On Mar 7, 3:12=A0pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote:> On 3/7/2013 12:21 PM, George Herold wrote: > > > Hi guys, =A0I need a little digital pulse stretcher. =A0I've got pulses > > that are 5ns to 25ns in width, and I'd like to bump them all up to all > > be at least 10ns. =A0 I've got a few spare 74HC14 inverters. =A0I was > > thinking of just feeding one through a diode followed by an R/C to > > ground. =A0Any other ways? =A0There might be an extra AND gate too. > > (not my circuit so I'm not quite sure.) > > > Thanks > > > George H. > > (and who ordered the second t in stretcher) > > Something like this: > > http://www.abvolt.com/misc/pulse_stretch.jpg > > You got the idea. > > /* > Placeholder for banal comments > */ > > Vladimir Vassilevsky > DSP and Mixed Signal Designswww.abvolt.comYeah I was thinking of something like that too. The diode thing was an easy 'hack' and seems to be working just fine. (I stuck in 10k and 10pF and have about a 50ns minimum pulse.) Life is good. George H.
Simple pulse stretcher
Started by ●March 7, 2013
Reply by ●March 7, 20132013-03-07
Reply by ●March 7, 20132013-03-07
On Thu, 07 Mar 2013 14:12:45 -0600, Vladimir Vassilevsky <nospam@nowhere.com> wrote:>On 3/7/2013 12:21 PM, George Herold wrote: >> Hi guys, I need a little digital pulse stretcher. I've got pulses >> that are 5ns to 25ns in width, and I'd like to bump them all up to all >> be at least 10ns. I've got a few spare 74HC14 inverters. I was >> thinking of just feeding one through a diode followed by an R/C to >> ground. Any other ways? There might be an extra AND gate too. >> (not my circuit so I'm not quite sure.) >> >> Thanks >> >> George H. >> (and who ordered the second t in stretcher) >> > >Something like this: > >http://www.abvolt.com/misc/pulse_stretch.jpg > >You got the idea. >>/* >Placeholder for banal commentsI think that can double-glitch the output if you tease the input width just right.>*/ >-- 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
Reply by ●March 7, 20132013-03-07
On Thu, 7 Mar 2013 10:21:33 -0800 (PST), George Herold <gherold@teachspin.com> wrote:>Hi guys, I need a little digital pulse stretcher. I've got pulses >that are 5ns to 25ns in width, and I'd like to bump them all up to all >be at least 10ns. I've got a few spare 74HC14 inverters. I was >thinking of just feeding one through a diode followed by an R/C to >ground. Any other ways? There might be an extra AND gate too. >(not my circuit so I'm not quite sure.) > >Thanks > >George H. >(and who ordered the second t in stretcher)--- "Pulse stretcher" implies that the leading edge of the source pulse should be presented at the input of the load simultaneously with its generation, and that its fall should occur after the desired delay. The former is, of course, unrealizable, while the latter is easy. How much delay can you tolerate between the generation of the leading edge of the source pulse and its presentation to the load? -- JF
Reply by ●March 7, 20132013-03-07
On Thu, 7 Mar 2013 11:01:25 -0800 (PST), George Herold <gherold@teachspin.com> wrote:>On Mar 7, 1:33�pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My- >Web-Site.com> wrote: >> On Thu, 7 Mar 2013 10:21:33 -0800 (PST), George Herold >> >> <gher...