lansd@utgpu.UUCP (04/23/87)
I would like to build a homebrew logic analyzer using several
parallel banks of ram chips to provide a wide bandwidth.
What I would like to know is:
1) What input conditioning do the expensive logic analyzers
perform on the input (in particular, which gate types).
2) Have there been any electronic articles published lately
with 'do-it-yourself' logic analyzer projects? (I remember
Radio Electronics or Popular Electronics had one around 1977).
One question not pertaining to this... does anyone know of a
25-100 mhz(!) cheap 8 bit flash converter? I have a paper in front of
me that describes a 25mhz version from ITT for $20, but this is somewhat
slow for my application.curtis@cit-vax.Caltech.Edu (shan Curtis) (04/26/87)
I would also like to receive information on this. Thank you. Curtis
keith@amc.UUCP (Keith Payea) (04/29/87)
I used to work for Paratronics, the outfit that published that article in Popular Electronics about the home-brew logic analyzer. They used a variety of approaches for signal buffering, depending on the expense of the unit :-)... Some of them were good to a few hundred MHz, and were adjustable for both ECL and TTL levels (i.e. had a threshold level adjustable from about -5 to +5). For a simple project like you decribe, I would just use 74HCT244's with series current limit resistors for some protection. 10Kohms would protect the circuit from connection to 110V, and still provide enough current at TTL thresholds to give good levels out. If you have the bucks, want the speed, and can locate them, use 74ACT244's instead. Good Luck. Keith Payea Applied Microsystems Corp. P.O. Box C-1002 Redmond, WA 98073-1002 (206)882-2000 ...ihnp4!uw-beaver!tikal!amc!keith "The only things which separates us from the animals are mindless superstition and pointless ritual." Latka Gravas