Programmable IR LED Flasher Circuit -- How to Build?

[[email protected]]

I'm trying to build an LED flasher (as small as possible -- operating
on a 9V battery) like this...

http://www.ownthenight.com/html/Products/Illuminators/illphoenix.html

Here's how it works...

You attach it to the battery then program the flash sequence by
shorting the terminals on top. Once you first short the terminals, the
time starts counting and you have a specified amount of time (about 5-6
seconds) to program a sequence. As you short the terminals, you see a
visible green LED that indicates on. You tap out your sequence and
when the time is up, it stops accepting programming.

If you view it through night-vision scopes, you can see the pattern you
input flashing in IR.

From the look of the commercial device, there are only 2 ICs, both of

which I'm assuming are simple off-the-shelf logic (could be a bad
assumption). I had originally thought 555 timer and shift register.

My idea for the design was that a timer clocks in your input to a shift
register. The longer you short the terminals, the more 1s are clocked
in. This results in a pattern of varying pulse widths that can then
keep cycling through the shift register and illuminate the LEDs.

I was unable to find similar circuits on the web, so I'm not sure
that's the right approach. I had although thought of individual
one-shots somehow keeping the outputs high/low with something clocking
them to change it based on what you input.

I can't figure out the "memory" of it, but I'd assume it's not
something complex -- that's why I keep thinking "shift register". For
it to work though, it would have to be many bits wide. I found some
8-pin ICs that have 16-bit serial registers in them, so if the duration
of the one-shots output is 1/3 second, then the shift register would
support a 5-second programming duration.

Any ideas?

Thanks.

 

[Homer J Simpson]

You attach it to the battery then program the flash sequence by
shorting the terminals on top. Once you first short the terminals, the
time starts counting and you have a specified amount of time (about 5-6
seconds) to program a sequence. As you short the terminals, you see a
visible green LED that indicates on. You tap out your sequence and
when the time is up, it stops accepting programming.

Microchip.com

 

[[email protected]]

So it's a PIC microcontroller? Which one? What's the rest of the
circuit?

 

[Homer J Simpson]

So it's a PIC microcontroller? Which one? What's the rest of the
circuit?

That's why they pay us the big bucks!

 

[[email protected]]

What?

 

[John Fields]

What?

---
Yup, that's why they pay us the big bucks.

You might get someone to work up a design for you, complete with
schematic, bill of materials, and working source code, all for free,
but I doubt it, since that what we get paid the big bucks to do.

If you need some of the devices, why don't you just buy them?

BTW, please bottom-post.

 

[[email protected]]

I'm trying to build an LED flasher (as small as possible -- operating
on a 9V battery) like this...

http://www.ownthenight.com/html/Products/Illuminators/illphoenix.html

Here's how it works...

You attach it to the battery then program the flash sequence by
shorting the terminals on top. Once you first short the terminals, the
time starts counting and you have a specified amount of time (about 5-6
seconds) to program a sequence. As you short the terminals, you see a
visible green LED that indicates on. You tap out your sequence and
when the time is up, it stops accepting programming.

If you view it through night-vision scopes, you can see the pattern you
input flashing in IR.

which I'm assuming are simple off-the-shelf logic (could be a bad
assumption). I had originally thought 555 timer and shift register.

My idea for the design was that a timer clocks in your input to a shift
register. The longer you short the terminals, the more 1s are clocked
in. This results in a pattern of varying pulse widths that can then
keep cycling through the shift register and illuminate the LEDs.

I was unable to find similar circuits on the web, so I'm not sure
that's the right approach. I had although thought of individual
one-shots somehow keeping the outputs high/low with something clocking
them to change it based on what you input.

I can't figure out the "memory" of it, but I'd assume it's not
something complex -- that's why I keep thinking "shift register". For
it to work though, it would have to be many bits wide. I found some
8-pin ICs that have 16-bit serial registers in them, so if the duration
of the one-shots output is 1/3 second, then the shift register would
support a 5-second programming duration.

Any ideas?

Thanks.

First of all, death to the 9V battery. Design with AA cells.

Second, by sequence, you do mean the lights flash sequentially? Or is
there a cadence to the flashing? I doubt you could see an individual
LED from any distance, so a pattern of flashing would be dumb. Cadence
is another story. That you could detect over distance.

While a shift register would work, all you are really building is a
state machine. This can be done with D flip flops and an EPROM. Some of
the address lines would be used in making the state machine, and others
would be used in selecting the cadence pattern. One bit in the memory
needs to be reserved for LED on or off. Just write out the K-amp by
hand, then program the memory (assuming you can find a burner).

I'd suggest designing a current source to feed the leds. This will keep
the light output uniform as the battery is drained. You could use two
AA cells and a boost converter instead of the 9V battery. Your choice,
but two AA cells are the same size as a 9V battery, but have much more
juice.

