Debouncing....at About 1Mhz

Nov 01, 2007 300 Replies

John Larkin snipped-for-privacy@highNOTlandTHIStechnologyPART.com posted to sci.electronics.design:

You are welcome to any thoughts you want. Please remember that the "input" is coming from a reasonably fast comparator as it is.

John Larkin snipped-for-privacy@highNOTlandTHIStechnologyPART.com posted to sci.electronics.design:

I think i see where you went, that is kind of slick. Has to be a non inverting ST.

Fred Bloggs snipped-for-privacy@nospam.com posted to sci.electronics.design:

I think they made the original, i used some knock off a mere 20 years ago. It did the job and was cheap. If i was trying to make a real design today i would be looking for an AHCT equivalent.

John Larkin snipped-for-privacy@highNOTlandTHIStechnologyPART.com posted to sci.electronics.design:

Maybe, maybe not. Have you carefully analyzed all the propagation delays? What happens with a fast AHCT equivalent (is the '221 close enough?)?

John Larkin snipped-for-privacy@highNOTlandTHIStechnologyPART.com posted to sci.electronics.design:

Would not work in this case. As previously stated signal is from a comparator.

What difference would that make? The input is a logic level, and its time behavior has been defined.

Yes, there is a simple fix that allows reliable operation with real-world cmos schmitts. It's sort of obvious.

John

formatting link

Best regards, Spehro Pefhany

"it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com

Neato..a differentiator warping the signal into the hysteretic levels... Nope...I didn't guess that one.

One wild idea I had was to try and use a 4.5nS LT latching comparator in some fashion.. But nahhh.. (No I'm not affiliated with LT in anyway..)

D from BC

I'll give you simple, but the other descriptors are in your dreams. I will not get into the details of the inferiority of your 'design' other than to say even a chimp would know that mixing RC's into a first occurrence event detector makes no sense.

Just more of your delusional fantasies...must be the Lipitor has corrected your testosterone deficiency, how does it feel to be able to grow a mustache for the first time in your life...

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Neato! A non-repeatable "solution" ;-)

...Jim Thompson

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave

Clearly it needs some delay. Maybe I should have used Jim's magical "Delay" black box.

I don't suppose you noticed that the RC drives the D pin of the flop. Hell, you obviously don't understand the circuit at all.

So design and post something and quit whining.

I've had one since I was 19. I was doing presentations to aerospace companies, like Lockheed and Boeing, and I just looked too young. The moustache helped a little. We got the contracts, so I suppose it did.

John

Hey, Jim is actually Fred in disguise!

John

Waveforms that only droop the part of the waveform you WANT to droop (trying to make your case) don't quite do that in the real world.

...Jim Thompson

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave

Circuits process waveforms the way I want them to, because I design them that way.

Are you suggesting that I don't understand how RC circuits respond to waveforms? The only alternative seems to be that you don't. So you must be Fred, qed.

John

[snip]

Funny, your circuit doesn't produce waveforms exactly as you sketched them.

Put some numbers on a real circuit, post it, and then let the mob evaluate its efficacy.

Or are you chicken ?:-)

...Jim Thompson

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave

Of course not. That's why they call it a "sketch." And since the component values aren't specified, it couldn't do anything "exactly."

So you *don't* understand it! That's interesting.

John

[snip]

Your recent responses have become of such a subterfuge level I have to conclude you're a leftist weenie. Bye!

...Jim Thompson

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave

Well, either you see it, or you don't. I guess you don't.

John

Oh, I see it. It's just part of your leftist weenie persona to duck by claiming I don't understand.

Your circuit's Thompson Reliability/Repeatability Rating == 0

...Jim Thompson

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave

If you do understand how it works, why are you challenging me to prove that it works?

It does work. And, as I noted when I posted it, it was a way to get the prop delay down to 1. And as I also noted, it has constraints that would lead me to prefer my first circuit.

I suppose all that makes me a leftist weenie.

You know, in any given half-hour, me and one of my guys, with a whiteboard, may come up with 50 interesting circuits. Most are flawed in some way, many are plain goofy, but the process usually leads to something that's both elegant and reliable. Some people just poison a process like this. People like that should be airline mechanics or something, where eveything must be exactly the same, by the book, every time.

John

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