On 2015-06-20, 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.used a fixed pitch font to view: 5V or 12V ------------------+-------+ | | C1 | | || | | in ---||---+---->|-+----+ | | || | | | | .-R6-|--. R1 | R2 R4 | | | | | | | | |\| | | | +-------+--|+\ | // | === | | | >-+--R7-->|--. | C2 | | +-----|-/ | | | | | |/| | .-->|--' | R3 R5 | | | | | | | | 0v +--------------+----+----+-------+-------------+ guessed component values. R1 100k -- sets the scaling down at high frequency C1,C2 100nF R2,R3 33K -- sets the length of the output pulse R4,R5 choose to put approx 1V on the negative input R6 1M positive feedback - inhibits gradual fade in brightness. R7 1K sets LED current. diodes 1n914, 1n4148 or similar. op-amp input range must include 0v, and allow several voltas difference on the inputs. (eg LN324) -- umop apisdn
super simple pulse stretcher
Started by ●June 20, 2015
Reply by ●June 21, 20152015-06-21
Reply by ●June 21, 20152015-06-21
On 6/20/2015 7:35 PM, M Philbrook wrote:> In article <5585dece$0$7017$4c5ecfc7@frugalusenet.com>, > bitrex@de.lete.earthlink.net says... >> >> On 6/20/2015 1:54 PM, John Larkin wrote: >>> On Sat, 20 Jun 2015 12:40:55 -0400, bitrex >>> <bitrex@de.lete.earthlink.net> wrote: >>> >>>> On 6/20/2015 11:11 AM, 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. >>>>> >>>>> NPN emitter follower driving R-C to ground, then a comparator. Use an >>>>> opamp as the comparator. >>>>> >>>>> >>>> >>>> I'm probably going to need to be using something like an LM324A. Will >>>> they work OK in that role? >>> >>> Sure. If you have two sections available, use one open drain to >>> discharge the capacitor, and the other section as the threshold >>> sensor. Quiescent high, RC pulsed low. Easy. >>> >>> We sometimes have a "trigger" LED that is basically a stretched input. >>> In some cases, we want to catch very short pulses - a couple ns - but >>> also indicate a static high input. Laser drivers want that sort of >>> indication. We use a fast one-shot (SN74LVC1G123) and OR its input >>> into the output. >>> >>> >> >> I'm not sure I follow what you mean by using one "open drain." If you >> have a moment could you show me in LTSpice? Also I only got 4 hours >> sleep last night and jesus I'm lazy today. > > > > GND From > /-\ V+ supply ___ > V+ supply ( ) Threshold ref -|___|- > \+/ ___ ___ | > |--+|___|+-+++|___|-GND V -> > + | R4 - > | R3 + | > short pulse + | | > |/ | |\| ||-+ > o--------o-| NPN +-+|-\ longer Pulse ||<- > |> | >-+---o-------+--------+||-+ > + +++|+/ | + > | | |/| | | > +-----+-----+ ___ | | > | +--+|___|+--+ | > + .-. R2 | > --- | | | > C1 --- | |R1 | > + '-' | > | | | > | | | > === === + > GND GND GND > (created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de) > > C1 and R2 is the charge constant hold time before it goes below > Threshold. > > R2 is a + feed back to aid in a little snap action for the off cycle, > make sure to select a value that does not hold + input higher than > the reference input while output is on, otherwise it'll latch. > > Jamie >Great, thanks!
Reply by ●June 21, 20152015-06-21
On 6/20/2015 11:09 PM, Jasen Betts wrote:> On 2015-06-20, 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. > > used a fixed pitch font to view: > > 5V or 12V ------------------+-------+ > | | > C1 | | > || | | > in ---||---+---->|-+----+ | | > || | | | | .-R6-|--. > R1 | R2 R4 | | | > | | | | | |\| | > | | +-------+--|+\ | // > | === | | | >-+--R7-->|--. > | C2 | | +-----|-/ | > | | | | |/| | > .-->|--' | R3 R5 | | > | | | | | | > 0v +--------------+----+----+-------+-------------+ > > guessed component values. > > R1 100k -- sets the scaling down at high frequency > C1,C2 100nF > R2,R3 33K -- sets the length of the output pulse > R4,R5 choose to put approx 1V on the negative input > R6 1M positive feedback - inhibits gradual fade in brightness. > R7 1K sets LED current. > diodes 1n914, 1n4148 or similar. > > op-amp input range must include 0v, and allow several voltas > difference on the inputs. (eg LN324) > >Cool!
