> On Sat, 20 Jun 2015 09:08:31 -0400, bitrex
> <bitrex@de.lete.earthlink.net> wrote:
>
>> I have a need to take a square pulse of 0V/+5V and about 5-10ms
>> duration, and stretch it out long enough to flash a LED brightly enough
>> to be visible indoors under "ordinary" lighting conditions.
>>
>> I currently only have op-amps on the board and would rather not add any
>> logic ICs to do this. So using low-speed op amps and discretes would be
>> fine. The pulse source into the stretcher would be low impedance.
>>
>> An optional feature would be to have the "stretch" duration decrease the
>> more rapidly pulses are coming into the circuit. But that is not a
>> requirement if it needs significant complexity.
>
> See BitrexStretcher.pdf on the S.E.D/Schematics Page of my website.
>
> ...Jim Thompson
>
Oops, for some reason I just noticed this now. Thanks!
Reply by whit3rd●June 23, 20152015-06-23
On Monday, June 22, 2015 at 11:48:39 AM UTC-7, Jim Thompson wrote:
> An ordinary pulse stretcher will produce flashes of width "T" until
> the incoming pulse spacing is less than "T", then steady.
>
> Seems to me like the trivial solution would be a toggle-flop, driving
> the LED with Q.
I've done two RC-driven LEDs, from both Q and /Q of a toggle flop,
just so one would register close-spaced pulses. All we had in
the drawer were 74HC74, but it's a lot easier wiring to
a '74HC73 JK to do this task. Less fiddling with which inputs
to strap high, and which low... they're all high.
For a while, in the 1980s, 'logic probe' high/low/pulse detector
circuits were a rage. There was lots of cleverness expended on
getting blinkie lights to divulge useful circuit info. That's about
the time everyone started noticing the '555
Reply by ●June 22, 20152015-06-22
On Monday, June 22, 2015 at 4:27:08 PM UTC-4, John Larkin wrote:
> On Sat, 20 Jun 2015 09:08:31 -0400, bitrex
> <bitrex@de.lete.earthlink.net> wrote:
>
> >I have a need to take a square pulse of 0V/+5V and about 5-10ms
> >duration, and stretch it out long enough to flash a LED brightly enough
> >to be visible indoors under "ordinary" lighting conditions.
> >
> >I currently only have op-amps on the board and would rather not add any
> >logic ICs to do this. So using low-speed op amps and discretes would be
> >fine. The pulse source into the stretcher would be low impedance.
> >
> >An optional feature would be to have the "stretch" duration decrease the
> >more rapidly pulses are coming into the circuit. But that is not a
> >requirement if it needs significant complexity.
>
> This is pretty simple:
>
> https://dl.dropboxusercontent.com/u/53724080/Circuits/Timing/Stretcher_Min.JPG
>
> Optional R2 limits the peak cap current, and sets charging time. R1
> sets LED current and decay time. Stretch ratios like 50:1 might be
> feasible. The power supplies need to be able to deliver the peak
> charging current.
>
> LED brightness will sort of follow the input pattern.
>
>
> --
>
> John Larkin Highland Technology, Inc
> picosecond timing precision measurement
>
> jlarkin att highlandtechnology dott com
> http://www.highlandtechnology.com
The OA prototype monostable, let the OP figure out how to adapt it:
Please view in a fixed-width font such as Courier.
.
.
.
.
.
. --
. | Cc |\ ---------
. | >-----||---+----------|-\ |
. -- | | > ---+--> |
. [R1] ---|+/ | ---
. | | |/ |
. | | |
. --- +----||-----
. com | C
. [R2] T
. |
. |
. |
. ---
. V-
.
.
.
Reply by John Larkin●June 22, 20152015-06-22
On Sat, 20 Jun 2015 09:08:31 -0400, bitrex
<bitrex@de.lete.earthlink.net> wrote:
>I have a need to take a square pulse of 0V/+5V and about 5-10ms
>duration, and stretch it out long enough to flash a LED brightly enough
>to be visible indoors under "ordinary" lighting conditions.
>
>I currently only have op-amps on the board and would rather not add any
>logic ICs to do this. So using low-speed op amps and discretes would be
>fine. The pulse source into the stretcher would be low impedance.
>
>An optional feature would be to have the "stretch" duration decrease the
>more rapidly pulses are coming into the circuit. But that is not a
>requirement if it needs significant complexity.
This is pretty simple:
https://dl.dropboxusercontent.com/u/53724080/Circuits/Timing/Stretcher_Min.JPG
Optional R2 limits the peak cap current, and sets charging time. R1
sets LED current and decay time. Stretch ratios like 50:1 might be
feasible. The power supplies need to be able to deliver the peak
charging current.
LED brightness will sort of follow the input pattern.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Reply by Jim Thompson●June 22, 20152015-06-22
On Mon, 22 Jun 2015 12:58:19 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>On Sat, 20 Jun 2015 09:08:31 -0400, bitrex
><bitrex@de.lete.earthlink.net> wrote:
>
>>I have a need to take a square pulse of 0V/+5V and about 5-10ms
>>duration, and stretch it out long enough to flash a LED brightly enough
>>to be visible indoors under "ordinary" lighting conditions.
