You may be able to do it with just a comparator, depending on as yet unspecified details. RC on one input means it passes the input signal until a certain time when it locks out. Add diode to discharge when power off.
NT
And four interconnected NAND gates. You forgot them! :-D BTW, your English is excellent. How did you acquire such fluency?
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May be possible, but will it be any simpler than my design - i.e., use fewer parts? And will the output match the input pulses precisely without careful adjustment? I'm always interested in any improved alternative to my own ideas.
Pardon me if I ask dense questions, I'm late to this thread... busy on a modeling project, and haven't follow closely:
Is this a one-time event? Or does, sooner or later, the signal begin from a high?
Seems that it must. ...Jim Thompson
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| James E.Thompson | mens |
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| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
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Thinking outside the box... producing elegant solutions,
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This has been causing some confusion, so let me expand with the full timeline. I had assumed folks would 'just know' but clearly that's not the case.
This would have been so much simpler to illustrate by means of a timing diagram, but sadly I don't have the facility to post such.
a
I don't think a timing diagram is needed, this is clear. The confusion com es from the fact that this is truly a one time event when powered up. Whil e you did "accurately" describe this in your initial post, inaccurate descr iptions are not uncommon and the language you used did not specifically add ress the obvious questions that have been asked. To head off those questio ns you would have needed to know to expect them and to specifically address them initially as you have done now. Heck, the timing diagram posted by P impom has a perfectly good timing diagram, but it still begs the question o f "what happens next?"
Another way to head off the questions might have been to give some context, but that can lead to many more questions, so.... :)
Rick C.
This is exactly as I understood it from the beginning, including
6 and 7. Frankly I'm surprised that there was any confusion.
Register for a free account at Dropbox.com or similar site.
You're obviously smarter than the average bear. ;-)
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1 comparator, 1 R, 1 C.
whether you need to adjust it depends on timings & tolerances. In some apps it won't be critical anyway. Only the OP knows what best suits his unstated requirements.
NT
That is an excellent question. I'm scratching my nut furiously here, because I can *almost* picture a two-transistor solution to this; three at most. And I mean jelly bean BJTs. Sleeping on a problem like this often works for me, but I won't be heading to bed for several hours yet. :-)
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What about setting the threshold?
What about it are you asking? Obviously the comparator's threshold moves analoguely over time, if you know what the specs are for the input signal you can make that work.
NT
*I* am heading for bed. It's getting close to 2:00 AM here. Will check tomorrow to see if you've come up with any bright new idea.
Does "switched on" mean "powered-up"? In that case you would need some method of power-on-reset to ensure that the logic starts in the right state?
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Thinking outside the box... producing elegant solutions,
by understanding what nature is hiding.
"It is not in doing what you like, but in liking what you do that
is the secret of happiness." -James Barrie
Yes.
No. The intervals between resets are *so* long that internal resistances will take care of that (assuming I understand your question correctly...)
OK. I guess you have your problem solved. ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at
Thinking outside the box... producing elegant solutions, by understanding what nature is hiding.
"It is not in doing what you like, but in liking what you do that is the secret of happiness." -James Barrie
Sorry, is that meant to be sarcastic?
Me? Sarcastic ?:-) ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at
Thinking outside the box... producing elegant solutions, by understanding what nature is hiding.
"It is not in doing what you like, but in liking what you do that is the secret of happiness." -James Barrie
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