Reply by ●June 21, 20152015-06-21
On Sun, 21 Jun 2015 13:53:55 -0400, bitrex <bitrex@de.lete.earthlink.net> wrote:>On 6/20/2015 11:09 PM, Jasen Betts wrote: >> On 2015-06-20, 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. >> >> used a fixed pitch font to view: >> >> 5V or 12V ------------------+-------+ >> | | >> C1 | | >> || | | >> in ---||---+---->|-+----+ | | >> || | | | | .-R6-|--. >> R1 | R2 R4 | | | >> | | | | | |\| | >> | | +-------+--|+\ | // >> | === | | | >-+--R7-->|--. >> | C2 | | +-----|-/ | >> | | | | |/| | >> .-->|--' | R3 R5 | | >> | | | | | | >> 0v +--------------+----+----+-------+-------------+ >> >> guessed component values. >> >> R1 100k -- sets the scaling down at high frequency >> C1,C2 100nF >> R2,R3 33K -- sets the length of the output pulse >> R4,R5 choose to put approx 1V on the negative input >> R6 1M positive feedback - inhibits gradual fade in brightness. >> R7 1K sets LED current. >> diodes 1n914, 1n4148 or similar. >> >> op-amp input range must include 0v, and allow several voltas >> difference on the inputs. (eg LN324) >> >> > >Cool!Yep. Seat of the pants engineering at its finest >:-} ...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 ●June 22, 20152015-06-22
On 6/21/2015 4:20 PM, Jim Thompson wrote:> On Sun, 21 Jun 2015 13:53:55 -0400, bitrex > <bitrex@de.lete.earthlink.net> wrote: > >> On 6/20/2015 11:09 PM, Jasen Betts wrote: >>> On 2015-06-20, 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. >>> >>> used a fixed pitch font to view: >>> >>> 5V or 12V ------------------+-------+ >>> | | >>> C1 | | >>> || | | >>> in ---||---+---->|-+----+ | | >>> || | | | | .-R6-|--. >>> R1 | R2 R4 | | | >>> | | | | | |\| | >>> | | +-------+--|+\ | // >>> | === | | | >-+--R7-->|--. >>> | C2 | | +-----|-/ | >>> | | | | |/| | >>> .-->|--' | R3 R5 | | >>> | | | | | | >>> 0v +--------------+----+----+-------+-------------+ >>> >>> guessed component values. >>> >>> R1 100k -- sets the scaling down at high frequency >>> C1,C2 100nF >>> R2,R3 33K -- sets the length of the output pulse >>> R4,R5 choose to put approx 1V on the negative input >>> R6 1M positive feedback - inhibits gradual fade in brightness. >>> R7 1K sets LED current. >>> diodes 1n914, 1n4148 or similar. >>> >>> op-amp input range must include 0v, and allow several voltas >>> difference on the inputs. (eg LN324) >>> >>> >> >> Cool! > > Yep. Seat of the pants engineering at its finest >:-} > > ...Jim Thompson >In this case is that comment meant as a compliment or pejorative? Or some of both?
Reply by ●June 22, 20152015-06-22
On Mon, 22 Jun 2015 07:51:53 -0400, bitrex <bitrex@de.lete.earthlink.net> wrote:>On 6/21/2015 4:20 PM, Jim Thompson wrote: >> On Sun, 21 Jun 2015 13:53:55 -0400, bitrex >> <bitrex@de.lete.earthlink.net> wrote: >> >>> On 6/20/2015 11:09 PM, Jasen Betts wrote: >>>> On 2015-06-20, 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. >>>> >>>> used a fixed pitch font to view: >>>> >>>> 5V or 12V ------------------+-------+ >>>> | | >>>> C1 | | >>>> || | | >>>> in ---||---+---->|-+----+ | | >>>> || | | | | .-R6-|--. >>>> R1 | R2 R4 | | | >>>> | | | | | |\| | >>>> | | +-------+--|+\ | // >>>> | === | | | >-+--R7-->|--. >>>> | C2 | | +-----|-/ | >>>> | | | | |/| | >>>> .-->|--' | R3 R5 | | >>>> | | | | | | >>>> 0v +--------------+----+----+-------+-------------+ >>>> >>>> guessed component values. >>>> >>>> R1 100k -- sets the scaling down at high frequency >>>> C1,C2 100nF >>>> R2,R3 33K -- sets the length of the output pulse >>>> R4,R5 choose to put approx 1V on the negative input >>>> R6 1M positive feedback - inhibits gradual fade in brightness. >>>> R7 1K sets LED current. >>>> diodes 1n914, 1n4148 or similar. >>>> >>>> op-amp input range must include 0v, and allow several voltas >>>> difference on the inputs. (eg LN324) >>>> >>>> >>> >>> Cool! >> >> Yep. Seat of the pants engineering at its finest >:-} >> >> ...Jim Thompson >> > >In this case is that comment meant as a compliment or pejorative? Or >some of both?Both. Some of concept was on the right track, implementation doesn't work _at_all_! Can you define "stretch duration" requirements? How fast might the input pulses be coming in? Any reason you can't use a 555 timer ?:-) ...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 ●June 22, 20152015-06-22
