word recognizers


snapdiode <snapdiode@...>
 

I see these things on ebay but the prices are out of whack. Is there a reason these are expensive, eg A6701?

I like the pretty colors and would like to have one but not for $250 US..


 

The A6701 specifically requires a custom power supply and cable that are near unobtainium, as well as the customary probe leads and grabbers, which drives the price up (I guess?). There's been one on the auction site for months that is only $100, but has no power supply or cables. There is a second listing that includes cables and grabbers (but still no power supply itself) for $202 (discounted from $270).

I suppose that they are useful for digital work, but they seem like only half of an actual logic analyzer.

They do look nice, though, with all the switches. I have the much less impressive looking P6407 Word Recognizer Probe for my 2465, but I haven't used it.

-- Jeff Dutky


Roy Thistle
 

On Tue, Oct 12, 2021 at 09:40 AM, Jeff Dutky wrote:


I suppose that they are useful for digital work
P6407 probe uses circuitry in the 2465 to enable word triggering.
As I understand it A6701 is stand alone and can be used to trigger a general purpose scope, of sufficient bandwidth, on a word
On the A6701 ... why Tek had to use a 16V power supply (compatible with RS232?) [P6407 uses 5V, from the 2465]... and why they had to use those expensive 12 pin circular connectors... don't know (Marketing was in on it?)
Anyway... not that useful for digital work IMO, unless the complete A6701 was free, and you wanted to start another retro YouTube channel for IMSAI 8080, of the PDP-1, in your basement.
Probably more useful for clueless (or unscrupulous) sellers on that "auction site" to raise vacation funds, from sales to the equally clueless, or the obsessed, or both.
Even if you do have a PDP-1 in the basement, you can sometimes snag an old HP MSO (even with grabbers, pods, and cables), for a little more cash, if you want to go the MSO versus logic analyser route.

--
Roy Thistle


snapdiode <snapdiode@...>
 

No work. Pretty. Want.


 

snapdiode wrote:

No work. Pretty. Want.
Same, but I have contented myself with a 7D01 (has the same miniature toggle switches).

I asked a question on the list, maybe 6 months ago, about using custom circuitry to generate trigger signals for scopes, based partly on seeing a P6406 word recognizer probe on eBay. The resulting discussion was a bit wide ranging, though it did mention word recognizers at first. You specifically replied saying that a "74LS688 can be used to make a word recognizer," which is almost exactly what I was imagining at the time. The thread was titled "Historical Analog Scope Triggering Techniques" and I was specifically envisioning a portable scope like the 465 or 475, as I knew nothing about the modular scopes at the time.

-- Jeff Dutky


snapdiode <snapdiode@...>
 

More words I recognize: "This listing has ended". If someone here bought it I shake my tiny fist at you! And commend you for having a larger toy budget.


Harvey White
 

Most of the scope type word recognizers were meant to decode 8 (or so) bits of address or digital conditions, then provide a trigger edge to an analog scope.  (i.e. when address 231 is reached, trigger the scope).

Logic wise, you have an 8 bit switch providing a digital word to a magnitude comparator (you only need the = output unless you want to be fancy).  The magnetude comparator can be a bunch of exclusive or's with the outputs (when 1) going to a 74LS30 or equivalent.  Check the logic, though for proper signals.

You could also make one out of a CPLD with level shifter input buffers, or use LM339 comparators if the logic can be a bit slow.

I have one for my 2430A scope.  I never have used it.

Harvey

On 10/12/2021 5:28 PM, Jeff Dutky wrote:
snapdiode wrote:
No work. Pretty. Want.
Same, but I have contented myself with a 7D01 (has the same miniature toggle switches).

I asked a question on the list, maybe 6 months ago, about using custom circuitry to generate trigger signals for scopes, based partly on seeing a P6406 word recognizer probe on eBay. The resulting discussion was a bit wide ranging, though it did mention word recognizers at first. You specifically replied saying that a "74LS688 can be used to make a word recognizer," which is almost exactly what I was imagining at the time. The thread was titled "Historical Analog Scope Triggering Techniques" and I was specifically envisioning a portable scope like the 465 or 475, as I knew nothing about the modular scopes at the time.

-- Jeff Dutky





 

snapdiode wrote:

More words I recognize: "This listing has ended".
it had the power cable, and they discounted it. You can still buy the other one (sans cables, but with the case) for "only" $103, if you just want a shelf queen.

(I am NOT the seller. I've been eyeing that same unit for almost a year, and always held off because it doesn't have the power supply or power cable, and TekWiki doesn't have a PDF of the manual)

-- Jeff Dutky