On 6 Jun 2016 14:55:16 -0700, Winfield Hill <hill@rowland.harvard.edu> wrote:>klaus.kragelund@gmail.com wrote... >> >> Just a question, you are paralleling the 74LVC2G04 >> inverters. Is that safe to do? > > I'd say yes, indeedie! Note they're both in the > same package, and likely have identical propagation > delays, etc.Sounds like a delta-I problem in the making. I do my best to drive the two subcircuits out of phase (I'm currently using LVC2G04s for clock re-drivers.
cotton-pickin Pulse Picker
Started by ●June 5, 2016
Reply by ●June 6, 20162016-06-06
Reply by ●June 6, 20162016-06-06
On Mon, 6 Jun 2016 12:56:54 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 06/06/2016 12:49 PM, John Larkin wrote: >> On Mon, 6 Jun 2016 12:23:26 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 06/06/2016 12:19 PM, John Larkin wrote: >>>> On 6 Jun 2016 08:34:47 -0700, Winfield Hill <hill@rowland.harvard.edu> >>>> wrote: >>>> >>>>> George Herold wrote... >>>>>> Winfield Hill wrote: >>>>>>> Phil Hobbs wrote... >>>>>>>> >>>>>>>> Something with a nice bulkhead thread that transfers the >>>>>>>> stress to the box instead of the solder joints is very >>>>>>>> reassuring. (You do have to let the board move around a bit.) >>>>>>> >>>>>>> As I mentioned, the ones I'm using have such a feature, >>>>>>> and the wire is soldered. BTW, I added a pic of the pcb, >>>>>>> panel and connectors from the back to the dropbox folder. >>>>>> >>>>>> Oh, what are those BNC "header" type things? >>>>>> Are they custom? >>>>> >>>>> Were you asking me? My parts were Molex 73415-3980, >>>>> http://www.molex.com/molex/products/datasheet.jsp?part=active/0734153980_RF_COAX_CONNECTORS.xml >>>> >>>> Nice, but my picoseconds wouldn't make it around the bends. >>>> >>>> Calling this a "75 ohm" connector is interesting too. >>>> >>>> >>> >>> Probably more about the pin diameter than anything. >>> >>> Cheers >>> >>> Phil Hobbs >> >> BNCs are good to roughly 3 GHz, 100 ps maybe, so those connectors >> might be OK. Maybe a little inductive. >> >> We don't use BNCs on anything faster than about 500 ps. A good BNC is >> actually pretty impressive at high frequencies. > >A lot of my stuff goes on optical tables, where BNC is *de rigueur*, >being both traditional and very practical, even for low frequency stuff. > >For use inside larger systems, I've been designing in a lot of >Displayport connectors lately. You get four lanes of shielded twisted >pair plus control wires, it has a retaining catch so it doesn't jiggle >loose, and it's cheap like borscht. >HDMI are interesting, too. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●June 6, 20162016-06-06
On 6 Jun 2016 14:53:04 -0700, Winfield Hill <hill@rowland.harvard.edu> wrote:>John Larkin wrote... >> >> Winfield Hill wrote: >>> George Herold wrote... >>>> Winfield Hill wrote: >>>>> Phil Hobbs wrote... >>>>>> >>>>>> Something with a nice bulkhead thread that transfers the >>>>>> stress to the box instead of the solder joints is very >>>>>> reassuring. (You do have to let the board move around a bit.) >>>>> >>>>> As I mentioned, the ones I'm using have such a feature, >>>>> and the wire is soldered. BTW, I added a pic of the pcb, >>>>> panel and connectors from the back to the dropbox folder. >>>> >>>> Oh, what are those BNC "header" type things? >>>> Are they custom? >>> >>> Were you asking me? My parts were Molex 73415-3980, >>>http://www.molex.com/molex/products/datasheet.jsp?part=active/0734153980_RF_COAX_CONNECTORS.xml >> >> Nice, but my picoseconds wouldn't make it around the bends. >> Calling this a "75 ohm" connector is interesting too. > > Yes, it's 75 ohms. As slow as 2ns rise/fall time is fine > for a pulse picker, although one does want less drift and > variation than that.CMOS has a terrible positive delay TC, many ps per degree C per gate. In a circuit like yours, that could be mostly compensated out with an LM45 or something. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●June 7, 20162016-06-07
On 06/06/2016 09:57 PM, John Larkin wrote:> On Mon, 6 Jun 2016 12:56:54 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 06/06/2016 12:49 PM, John Larkin wrote: >>> On Mon, 6 Jun 2016 12:23:26 -0400, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> On 06/06/2016 12:19 PM, John Larkin wrote: >>>>> On 6 Jun 2016 08:34:47 -0700, Winfield Hill <hill@rowland.harvard.edu> >>>>> wrote: >>>>> >>>>>> George Herold wrote... >>>>>>> Winfield Hill wrote: >>>>>>>> Phil Hobbs wrote... >>>>>>>>> >>>>>>>>> Something with a nice bulkhead thread that transfers the >>>>>>>>> stress to the box instead of the solder joints is very >>>>>>>>> reassuring. (You do have to let the board move around a bit.) >>>>>>>> >>>>>>>> As I mentioned, the ones I'm using have such a feature, >>>>>>>> and the wire is soldered. BTW, I added a pic of the pcb, >>>>>>>> panel and connectors from the back to the dropbox folder. >>>>>>> >>>>>>> Oh, what are those BNC "header" type things? >>>>>>> Are they custom? >>>>>> >>>>>> Were you asking me? My parts were Molex 73415-3980, >>>>>> http://www.molex.com/molex/products/datasheet.jsp?part=active/0734153980_RF_COAX_CONNECTORS.xml >>>>> >>>>> Nice, but my picoseconds wouldn't make it around the bends. >>>>> >>>>> Calling this a "75 ohm" connector is interesting too. >>>>> >>>>> >>>> >>>> Probably more about the pin diameter than anything. >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> BNCs are good to roughly 3 GHz, 100 ps maybe, so those connectors >>> might be OK. Maybe a little inductive. >>> >>> We don't use BNCs on anything faster than about 500 ps. A good BNC is >>> actually pretty impressive at high frequencies. >> >> A lot of my stuff goes on optical tables, where BNC is *de rigueur*, >> being both traditional and very practical, even for low frequency stuff. >> >> For use inside larger systems, I've been designing in a lot of >> Displayport connectors lately. You get four lanes of shielded twisted >> pair plus control wires, it has a retaining catch so it doesn't jiggle >> loose, and it's cheap like borscht. >> > > HDMI are interesting, too. > >I've used them as well--they're nearly interchangeable, but HDMI has no latch, so it's liable to vibrate loose unless you tie it down somehow. Displayport is especially nice that way. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
