNyjojhl3A/Tsfwn6O48II/AAAAAAAAB2E/
wyXqy7HpmSw/w798-h532-no/photo7.jpg"

With no ICs, how would you sync the flash to some event?

Even a cheap disposal flash dumps 5 or so joules into its flashtube.

1 joule might be usable with a fast camera, up close. That's a million
watts for 1 microsecond, say a million amps or so into the LED array.
About 6000 amps per LED.

We have a problem here.

Lots of BB's, in multiple exposures, with everything carefully aligned
and timed.

Of course, this means you have to keep replacing razor blades.

--

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

 

[John Larkin]

On Fri, 02 Aug 2013 23:28:16 -0500, Tim Wescott <tim@seemywebsite.really> wrote:

On Fri, 02 Aug 2013 21:16:59 -0700, John Larkin wrote:

On Fri, 2 Aug 2013 19:43:18 -0700 (PDT), sagephotoworld@gmail.com wrote:

OK.

I want to build a lower-power LED microflash. You're probably familiar
with Edgerton's microflash that produced a 1/1,000,000 second flash by
arcing 50,000v across an air gap that had been ionized by 25,000v and is
commonly used to photograph bullets in flight?

The fastest flash available from xenon tubes is 1/110,000 second and a
flash such as a Canon 580EX2 runs at a maximum of 1/38.000th second.

What I want to do is to build an LED version of a flash since LEDs
though lower in power, will pulse very quickly. I'm not planning to
build the ultimate LED microflash. I have an LED light panel that I
built with about 170 white LEDs in parallel. That runs happily off 2 x C
cells.

If I could pulse light from those LEDs at 1/50,000th second I would be
happy. If I could get down to 1/100,000 second I would be ecstatic.

Doesn't sound hard. One gotcha is that a white LED is a blue LED with a
blue-to-yellow conversion phosphor. I don't know the response speed of
the phosphor. You might goodle that and make sure it's not a problem.

And you can't speed up the phosphor with the "suck the current out of the
LED" trick.

I realise it probably wouldn't be very bright and that I might well have
to crank my ISO upto 1600 but I'd like to have a go and play with it;
maybe try it with different LEDs and different voltages later.

I don't want to use any ICs in the circuit because they tend to
introduce both complications and possible frequency problems. For
example, in 1/38,000th of a second, a .177 airgun pellet travelling at
500 feet per seond will travel 0.17 of an inch. That might not seem much
but when you're taking photos from 3 - 4 feet away, it's quite a
distance. It leaves a blur of approximately the length of the pellet or
rather doubles the length of a blurry pellet.

The following image (if it posts) is of a blurry pellet after it has
been slowed by impacting a razor blade. The exposure was 1/38,000th.

I want to try to do this kindof thing with LEDs or at least to try it
and at least have some fun attempting it.

img src =
"https://lh4.googleusercontent.com/-1hNyjojhl3A/Tsfwn6O48II/AAAAAAAAB2E/
wyXqy7HpmSw/w798-h532-no/photo7.jpg"

With no ICs, how would you sync the flash to some event?

Even a cheap disposal flash dumps 5 or so joules into its flashtube.

1 joule might be usable with a fast camera, up close. That's a million
watts for 1 microsecond, say a million amps or so into the LED array.
About 6000 amps per LED.

We have a problem here.

Lots of BB's, in multiple exposures, with everything carefully aligned
and timed.

Equivalent-time shooting.

Of course, this means you have to keep replacing razor blades.

If you wrapped the LEDs around the razor blade target, all pointing right where
they need to, you might be able to get an image with way less than a joule. But
the numbers are still bad... 10 mJ is still 60 amps per LED, and they probably
don't work very well at 60 amps. And it sounds like the array is already
assembled in a flat sheet.

Spark gaps sound more sensible. They can be run at a megawatt.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

 

OK.

I want to build a lower-power LED microflash. You're probably familiar with Edgerton's microflash that produced a 1/1,000,000 second flash by arcing 50,000v across an air gap that had been ionized by 25,000v and is commonly used to photograph bullets in flight?

The fastest flash available from xenon tubes is 1/110,000 second and a flash such as a Canon 580EX2 runs at a maximum of 1/38.000th second.

What I want to do is to build an LED version of a flash since LEDs though lower in power, will pulse very quickly. I'm not planning to build the ultimate LED microflash. I have an LED light panel that I built with about 170 white LEDs in parallel. That runs happily off 2 x C cells.

