On 01/02/17 11:48, tom wrote:> "John Larkin" <jjlarkinxyxy@highlandtechnology.com> wrote in message > news:17929cpj3lgerjo5mmfnjm0dvbn5ee1i9g@4ax.com... >> Picosecond electronics is fun. If you really want to get into that, >> get a sampling scope from ebay. The investment is low hundreds to low >> thousands of dollars, depending on bandwidth. >> Old Tek and HP manuals are enormously educational. > The Tek 11801/11802 sampling scopes can be had for very low cost.Unfortunately this kind of pricing doesn't apply in Australia. Any good 2nd hand equipment asks silly prices, and US Ebay sellers won't ship to Australia. I have an OR-based reshipper, but the cost to ship something like this is still pretty high.
insane flipflop measurements
Started by ●January 31, 2017
Reply by ●February 2, 20172017-02-02
Reply by ●February 3, 20172017-02-03
On 01/02/2017 09:31, John Larkin wrote:> On Tue, 31 Jan 2017 10:51:11 +0100, Gerhard Hoffmann > <ghf@hoffmann-hochfrequenz.de> wrote: > >> Am 31.01.2017 um 05:08 schrieb John Larkin: >>> >>> >>> I'm doing a fast thing and thought I might go all CMOS, instead of >>> traditional expensive ECL. We have the Fairchild NC7SV74 tiny logic >>> flipflop in stock, 16 cents each. I thought I'd play with one. >>> >>> Here are the rise and fall times at the Q output, 3.3 volt supply: >>> >>> https://dl.dropboxusercontent.com/u/53724080/Parts/Logic/NC7SV74_2.JPG >>> >>> That fall time is amazing, but the rise time is hard to believe. I >>> can't see that I'm doing anything wrong. >>> >>> The clock rise to Q rise prop delay is 0.8 ns. Its temperature >>> coefficient was hard to measure, but it looks like maybe +0.7 ps per >>> degree C. Vcc delay coefficient is so close to zero that it doesn't >>> matter. >>> >>> >> Looks interesting! >> >> This is what I got from a pair of SN74LVC1G04DCKR, 50 Ohm source and >> load terminated, running on 6V, still legal. I wanted acceptable 3V3 >> CMOS levels @ 50R input. >> It varies somewhat from batch to batch. >> >> < >> https://www.flickr.com/photos/137684711@N07/32245910100/in/album-72157662535945536/lightbox/ >>> and left/right >> >> Scope rise time is 145 ps. > > That's pretty clean. > >> >> cheers, Gerhard > > The Onsemi NL37WZ16US buffer is a nice part. Put all three gates in > parallel, run at abs max Vcc, source terminate at maybe 40 ohms, and > it's a vicious sub-ns output driver. > >Gerhard chose his words well when he said 6V was "still legal". Make sure you don't turn up the supply rail too high and forget the source termination resistor or it might become all export-controlled as 3A230. So, if you figure out how to do that without it failing, for goodness sake don't tell me. Likewise if I do it then I will also make sure that I don't tell you how. I wonder whether that is a part of the reason why the datasheet max VCC for a lot of logic parts is 6V or so - (as well as the gate length of the transistors). Imagine the paperwork if it was specified a bit higher.
Reply by ●February 3, 20172017-02-03
On Sat, 4 Feb 2017 01:56:27 +1100, Chris Jones <lugnut808@spam.yahoo.com> wrote:>On 01/02/2017 09:31, John Larkin wrote: >> On Tue, 31 Jan 2017 10:51:11 +0100, Gerhard Hoffmann >> <ghf@hoffmann-hochfrequenz.de> wrote: >> >>> Am 31.01.2017 um 05:08 schrieb John Larkin: >>>> >>>> >>>> I'm doing a fast thing and thought I might go all CMOS, instead of >>>> traditional expensive ECL. We have the Fairchild NC7SV74 tiny logic >>>> flipflop in stock, 16 cents each. I thought I'd play with one. >>>> >>>> Here are the rise and fall times at the Q output, 3.3 volt supply: >>>> >>>> https://dl.dropboxusercontent.com/u/53724080/Parts/Logic/NC7SV74_2.JPG >>>> >>>> That fall time is amazing, but the rise time is hard to believe. I >>>> can't see that I'm doing anything wrong. >>>> >>>> The clock rise to Q rise prop delay is 0.8 ns. Its temperature >>>> coefficient was hard to measure, but it looks like maybe +0.7 ps per >>>> degree C. Vcc delay coefficient is so close to zero that it doesn't >>>> matter. >>>> >>>> >>> Looks interesting! >>> >>> This is what I got from a pair of SN74LVC1G04DCKR, 50 Ohm source and >>> load terminated, running on 6V, still legal. I wanted acceptable 3V3 >>> CMOS levels @ 50R input. >>> It varies somewhat from batch to batch. >>> >>> < >>> https://www.flickr.com/photos/137684711@N07/32245910100/in/album-72157662535945536/lightbox/ >>>> and left/right >>> >>> Scope rise time is 145 ps. >> >> That's pretty clean. >> >>> >>> cheers, Gerhard >> >> The Onsemi NL37WZ16US buffer is a nice part. Put all three gates in >> parallel, run at abs max Vcc, source terminate at maybe 40 ohms, and >> it's a vicious sub-ns output driver. >> >> > >Gerhard chose his words well when he said 6V was "still legal". Make >sure you don't turn up the supply rail too high and forget the source >termination resistor or it might become all export-controlled as 3A230. >So, if you figure out how to do that without it failing, for goodness >sake don't tell me. Likewise if I do it then I will also make sure that >I don't tell you how. > >I wonder whether that is a part of the reason why the datasheet max VCC >for a lot of logic parts is 6V or so - (as well as the gate length of >the transistors). Imagine the paperwork if it was specified a bit higher. >All sorts of export-controlled pulses can be made with 15 cent parts that are made in asia and can be purcased by the reel anywhere in the world. The Onsemi part can't quite make 6 volts into 55 ohms in 500 ps, per 3A230. Not quite! -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●February 19, 20172017-02-19