@teachspin.com> wrote: >> >Hi guys, �I need a little digital pulse stretcher. �I've got pulses >> >that are 5ns to 25ns in width, and I'd like to bump them all up to all >> >be at least 10ns. � I've got a few spare 74HC14 inverters. �I was >> >thinking of just feeding one through a diode followed by an R/C to >> >ground. �Any other ways? �There might be an extra AND gate too. >> >(not my circuit so I'm not quite sure.) >> >> >Thanks >> >> >George H. >> >(and who ordered the second t in stretcher) >> >> Isn't 10ns width just a wee-bit tight for 74HC parts? >> >> � � � � � � � � � � � � � � � � � � � � ...Jim Thompson >> -- >> | James E.Thompson � � � � � � � � � � � � � � � � | � �mens � � | >> | Analog Innovations � � � � � � � � � � � � � � � | � � et � � �| >> | Analog/Mixed-Signal ASIC's and Discrete Systems �| � �manus � �| >> | Phoenix, Arizona �85048 � �Skype: Contacts Only �| � � � � � � | >> | Voice:(480)460-2350 �Fax: Available upon request | �Brass Rat �| >> | E-mail Icon athttp://www.analog-innovations.com| � �1962 � � | >> >> I love to cook with wine. � � Sometimes I even put it in the food. > >OK, maybe I should stretch to 20 ns. > >George H.The diode+RC thing is perfectly feasible with an HC14, likely at 20 ns out and certainly at 30. A bit of inductance in series with the R would be interesting. Here's a variation on Vlad's circuit: https://dl.dropbox.com/u/53724080/SED/Stretcher.JPG -- 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
Reply by ●March 7, 20132013-03-07
George Herold wrote:> On Mar 7, 3:12 pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote: >> On 3/7/2013 12:21 PM, George Herold wrote: >> >>> Hi guys, I need a little digital pulse stretcher. I've got pulses >>> that are 5ns to 25ns in width, and I'd like to bump them all up to all >>> be at least 10ns. I've got a few spare 74HC14 inverters. I was >>> thinking of just feeding one through a diode followed by an R/C to >>> ground. Any other ways? There might be an extra AND gate too. >>> (not my circuit so I'm not quite sure.) >>> Thanks >>> George H. >>> (and who ordered the second t in stretcher) >> Something like this: >> >> http://www.abvolt.com/misc/pulse_stretch.jpg >> >> You got the idea. >> >> /* >> Placeholder for banal comments >> */ >> >> Vladimir Vassilevsky >> DSP and Mixed Signal Designswww.abvolt.com > > Yeah I was thinking of something like that too. The diode thing was > an easy 'hack' and seems to be working just fine. (I stuck in 10k > and 10pF and have about a 50ns minimum pulse.) Life is good. >Diode plus Schmitt is the better solution. The main reason is that doing it with piped-in gates relies on their prop delays. I have seen that blow up in production when people did it. All it takes is one or more manufacturers improving a semiconductor process, things become faster, suddenly the fix ain't working no more. Or only sometimes. Datasheets typically do not specify a guaranteed lower limit on prop delay. For example, there is no entry for it in the "min" column for the 74HC14 from TI: http://www.ti.com/lit/ds/symlink/sn74hc14.pdf -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 7, 20132013-03-07
On Thu, 7 Mar 2013 12:36:39 -0800 (PST), George Herold <gherold@teachspin.com> wrote:>On Mar 7, 3:12�pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote: >> On 3/7/2013 12:21 PM, George Herold wrote: >> >> > Hi guys, �I need a little digital pulse stretcher. �I've got pulses >> > that are 5ns to 25ns in width, and I'd like to bump them all up to all >> > be at least 10ns. � I've got a few spare 74HC14 inverters. �I was >> > thinking of just feeding one through a diode followed by an R/C to >> > ground. �Any other ways? �There might be an extra AND gate too. >> > (not my circuit so I'm not quite sure.) >> >> > Thanks >> >> > George H. >> > (and who ordered the second t in stretcher) >> >> Something like this: >> >> http://www.abvolt.com/misc/pulse_stretch.jpg >> >> You got the idea. >> >> /* >> Placeholder for banal comments >> */ >> >> Vladimir Vassilevsky >> DSP and Mixed Signal Designswww.abvolt.com > >Yeah I was thinking of something like that too. The diode thing was >an easy 'hack' and seems to be working just fine. (I stuck in 10k >and 10pF and have about a 50ns minimum pulse.) Life is good. > >George H.Just make sure the schottky has low c, a couple of pF or less. -- 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