I built a cheesy IR flasher by taking a made in China red led flasher
and replacing the visible leds with IR leds. The Chinese design was so
bad that they paralleled the LEDs. I guess they don't know about
current hogging in China.

Hint: This isn't a big bucks design. High school kids in the valley can
do this.

 

[[email protected]]

I have a better idea. Take your big bucks and shove them up your
arrogant ass. BTW Johnny, please don't be a fucking smart ass. Have a
nice day.

 

[martin griffith]

On 10 Sep 2006 10:23:24 -0700, in sci.electronics.design

So it's a PIC microcontroller? Which one? What's the rest of the
circuit?

There is no "rest of the circuit", it is all written basically as a
text file ( source code), and translated so the pic (bletch) can
understand it

You can download the stuff from microchip, and read through it, and
learn to do it yourself, it take time and patience they you will be
able to say, maybe

"That's why they pay us the big bucks!"

Thats why source code is not available on isohunt


martin

 

[[email protected]]

First of all, death to the 9V battery. Design with AA cells.

Doesn't really matter. I was just going off of the design of the one
I've used.

Second, by sequence, you do mean the lights flash sequentially? Or is
there a cadence to the flashing?

It's a programmable blinking pattern. I guess sequence was the wrong
word. Whatever you tap out on the leads is repeated (about a 5-second
period that repeats). You can actually see it from quite a ways off.
The one that I've used (Phoenix Beacon) has 3 LEDs in it. When you're
looking through night vision devices, you can see it.

I doubt you could see an individual
LED from any distance, so a pattern of flashing would be dumb. Cadence
is another story. That you could detect over distance.

It's for assembling on a drop zone at night. When you have multiple
units in the area and it's dark, a pattern of flashing is very useful.
OK, cadence too. For example, it's long-long-short for one unit.
Short-short-short for another. So by pattern, I mean long and short
bursts.

While a shift register would work, all you are really building is a
state machine. This can be done with D flip flops and an EPROM.

Isn't a shift register just flip flops strung together? Or would it be
better to use them individually? I was just assuming shift register.
It's been years since I've done anything like this.

Some of

the address lines would be used in making the state machine, and others
would be used in selecting the cadence pattern. One bit in the memory
needs to be reserved for LED on or off. Just write out the K-amp by
hand, then program the memory (assuming you can find a burner).

The device has to be "field programmable". You short the two leads and
it starts a 5-second time period. Whatever you tap goes into "memory"
and then that pattern repeats indefinitely (or until the battery dies).

I'd suggest designing a current source to feed the leds. This will keep
the light output uniform as the battery is drained. You could use two
AA cells and a boost converter instead of the 9V battery. Your choice,
but two AA cells are the same size as a 9V battery, but have much more
juice.

AAs would be ok. What's a boost converter?

I built a cheesy IR flasher by taking a made in China red led flasher
and replacing the visible leds with IR leds. The Chinese design was so
bad that they paralleled the LEDs. I guess they don't know about
current hogging in China.



Hint: This isn't a big bucks design. High school kids in the valley can
do this.

I figured as much. That's why I don't want to spend $70-80 on
something like this if I can build it. Plus, I just want to see how it
works.

Thanks for the helpful reply.

 

[[email protected]]

There is no "rest of the circuit", it is all written basically as a
text file ( source code), and translated so the pic (bletch) can
understand it

But how would you program it? The device I have used (Phoenix Beacon)
has two leads on it. You tap out your sequence by shorting the leads.
You have about 5 seconds from the first time you touch them. Whatever
you tap out then repeats indefinitely.

I've never worked with PICs before. Does it have an "input" (something
you can apply voltage to/ground that would put pulses into the PICs
memory and then output the pattern to an LED)?

 

[martin griffith]

On 10 Sep 2006 13:55:15 -0700, in sci.electronics.design

But how would you program it? The device I have used (Phoenix Beacon)
has two leads on it. You tap out your sequence by shorting the leads.
You have about 5 seconds from the first time you touch them. Whatever
you tap out then repeats indefinitely.

I've never worked with PICs before. Does it have an "input" (something
you can apply voltage to/ground that would put pulses into the PICs
memory and then output the pattern to an LED)?

I'm not familiar with pics, its just a microprocessor,

1) you have to create/write a program for the appropiate micro, see
the microchip site.
You define when you write the program what the pins on the micro do,
input or output, maybe both.
2) you then burn the program into the micro
3) then you have fun



martin

 

[[email protected]]

I'm not familiar with pics, its just a microprocessor,

I thought it was called a PIC, but I went back and looked and see that
PIC is the trademarked name for the microcontroller.

I guess I have some reading to do. I never really thought to do
something like this. I had assumed that the beacon was simply built
with "simple" logic parts (gates, counters, shift registers).

Thanks for the replies.

 

[martin griffith]

On 10 Sep 2006 14:12:48 -0700, in sci.electronics.design

I thought it was called a PIC, but I went back and looked and see that
PIC is the trademarked name for the microcontroller.