>>
>>I currently only have op-amps on the board and would rather not add any
>>logic ICs to do this. So using low-speed op amps and discretes would be
>>fine. The pulse source into the stretcher would be low impedance.
>>
>>An optional feature would be to have the "stretch" duration decrease the
>>more rapidly pulses are coming into the circuit. But that is not a
>>requirement if it needs significant complexity.
>
>See BitrexStretcher.pdf on the S.E.D/Schematics Page of my website.
>
> ...Jim Thompson
If you insist on using discrete's, see ToggleFlopAncient.pdf on the
same page >:-}
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)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.
Reply by Jim Thompson●June 22, 20152015-06-22
On Sat, 20 Jun 2015 09:08:31 -0400, bitrex
<bitrex@de.lete.earthlink.net> wrote:
>I have a need to take a square pulse of 0V/+5V and about 5-10ms
>duration, and stretch it out long enough to flash a LED brightly enough
>to be visible indoors under "ordinary" lighting conditions.
>
>I currently only have op-amps on the board and would rather not add any
>logic ICs to do this. So using low-speed op amps and discretes would be
>fine. The pulse source into the stretcher would be low impedance.
>
>An optional feature would be to have the "stretch" duration decrease the
>more rapidly pulses are coming into the circuit. But that is not a
>requirement if it needs significant complexity.
See BitrexStretcher.pdf on the S.E.D/Schematics Page of my website.
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)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.
Reply by Jim Thompson●June 22, 20152015-06-22
On Mon, 22 Jun 2015 13:05:49 -0400, bitrex
<bitrex@de.lete.earthlink.net> wrote:
>On 6/22/2015 10:38 AM, Jim Thompson wrote:
>> On Mon, 22 Jun 2015 10:14:49 -0400, bitrex
>> <bitrex@de.lete.earthlink.net> wrote:
>>
>> [snip]
>>>
>>> I don't know, I guess a realistic upper bound for how fast the input
>>> pulses are coming in would be like, 32nd notes at 200-something beats
>>> per minute? Whatever that works out to...100 ms I guess? That might be
>>> a good stretch length
>>>
>>
>> 200*32/60 = 106.67 beats/sec (if I understand what you are saying)...
>> so 10ms :-(... don't think you can discern that.
>>
>> ...Jim Thompson
>>
>
>Ah, yeah I slipped a decimal point there. At 10 ms that will be steady
>on for sure, but that's OK.
An ordinary pulse stretcher will produce flashes of width "T" until
the incoming pulse spacing is less than "T", then steady.
Seems to me like the trivial solution would be a toggle-flop, driving
the LED with Q.
Jazzier, combine toggle flop with stretcher so that pulse width is
restricted to TAU, until Q "snuffs" off the width at high pulse rates.
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)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.
Reply by bitrex●June 22, 20152015-06-22
On 6/22/2015 10:38 AM, Jim Thompson wrote:
> On Mon, 22 Jun 2015 10:14:49 -0400, bitrex
> <bitrex@de.lete.earthlink.net> wrote:
>
> [snip]
>>
>> I don't know, I guess a realistic upper bound for how fast the input
>> pulses are coming in would be like, 32nd notes at 200-something beats
>> per minute? Whatever that works out to...100 ms I guess? That might be
>> a good stretch length
>>
>
> 200*32/60 = 106.67 beats/sec (if I understand what you are saying)...
> so 10ms :-(... don't think you can discern that.
>
> ...Jim Thompson
>
Ah, yeah I slipped a decimal point there. At 10 ms that will be steady
on for sure, but that's OK.
Reply by Jim Thompson●June 22, 20152015-06-22
On Mon, 22 Jun 2015 10:14:49 -0400, bitrex
<bitrex@de.lete.earthlink.net> wrote:
[snip]
>
>I don't know, I guess a realistic upper bound for how fast the input
>pulses are coming in would be like, 32nd notes at 200-something beats
>per minute? Whatever that works out to...100 ms I guess? That might be
>a good stretch length
>
200*32/60 = 106.67 beats/sec (if I understand what you are saying)...
so 10ms :-(... don't think you can discern that.
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)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.
Reply by Martin Brown●June 22, 20152015-06-22
On 22/06/2015 15:14, bitrex wrote:
> They're sync pulses from one of those old musical instrument sequencers
> of the type from like, the late 1970s, before MIDI was invented. The
> only way to interface gear was with a gate pulse and a control voltage.
>
> I don't know, I guess a realistic upper bound for how fast the input
> pulses are coming in would be like, 32nd notes at 200-something beats
> per minute? Whatever that works out to...100 ms I guess? That might be
> a good stretch length
Why does it need pulse stretching? - wouldn't it be sufficient to drive
enough current through the LED in 5mS to make it bright enough to see?
Some phone camera flashguns are LED based these days.
> The 555 timer is really cheap in quantity but the bipolar version draws
> a lot of quiescent current and I'm running on batteries. The CMOS is
> more expensive. And I'll probably have free opamp sections.