Reply by ●March 7, 20132013-03-07
On Thu, 07 Mar 2013 12:56:22 -0800, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:>On Thu, 7 Mar 2013 11:01:25 -0800 (PST), George Herold <gherold@teachspin.com> >wrote: > >>On Mar 7, 1:33�pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My- >>Web-Site.com> wrote: >>> On Thu, 7 Mar 2013 10:21:33 -0800 (PST), George Herold >>> >>> <gher...@teachspin.com> wrote: >>> >Hi guys, �I need a little digital pulse stretcher. �I've got pulses >>> >that are 5ns to 25ns in width, and I'd like to bump them all up to all >>> >be at least 10ns. � I've got a few spare 74HC14 inverters. �I was >>> >thinking of just feeding one through a diode followed by an R/C to >>> >ground. �Any other ways? �There might be an extra AND gate too. >>> >(not my circuit so I'm not quite sure.) >>> >>> >Thanks >>> >>> >George H. >>> >(and who ordered the second t in stretcher) >>> >>> Isn't 10ns width just a wee-bit tight for 74HC parts? >>> >>> � � � � � � � � � � � � � � � � � � � � ...Jim Thompson >>> -- >>> | James E.Thompson � � � � � � � � � � � � � � � � | � �mens � � | >>> | Analog Innovations � � � � � � � � � � � � � � � | � � et � � �| >>> | Analog/Mixed-Signal ASIC's and Discrete Systems �| � �manus � �| >>> | Phoenix, Arizona �85048 � �Skype: Contacts Only �| � � � � � � | >>> | Voice:(480)460-2350 �Fax: Available upon request | �Brass Rat �| >>> | E-mail Icon athttp://www.analog-innovations.com| � �1962 � � | >>> >>> I love to cook with wine. � � Sometimes I even put it in the food. >> >>OK, maybe I should stretch to 20 ns. >> >>George H. > >The diode+RC thing is perfectly feasible with an HC14, likely at 20 ns out and >certainly at 30. > >A bit of inductance in series with the R would be interesting. > >Here's a variation on Vlad's circuit: > >https://dl.dropbox.com/u/53724080/SED/Stretcher.JPG--- You've still got the initial gate delay from input to output, and the prop delay through the buffers isn't exactly precise... -- JF
Reply by ●March 7, 20132013-03-07
On Thu, 07 Mar 2013 15:08:49 -0600, John Fields <jfields@austininstruments.com> wrote:>On Thu, 07 Mar 2013 12:56:22 -0800, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>On Thu, 7 Mar 2013 11:01:25 -0800 (PST), George Herold <gherold@teachspin.com> >>wrote: >> >>>On Mar 7, 1:33�pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My- >>>Web-Site.com> wrote: >>>> On Thu, 7 Mar 2013 10:21:33 -0800 (PST), George Herold >>>> >>>> <gher...@teachspin.com> wrote: >>>> >Hi guys, �I need a little digital pulse stretcher. �I've got pulses >>>> >that are 5ns to 25ns in width, and I'd like to bump them all up to all >>>> >be at least 10ns. � I've got a few spare 74HC14 inverters. �I was >>>> >thinking of just feeding one through a diode followed by an R/C to >>>> >ground. �Any other ways? �There might be an extra AND gate too. >>>> >(not my circuit so I'm not quite sure.) >>>> >>>> >Thanks >>>> >>>> >George H. >>>> >(and who ordered the second t in stretcher) >>>> >>>> Isn't 10ns width just a wee-bit tight for 74HC parts? >>>> >>>> � � � � � � � � � � � � � � � � � � � � ...Jim Thompson >>>> -- >>>> | James E.Thompson � � � � � � � � � � � � � � � � | � �mens � � | >>>> | Analog Innovations � � � � � � � � � � � � � � � | � � et � � �| >>>> | Analog/Mixed-Signal ASIC's and Discrete Systems �| � �manus � �| >>>> | Phoenix, Arizona �85048 � �Skype: Contacts Only �| � � � � � � | >>>> | Voice:(480)460-2350 �Fax: Available upon request | �Brass Rat �| >>>> | E-mail