I guess I have some reading to do. I never really thought to do
something like this. I had assumed that the beacon was simply built
with "simple" logic parts (gates, counters, shift registers).

Thanks for the replies.

Its changed, these days it is easier to program a pic than work out a
555 circuit,because you immense flexibility. For a little project like
this, (when you get a cheap 99$ development kit) the most simple
program will take 5 minutes, but it can be a steep learning curve.

google piclist


martin

 

[Donald]

I'm trying to build an LED flasher (as small as possible -- operating
on a 9V battery) like this...

http://www.ownthenight.com/html/Products/Illuminators/illphoenix.html

For $25, you would be hard pressed to make your own for less.
For $85, you would still need a good reason to build just a few.

Like many here, I have parts on hand to build such a device.
But, do I have the time it would take, or do I want to spend the time
making such a thing. ( even if I did know what it would be used for )

If this is an learning project in building such devices, you have
everything you would need in the following posts.

So what are your goal ?

Are you looking to build a bunch of these, or just one or two ?

Good Luck

donald

 

[John Fields]

I have a better idea. Take your big bucks and shove them up your
arrogant ass. BTW Johnny, please don't be a fucking smart ass. Have a
nice day.

---
Well, now that you've had a little taste of reality and you realize
that you don't know squat, I guess you'll unruffle your feathers,
hit the books, and start the process we've all had to go through in
order to be able to help newbies like you on their way. Good luck,
and have a nice day yourself, dumbass.

 

[[email protected]]

A taste of reality? Ha! I live in a much more real world than you
johnny boy. I don't have to be an arrogant prick just to boost my self
esteem. Come with that type of attitude to my side of the fence and
see if you don't just get bitch slapped into the middle of next week.
(And before you go crying and say that I threatened you, I didn't. I
somehow picture you as that type of guy -- sit behind your computer
terminal and brag about yourself, but wither like a pansy when the real
world smacks you down).

Anyway Johnny, run along and play with your toys. I've grown tired of
this juvenile little game and probably shouldn't have entertained you
this long. You probably have some sort of weird fetish and get off
when people exchange things like this. I want no part of your perverse
little world.

 

[[email protected]]

So what are your goal ?

Mainly just learning. I was looking for some ideas on how to implement
it relatively easy. Yeah, I could spend days and weeks studying, but
beyond this project, I'm not sure I'd do much more.

Are you looking to build a bunch of these, or just one or two ?

One or two. I have a big budget, so I could just buy them, but it
would be a nice to make a few for the learning experience and as a nice
conversation piece.

 

[Don Foreman]

---
Well, now that you've had a little taste of reality and you realize
that you don't know squat, I guess you'll unruffle your feathers,
hit the books, and start the process we've all had to go through in
order to be able to help newbies like you on their way. Good luck,
and have a nice day yourself, dumbass.

He does have a point. If you don't want to be helpful, why not just
ignore him?

 

[Don Foreman]

I have a better idea. Take your big bucks and shove them up your
arrogant ass. BTW Johnny, please don't be a fucking smart ass. Have a
nice day.

Hey, you asked the question! You must expect some of that in an open
newsgroup. Best not to get yer knickers in a knot when it happens,
because it *will* happen. Ignore the chaff, there really are a few
helpful contributors here.

While having a beer with some buds at the lake this weekend, one of
them observed that engineers are a bunch of arrogant assholes. I
broke out laughing -- because I couldn't disagree with him.
Stereotypes like that don't exist without a reason. I worked with
plenty of them when I did it for a living. Some of the good ones were
arrogant, but most of the best ones were not. They didn't need to be.
Engineers work hard, long and constantly to learn their profession and
keep current, and it can be very competitive at times -- so arrogance
sometimes becomes a defense mechanism. I worked with dozens of PhD's
every day. All save two or three were arrogant to some degree. The
two or three that were not are world-class in their fields. An
arrogant or vague response is often a way to avoid saying "I don't
know", or "I don't want you to know how simple it really is". You
do not want an engineer watching your six in most engrng orgs.

Your flasher dingus is very likely based on a simple low-end
microcontroller. There are several ways in which it might work. One
way might be to divide up the 5-second "programming time" into a
number of windows, say 64 or 128 depending on how much memory the
microcontroller has. It then checks periodically to see if the user
is telling it to turn the LED "on" or "off" during the next short
time period. It stores this information in its RAM (random access
memory). In use, it just plays back the sequence it learned.

These devices are quite easy to use once one has learned how to use
them. It is not difficult to learn in the sense of requiring a lot
of technical background, but it isn't trivial either. A high school
kid can do it if he or she is motivated enough to do so. Having a
mentor or taking a course or seminar can help a great deal. Most
young engineers today are quite adept at writing software for these
gadgets, even though their grasp of basic engineering principles often
seems to be quite sketchy.