On 6/22/2015 10:01 AM, Jim Thompson wrote:> On Mon, 22 Jun 2015 07:51:53 -0400, bitrex > <bitrex@de.lete.earthlink.net> wrote: > >> On 6/21/2015 4:20 PM, Jim Thompson wrote: >>> On Sun, 21 Jun 2015 13:53:55 -0400, bitrex >>> <bitrex@de.lete.earthlink.net> wrote: >>> >>>> On 6/20/2015 11:09 PM, Jasen Betts wrote: >>>>> On 2015-06-20, 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. >>>>> >>>>> used a fixed pitch font to view: >>>>> >>>>> 5V or 12V ------------------+-------+ >>>>> | | >>>>> C1 | | >>>>> || | | >>>>> in ---||---+---->|-+----+ | | >>>>> || | | | | .-R6-|--. >>>>> R1 | R2 R4 | | | >>>>> | | | | | |\| | >>>>> | | +-------+--|+\ | // >>>>> | === | | | >-+--R7-->|--. >>>>> | C2 | | +-----|-/ | >>>>> | | | | |/| | >>>>> .-->|--' | R3 R5 | | >>>>> | | | | | | >>>>> 0v +--------------+----+----+-------+-------------+ >>>>> >>>>> guessed component values. >>>>> >>>>> R1 100k -- sets the scaling down at high frequency >>>>> C1,C2 100nF >>>>> R2,R3 33K -- sets the length of the output pulse >>>>> R4,R5 choose to put approx 1V on the negative input >>>>> R6 1M positive feedback - inhibits gradual fade in brightness. >>>>> R7 1K sets LED current. >>>>> diodes 1n914, 1n4148 or similar. >>>>> >>>>> op-amp input range must include 0v, and allow several voltas >>>>> difference on the inputs. (eg LN324) >>>>> >>>>> >>>> >>>> Cool! >>> >>> Yep. Seat of the pants engineering at its finest >:-} >>> >>> ...Jim Thompson >>> >> >> In this case is that comment meant as a compliment or pejorative? Or >> some of both? > > Both. Some of concept was on the right track, implementation doesn't > work _at_all_! > > Can you define "stretch duration" requirements? How fast might the > input pulses be coming in? > > Any reason you can't use a 555 timer ?:-) > > ...Jim Thompson >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 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.
Reply by ●June 22, 20152015-06-22
On Mon, 22 Jun 2015 10:14:49 -0400, bitrex <bitrex@de.lete.earthlink.net> wrote:>On 6/22/2015 10:01 AM, Jim Thompson wrote: >> On Mon, 22 Jun 2015 07:51:53 -0400, bitrex >> <bitrex@de.lete.earthlink.net> wrote: >> >>> On 6/21/2015 4:20 PM, Jim Thompson wrote: >>>> On Sun, 21 Jun 2015 13:53:55 -0400, bitrex >>>> <bitrex@de.lete.earthlink.net> wrote: >>>> >>>>> On 6/20/2015 11:09 PM, Jasen Betts wrote: >>>>>> On 2015-06-20, 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. >>>>>> >>>>>> used a fixed pitch font to view: >>>>>> >>>>>> 5V or 12V ------------------+-------+ >>>>>> | | >>>>>> C1 | | >>>>>> || | | >>>>>> in ---||---+---->|-+----+ | | >>>>>> || | | | | .-R6-|--. >>>>>> R1 | R2 R4 | | | >>>>>> | | | | | |\| | >>>>>> | | +-------+--|+\ | // >>>>>> | === | | | >-+--R7-->|--. >>>>>> | C2 | | +-----|-/ | >>>>>> | | | | |/| | >>>>>> .-->|--' | R3 R5 | | >>>>>> | | | | | | >>>>>> 0v +--------------+----+----+-------+-------------+ >>>>>> >>>>>> guessed component values. >>>>>> >>>>>> R1 100k -- sets the scaling down at high frequency >>>>>> C1,C2 100nF >>>>>> R2,R3 33K -- sets the length of the output pulse >>>>>> R4,R5 choose to put approx 1V on the negative input >>>>>> R6 1M positive feedback - inhibits gradual fade in brightness. >>>>>> R7 1K sets LED current. >>>>>> diodes 1n914, 1n4148 or similar. >>>>>> >>>>>> op-amp input range must include 0v, and allow several voltas >>>>>> difference on the inputs. (eg LN324) >>>>>> >>>>>> >>>>> >>>>> Cool! >>>> >>>> Yep. Seat of the pants engineering at its finest >:-} >>>> >>>> ...Jim Thompson >>>> >>> >>> In this case is that comment meant as a compliment or pejorative? Or >>> some of both? >> >> Both. Some of concept was on the right track, implementation doesn't >> work _at_all_! >> >> Can you define "stretch duration" requirements? How fast might the >> input pulses be coming in? >> >> Any reason you can't use a 555 timer ?:-) >> >> ...Jim Thompson >> > >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 > >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. >Can you "see" 50ms on and 50ms off? You say you have free OpAmp "sections" (plural?). How many sections might be used? 2-3 sections would make it a fairly easy task to get all your desired features. ...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 ●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 ●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 lengthWhy 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.-- Regards, Martin Brown