Icon athttp://www.analog-innovations.com| � �1962 � � | >>>> >>>> I love to cook with wine. � � Sometimes I even put it in the food. >>> >>>OK, maybe I should stretch to 20 ns. >>> >>>George H. >> >>The diode+RC thing is perfectly feasible with an HC14, likely at 20 ns out and >>certainly at 30. >> >>A bit of inductance in series with the R would be interesting. >> >>Here's a variation on Vlad's circuit: >> >>https://dl.dropbox.com/u/53724080/SED/Stretcher.JPG > >--- >You've still got the initial gate delay from input to output,That's pretty much unavoidable. I doubt that it matters to George. and the>prop delay through the buffers isn't exactly precise...How do you know that? I didn't specify the parts, other than max PD. They could be implemented as a tapped delay line, passive or silicon. Or one could trim Vcc to tweak prop delay. There are lots of possibilities. Post something better. -- 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
Reply by ●March 7, 20132013-03-07
On Thu, 07 Mar 2013 13:32:22 -0800, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:>On Thu, 07 Mar 2013 15:08:49 -0600, John Fields <jfields@austininstruments.com> >wrote: > >>On Thu, 07 Mar 2013 12:56:22 -0800, John Larkin >><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Thu, 7 Mar 2013 11:01:25 -0800 (PST), George Herold <gherold@teachspin.com> >>>wrote: >>> >>>>On Mar 7, 1:33�pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My- >>>>Web-Site.com> wrote: >>>>> On Thu, 7 Mar 2013 10:21:33 -0800 (PST), George Herold >>>>> >>>>> <gher...@teachspin.com> wrote: >>>>> >Hi guys, �I need a little digital pulse stretcher. �I've got pulses >>>>> >that are 5ns to 25ns in width, and I'd like to bump them all up to all >>>>> >be at least 10ns. � I've got a few spare 74HC14 inverters. �I was >>>>> >thinking of just feeding one through a diode followed by an R/C to >>>>> >ground. �Any other ways? �There might be an extra AND gate too. >>>>> >(not my circuit so I'm not quite sure.) >>>>> >>>>> >Thanks >>>>> >>>>> >George H. >>>>> >(and who ordered the second t in stretcher) >>>>> >>>>> Isn't 10ns width just a wee-bit tight for 74HC parts? >>>>> >>>>> � � � � � � � � � � � � � � � � � � � � ...Jim Thompson >>>>> -- >>>>> | James E.Thompson � � � � � � � � � � � � � � � � | � �mens � � | >>>>> | Analog Innovations � � � � � � � � � � � � � � � | � � et � � �| >>>>> | Analog/Mixed-Signal ASIC's and Discrete Systems �| � �manus � �| >>>>> | Phoenix, Arizona �85048 � �Skype: Contacts Only �| � � � � � � | >>>>> | Voice:(480)460-2350 �Fax: Available upon request | �Brass Rat �| >>>>> | E-mail Icon athttp://www.analog-innovations.com| � �1962 � � | >>>>> >>>>> I love to cook with wine. � � Sometimes I even put it in the food. >>>> >>>>OK, maybe I should stretch to 20 ns. >>>> >>>>George H. >>> >>>The diode+RC thing is perfectly feasible with an HC14, likely at 20 ns out and >>>certainly at 30. >>> >>>A bit of inductance in series with the R would be interesting. >>> >>>Here's a variation on Vlad's circuit: >>> >>>https://dl.dropbox.com/u/53724080/SED/Stretcher.JPG >> >>--- >>You've still got the initial gate delay from input to output, > >That's pretty much unavoidable. I doubt that it matters to George.--- Maybe not, but I posted a message to him asking for clarification, just to resolve the issue. You, on the other hand, opted to second-guess him and subjugate him to your will. ---> and the prop delay through the buffers isn't exactly precise... > >How do you know that?--- I read the data sheet. --->I didn't specify the parts, other than max PD.--- Not true; you specified the HC14 --->They could be implemented as a tapped delay line, passive or silicon. Or one could trim >Vcc to tweak prop delay. There are lots of possibilities.--- Which you didn't allude to in your initial response, so now they're afterthoughts which you're trying to use to dig yourself out of the grave you dug for yourself. --->Post something better.--- OK, From "Einstein's Theory of Relativity" by Max Born, we have: v� sqrt (1-beta�) = sqrt 1- --- ac� -- JF
