Yes, I have successfully flashed an LED by 1/2 556. The "on" times and "off"
times are independently adjustable, and all of the values are pretty much
as per usual. With a 4.7 tantalum, I can get the flash rate down to about
1.7 Hz (according to the counter that came with the scope), and, much to
my amazement, with no capacitor AT ALL, it gave a pretty reasonable
approximation of a square wave (admittedly, with a little glitch on the
rising edge) at like over 200 KHz! If I had the motivation, I'd bother
to calculate the capacitance of my ProtoBord, but arithmetic isn't my
favorite thing to do. One thing that I was glad to see happen is that
with the 100K pot in series with the 1K fixed, I actually get a 200:1
range, both for "on" time" and for "off" time, so I guess that means
I can tune the duty cycle from 1% to 99%, and in between them, I can
dick around with the frequency. :-)

Cheers!
Rich

Posting from my other news client, and forgot to switch nyms.

Thanks!
Rich

On Sat, 09 Jun 2007 01:40:10 +0000, The Newsgroup Wacko wrote:

Yes, I have successfully flashed an LED by 1/2 556. The "on" times and
"off" times are independently adjustable, and all of the values are pretty
much as per usual. With a 4.7 tantalum, I can get the flash rate down to
about 1.7 Hz (according to the counter that came with the scope), and,
much to my amazement, with no capacitor AT ALL, it gave a pretty
reasonable approximation of a square wave (admittedly, with a little
glitch on the rising edge) at like over 200 KHz! If I had the motivation,
I'd bother to calculate the capacitance of my ProtoBord, but arithmetic
isn't my favorite thing to do. One thing that I was glad to see happen is
that with the 100K pot in series with the 1K fixed, I actually get a 200:1
range, both for "on" time" and for "off" time, so I guess that means I can
tune the duty cycle from 1% to 99%, and in between them, I can dick around
with the frequency. :-)

Cheers!
Rich

On Sat, 09 Jun 2007 01:42:31 GMT, Rich Grise wrote:

Posting from my other news client, and forgot to switch nyms.

Thanks!
Rich

On Sat, 09 Jun 2007 01:40:10 +0000, The Newsgroup Wacko wrote:

Yes, I have successfully flashed an LED by 1/2 556. The "on" times and
"off" times are independently adjustable, and all of the values are pretty
much as per usual. With a 4.7 tantalum, I can get the flash rate down to
about 1.7 Hz (according to the counter that came with the scope), and,
much to my amazement, with no capacitor AT ALL, it gave a pretty
reasonable approximation of a square wave (admittedly, with a little
glitch on the rising edge) at like over 200 KHz! If I had the motivation,
I'd bother to calculate the capacitance of my ProtoBord, but arithmetic
isn't my favorite thing to do. One thing that I was glad to see happen is
that with the 100K pot in series with the 1K fixed, I actually get a 200:1
range, both for "on" time" and for "off" time, so I guess that means I can
tune the duty cycle from 1% to 99%, and in between them, I can dick around
with the frequency. :-)

Cheers!
Rich


Jeez, what a dope. Not for the post account error... for the post
itself.

How many YEARS did it take you to be able to construct a variable
modulation pulser?

The Newsgroup Wacko wrote:

Yes, I have successfully flashed an LED by 1/2 556.

Use a PIC !

Graham

Yes, use a pic

The picaxe 08M does it in an 8 pin pkg with only Led limiting
resistors for passive parts. Set the delay on or off to the
millisecond. Will flash up to four leds, in any order. On board A/D
if you need it pot adjustable.

Only development board is a serial cable and 9 pin connector. Easy to
learn and use. Works fine on 2 AA batteries, up to 5V, uses very
little power.

I'm coupling them to el cheapo CCD cameras for time lapse photography.
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On Sat, 09 Jun 2007 09:30:57 -0400, default wrote:

Yes, use a pic

The picaxe 08M does it in an 8 pin pkg with only Led limiting
resistors for passive parts. Set the delay on or off to the
millisecond. Will flash up to four leds, in any order. On board A/D
if you need it pot adjustable.

Only development board is a serial cable and 9 pin connector. Easy to
learn and use. Works fine on 2 AA batteries, up to 5V, uses very
little power.

I'm coupling them to el cheapo CCD cameras for time lapse photography.

Wow, something even simpler (in terms of parts count, anyway) than the
now-discontinued LM 3909.

"The Newsgroup Wacko" wrote in message
news:_xnai.3639$3Q4.1591@trnddc05...
Yes, I have successfully flashed an LED by 1/2 556. The "on" times and
"off"
times are independently adjustable, and all of the values are pretty much
as per usual. With a 4.7 tantalum, I can get the flash rate down to about
1.7 Hz (according to the counter that came with the scope), and, much to
my amazement, with no capacitor AT ALL, it gave a pretty reasonable
approximation of a square wave (admittedly, with a little glitch on the
rising edge) at like over 200 KHz! If I had the motivation, I'd bother
to calculate the capacitance of my ProtoBord, but arithmetic isn't my
favorite thing to do. One thing that I was glad to see happen is that
with the 100K pot in series with the 1K fixed, I actually get a 200:1
range, both for "on" time" and for "off" time, so I guess that means
I can tune the duty cycle from 1% to 99%, and in between them, I can
dick around with the frequency. :-)

Cheers!
Rich

I remember those 'flashing' bulbs with the bi metalic strip in them

Colin =^.^=