> The Tek 11801/11802 sampling scopes can be had for very low cost. > > Here is one for $150 plus $111 shipping that is showing errors. The repair > is almost certainly a pair of dead memory NVRAM packages and would run about > $30 to restore. > > http://www.ebay.com/itm/H133984-Tektronix-11802-Digital-Sampling-Oscilloscope-/391662629720?>hash=item5b30e97358:g:1KkAAOSwEzxYQgcdI'm the new owner of that EBay 11802, and they even gave me a partial refund on shipping since I'm in the SF Bay Area. It was exactly as described by the vendor and came very well packed. As suspected, the battery backed RAM had a dead battery, and two chips from Digikey solved that issue. It now passes all the self-test and extended diagnostics. It does seem to have another problem, which I'm researching. It seems to not trigger on any external sources. I also had picked up a SD-22 head for $185, and if I set it to internal triggering, and feed it a half volt square wave, I get some unstable traces at about the right voltage, and I'm assuming they are unstable due to no trigger sync. It does seem like this suggests the SD-22 samples (and even has a 2014 calibration sticker). The enhanced accuracy calibration also fails because it says it didn't trigger. So close, not quite there yet. The trigger problem seem to be neither external nor either delay line triggers work. The calibrator output also seems stuck at a small negative voltage, and the internal clock output seems similar. My current plan is to check some things with a scope, like the the TB card clock and some of the strobe board outputs (as soon as a SMB to BNC adapter comes). It offhand seems like the clock must work, as internal triggering works. I see there is also a trigger selector board which perhaps has an issue. Looking at the block diagram, it seems like there are not that many places that could cause no calibrator and internal clock output, assuming the internal clock really works. Assuming there are no unobtainium parts involved, it may be debuggable down to the chip level. It also had a non-functioning upper dial, which on taking out the two screws for the screen bezel, found a little shaft extension from the upper encoder to the knob that was cracked. I put a little super glue on it and heat shrunk some tubing to restore the squeeze on the end that grips the encoder shaft and it's happy again. Two of the quarter turn fasteners on the top cover are also missing, but whatever. The screen seems clear (monochome) all the buttons seem to work, the "touch" screen works fine, and takes a bit of getting used. No smoke or horrible fan noises. Don't see any critters living in it or any sign there ever were. What's with that Tektronix document about washing you scope with spray water. Making it all squeaky clean would be nice though. I also do have a ultrasonic cleaner and some Branson EC, although the TB board is huge and doubt it fits in the tank. I do have the 11801C lame service manual that's around, which does at least have some block diagrams with look very similar to my 11802. It was certainly exciting that $25 in battery ram chips fixed all the diagnostic errors, but also a bit of a bummer that something else, perhaps not so easy to find and fix is wrong too. It is just amazing to turn that horizontal timebase knob and see the scale go down to 1ps/div, so feel quite motivated to do some serious debugging. I built one of the those Jim WIlliam style avalanche pulse generators, and my 300 Mhz Rigol MSO2302A scope (which I like quite a bit) can't come close to measuring the rise time. This series of scopes also has software running in an environment called Smalltalk, and I just happened to have worked on Smalltalk virtual machine implementations at a Xerox PARC startups offshoot, that disabled debug button is like candy on the other side of a window to me. I see some messages here that 11802 10.x firmware was imaged. Does anybody know if it's downloadable someplace? This one has the 9.x firmware, so I read would not work correctly with a SD-14 head without new firmware. I'm new at resurrecting old test equipment, so it's a fun challenge currently. Would be a bit more fun if Tek had released some real service manuals. Thanks in advance for any help :) Jan
Reply by ●February 19, 20172017-02-19
On 19/02/17 09:08, jcbottorff@gmail.com wrote:>> The Tek 11801/11802 sampling scopes can be had for very low cost. >> >> Here is one for $150 plus $111 shipping that is showing errors. The repair >> is almost certainly a pair of dead memory NVRAM packages and would run about >> $30 to restore. >> >> http://www.ebay.com/itm/H133984-Tektronix-11802-Digital-Sampling-Oscilloscope-/391662629720?>hash=item5b30e97358:g:1KkAAOSwEzxYQgcd> This series of scopes also has software running in an environment called Smalltalk, and I just happened to have worked on Smalltalk virtual machine implementations at a Xerox PARC startups offshoot, that disabled debug button is like candy on the other side of a window to me.Tek also produced some Smalltalk workstations in the mid 80s; it was the second Smalltalk implementation I used, Apple's being the first. Back then it was fun to see how quickly electronic engineers jumped to embed Smalltalk (HP did it too). Doubly so when considering the shenanigans that softies went through to re-cast their procedural code in a very poor version of OOP (anybody unfortunate enough to remember JSP?).> I'm new at resurrecting old test equipment, so it's a fun challenge currently. Would be a bit more fun if Tek had released some real service manuals.I presume you know about the Yahoo TekScopes group.
