> 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
Reply by John Larkin●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 John Larkin●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 krw●June 6, 20162016-06-06
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.
Reply by John Larkin●June 6, 20162016-06-06
On 5 Jun 2016 12:31:35 -0700, Winfield Hill <hill@rowland.harvard.edu>
wrote:
>Some reading for a lazy Sunday afternoon.
>
>A typical femto-second laser might give 65kW 0.1ps light pulses at a rate of
>80MHz. But some applications can't handle a powerful light pulse every 12.5ns,
>for example fluorescence-lifetime measurements (we don't want to re-excite any
>molecules before achieving 100% decay). The solution is to add a light
>modulator, and run it from a pulse-picker. The picker should have adjustable
>pulse width and delay or phase, to exactly enable the modulator in the middle of
>a selected pulse. Pulse picker synchronizers typically cost $6000, but I
>figured it shouldn't be hard to design and make them for say, under $100.
$6000 sounds extreme.
Our little delay generator can do pulse picking. It has an input
divider and N-of-M burst triggering.
http://www.highlandtechnology.com/DSS/T560DS.shtml
Some pulse pickers need more outputs, for firing multiple Pockels
cells and stuff. Sometimes we don't pick the next pulse, but one
several pulses out in the train, so we need a semi-complex set of
pretty accurate delay+width outputs.
Closer to the geometric mean of $100 and $6000.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Reply by John Larkin●June 6, 20162016-06-06
On Mon, 6 Jun 2016 14:39:13 -0700 (PDT), klaus.kragelund@gmail.com
wrote:
>On Sunday, 5 June 2016 21:31:43 UTC+2, Winfield Hill wrote:
>> Some reading for a lazy Sunday afternoon.
>>
>> A typical femto-second laser might give 65kW 0.1ps light pulses at a rate of
>> 80MHz. But some applications can't handle a powerful light pulse every 12.5ns,
>> for example fluorescence-lifetime measurements (we don't want to re-excite any
>> molecules before achieving 100% decay). The solution is to add a light
>> modulator, and run it from a pulse-picker. The picker should have adjustable
>> pulse width and delay or phase, to exactly enable the modulator in the middle of
>> a selected pulse. Pulse picker synchronizers typically cost $6000, but I
>> figured it shouldn't be hard to design and make them for say, under $100.
>>
>> Here's my recently-completed RIS-761 divide-by-N pulse picker.
>> https://www.dropbox.com/sh/ofzc5xo880ne8ag/AACSmMZdooCPf57UT950R37ea?dl=0
>>
>> It combines fast logic gates with a few analog-circuit functions to provide
>> synchronization and shaping. In practice the phase and width settings would
>> only be made once per laser setup, so knobs are not provided. The delay / phase
>> is adjustable over a 20ns range, more than needed, and the width from 5 to 18ns.
>> The 99cm pcb slides into a Hammond 2x4x4-inch extruded box, which is the most
>> expensive component. Parson my poor cell-phone photo quality.
>>
>Nice idea and thanks for sharing
>
>Just a question, you are paralleling the 74LVC2G04 inverters. Is that safe to do?
>
>Cheers
>
>Klaus
We parallel three or even six gates to get more drive. Seems to work.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Reply by Winfield Hill●June 6, 20162016-06-06
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.
--
Thanks,
- Win
Reply by Winfield Hill●June 6, 20162016-06-06
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. The short distance of impedance
mismatch isn't even noticeable with a 500MHz scope. I'm
happy to be able to double the number of BNCs onboard.
--
Thanks,
- Win
Reply by ●June 6, 20162016-06-06
On Sunday, 5 June 2016 21:31:43 UTC+2, Winfield Hill wrote:
> Some reading for a lazy Sunday afternoon.
>
> A typical femto-second laser might give 65kW 0.1ps light pulses at a rate of
> 80MHz. But some applications can't handle a powerful light pulse every 12.5ns,
> for example fluorescence-lifetime measurements (we don't want to re-excite any
> molecules before achieving 100% decay). The solution is to add a light
> modulator, and run it from a pulse-picker. The picker should have adjustable
> pulse width and delay or phase, to exactly enable the modulator in the middle of
> a selected pulse. Pulse picker synchronizers typically cost $6000, but I
> figured it shouldn't be hard to design and make them for say, under $100.
>
> Here's my recently-completed RIS-761 divide-by-N pulse picker.
> https://www.dropbox.com/sh/ofzc5xo880ne8ag/AACSmMZdooCPf57UT950R37ea?dl=0
>
> It combines fast logic gates with a few analog-circuit functions to provide
> synchronization and shaping. In practice the phase and width settings would
> only be made once per laser setup, so knobs are not provided. The delay / phase
> is adjustable over a 20ns range, more than needed, and the width from 5 to 18ns.
> The 99cm pcb slides into a Hammond 2x4x4-inch extruded box, which is the most
> expensive component. Parson my poor cell-phone photo quality.
>
Nice idea and thanks for sharing
Just a question, you are paralleling the 74LVC2G04 inverters. Is that safe to do?
Cheers
Klaus
Reply by Phil Hobbs●June 6, 20162016-06-06
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.
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