Back in '98, Electronic Design had a design tip on a homemade time domain reflectometer. I'd sort of like to build one up, but this one used the 74AC series of logic and the best it would do is a rise time of 5 ns. I'm only needing something to go 50 feet (15m) or so, but would like glitch resolution to a couple of inches. Is there a logic family readily available that can do 500ps to 1ns or so?Jim

DS90C402, 650 ps maybe, fairly clean step. I could post a pic to abse.MC10EP89 is a lot faster but the ecl levels are a bit of a nuisance. What sort of scope do you have?John

Fast rise time?

Jun 01, 2006 42 Replies

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John Larkin 20 years ago

James,

I have some IMS 150 Meg 0805's in stock if ever you need some.

John

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dagmargoodboat 20 years ago

Noted, most generous, and thanks, but I'm set -- I've cobbled together a couple 22M for present purposes.

Part of the appeal of Farnell's $0.20 surface mount units is the prospect of making inexpensive gadgets (inexpensive a la Joerg, e.g.), gadgets which would be impractical with multi-buck resistors.

Best Regards, James

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Chris Jones 20 years ago

Perhaps a comparator: Analog ADCMP572 / 573 / 580 / 581 / 582 ???

Next you need to design the sampler for the receiver. That'd work really nicely as a 0.18u CMOS ASIC... I wonder if some one makes them.

Chris

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