Reply by ●March 7, 20132013-03-07
On Thu, 07 Mar 2013 16:36:35 -0600, John Fields <jfields@austininstruments.com> wrote:>On Thu, 07 Mar 2013 13:32:22 -0800, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>On Thu, 07 Mar 2013 15:08:49 -0600, John Fields <jfields@austininstruments.com> >>wrote: >> >>>On Thu, 07 Mar 2013 12:56:22 -0800, John Larkin >>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>On Thu, 7 Mar 2013 11:01:25 -0800 (PST), George Herold <gherold@teachspin.com> >>>>wrote: >>>> >>>>>On Mar 7, 1:33�pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My- >>>>>Web-Site.com> wrote: >>>>>> On Thu, 7 Mar 2013 10:21:33 -0800 (PST), George Herold >>>>>> >>>>>> <gher...@teachspin.com> wrote: >>>>>> >Hi guys, �I need a little digital pulse stretcher. �I've got pulses >>>>>> >that are 5ns to 25ns in width, and I'd like to bump them all up to all >>>>>> >be at least 10ns. � I've got a few spare 74HC14 inverters. �I was >>>>>> >thinking of just feeding one through a diode followed by an R/C to >>>>>> >ground. �Any other ways? �There might be an extra AND gate too. >>>>>> >(not my circuit so I'm not quite sure.) >>>>>> >>>>>> >Thanks >>>>>> >>>>>> >George H. >>>>>> >(and who ordered the second t in stretcher) >>>>>> >>>>>> Isn't 10ns width just a wee-bit tight for 74HC parts? >>>>>> >>>>>> � � � � � � � � � � � � � � � � � � � � ...Jim Thompson >>>>>> -- >>>>>> | James E.Thompson � � � � � � � � � � � � � � � � | � �mens � � | >>>>>> | Analog Innovations � � � � � � � � � � � � � � � | � � et � � �| >>>>>> | Analog/Mixed-Signal ASIC's and Discrete Systems �| � �manus � �| >>>>>> | Phoenix, Arizona �85048 � �Skype: Contacts Only �| � � � � � � | >>>>>> | Voice:(480)460-2350 �Fax: Available upon request | �Brass Rat �| >>>>>> | E-mail Icon athttp://www.analog-innovations.com| � �1962 � � | >>>>>> >>>>>> I love to cook with wine. � � Sometimes I even put it in the food. >>>>> >>>>>OK, maybe I should stretch to 20 ns. >>>>> >>>>>George H. >>>> >>>>The diode+RC thing is perfectly feasible with an HC14, likely at 20 ns out and >>>>certainly at 30. >>>> >>>>A bit of inductance in series with the R would be interesting. >>>> >>>>Here's a variation on Vlad's circuit: >>>> >>>>https://dl.dropbox.com/u/53724080/SED/Stretcher.JPG >>> >>>--- >>>You've still got the initial gate delay from input to output, >> >>That's pretty much unavoidable. I doubt that it matters to George. > >--- >Maybe not, but I posted a message to him asking for clarification, >just to resolve the issue. > >You, on the other hand, opted to second-guess him and subjugate him to >your will. >--- > >> and the prop delay through the buffers isn't exactly precise... >> >>How do you know that? > >--- >I read the data sheet. >--- > >>I didn't specify the parts, other than max PD. > >--- >Not true; you specified the HC14 >--- > >>They could be implemented as a tapped delay line, passive or silicon. Or one could trim >Vcc to tweak prop delay. There are lots of possibilities. > >--- >Which you didn't allude to in your initial response, so now they're >afterthoughts which you're trying to use to dig yourself out of the >grave you dug for yourself. >--- > >>Post something better. > >--- >OK, > >From "Einstein's Theory of Relativity" by Max Born, we have: > v� >sqrt (1-beta�) = sqrt 1- --- > ac�What a sad old dork. -- 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