If I could pulse light from those LEDs at 1/50,000th second I would be happy. If I could get down to 1/100,000 second I would be ecstatic.

I realise it probably wouldn't be very bright and that I might well have to crank my ISO upto 1600 but I'd like to have a go and play with it; maybe try it with different LEDs and different voltages later.

I don't want to use any ICs in the circuit because they tend to introduce both complications and possible frequency problems. For example, in 1/38,000th of a second, a .177 airgun pellet travelling at 500 feet per seond will travel 0.17 of an inch. That might not seem much but when you're taking photos from 3 - 4 feet away, it's quite a distance. It leaves a blur of approximately the length of the pellet or rather doubles the length of a blurry pellet.

The following image (if it posts) is of a blurry pellet after it has been slowed by impacting a razor blade. The exposure was 1/38,000th.

I want to try to do this kindof thing with LEDs or at least to try it and at least have some fun attempting it.

<img src = "https://lh4.googleusercontent.com/-1hNyjojhl3A/Tsfwn6O48II/AAAAAAAAB2E/wyXqy7HpmSw/w798-h532-no/photo7.jpg">

 

[Phil Allison]

"John Larkin"

If I could pulse light from those LEDs at 1/50,000th second I would be
happy. If I could get down to 1/100,000 second I would be ecstatic.

Doesn't sound hard. One gotcha is that a white LED is a blue LED with a
blue-to-yellow conversion phosphor. I don't know the response speed of the
phosphor. You might goodle that and make sure it's not a problem.

** Most white LEDs use similar converting phosphors, which have virtually no
persistence.

Luxeon specs a rise time of 100nS and the fall time is similar.

https://www.sparkfun.com/datasheets/Components/Luxeon-III.pdf

" Instant light ( less than 100nS ) "


.... Phil

 

[David Eather]

On Sat, 03 Aug 2013 14:16:59 +1000, John Larkin
&lt;jjlarkin@highnotlandthistechnologypart.com&gt; wrote:

On Fri, 2 Aug 2013 19:43:18 -0700 (PDT), sagephotoworld@gmail.com wrote:

OK.

I want to build a lower-power LED microflash. You're probably familiar
with Edgerton's microflash that produced a 1/1,000,000 second flash by
arcing 50,000v across an air gap that had been ionized by 25,000v and
is commonly used to photograph bullets in flight?

The fastest flash available from xenon tubes is 1/110,000 second and a
flash such as a Canon 580EX2 runs at a maximum of 1/38.000th second.

What I want to do is to build an LED version of a flash since LEDs
though lower in power, will pulse very quickly. I'm not planning to
build the ultimate LED microflash. I have an LED light panel that I
built with about 170 white LEDs in parallel. That runs happily off 2 x
C cells.

If I could pulse light from those LEDs at 1/50,000th second I would be
happy. If I could get down to 1/100,000 second I would be ecstatic.

Doesn't sound hard. One gotcha is that a white LED is a blue LED with a
blue-to-yellow conversion phosphor. I don't know the response speed of
the
phosphor. You might goodle that and make sure it's not a problem.

He can use RGB LEDs - no phosphor at all

I realise it probably wouldn't be very bright and that I might well
have to crank my ISO upto 1600 but I'd like to have a go and play with
it; maybe try it with different LEDs and different voltages later.

I don't want to use any ICs in the circuit because they tend to
introduce both complications and possible frequency problems. For
example, in 1/38,000th of a second, a .177 airgun pellet travelling at
500 feet per seond will travel 0.17 of an inch. That might not seem
much but when you're taking photos from 3 - 4 feet away, it's quite a
distance. It leaves a blur of approximately the length of the pellet or
rather doubles the length of a blurry pellet.

The following image (if it posts) is of a blurry pellet after it has
been slowed by impacting a razor blade. The exposure was 1/38,000th.

I want to try to do this kindof thing with LEDs or at least to try it
and at least have some fun attempting it.

img src =
"https://lh4.googleusercontent.com/-1hNyjojhl3A/Tsfwn6O48II/AAAAAAAAB2E/wyXqy7HpmSw/w798-h532-no/photo7.jpg"

With no ICs, how would you sync the flash to some event?

Even a cheap disposal flash dumps 5 or so joules into its flashtube.

1 joule might be usable with a fast camera, up close. That's a million
watts for
1 microsecond, say a million amps or so into the LED array. About 6000
amps per
LED.

We have a problem here.