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IndiJones
Joined: 13 Aug 2001
Posts: 157
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 02 Nov 2001 4:18 |
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| I need to design a digital circuit that will output logic 1 and lit an LED when the input analog voltage is within a certain range (say 2-5 volt) and will output logic 0 elsewhere. A schematic would be very helpful. Thanks in advance!
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Alexg
Joined: 14 May 2001
Posts: 51
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| 02 Nov 2001 4:29 |
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What you need is called a "window comparator". Follows a link to one of many many ways of doing it. Do a search with windows comparator and you will find a lot of different circuits to opt from.
http://w*w.acroname.com/robotics/info/ideas/window/window.html
Best regards,
Alexg
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sigint
Joined: 01 Jan 1970
Posts: 1010
Helped: 14
Location: State of total confusion
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| 02 Nov 2001 6:02 |
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Use a window comparator for indication only, not for voltage control - whwn used for control it will always oscillate.
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MITSUKO
Joined: 06 Jun 2001
Posts: 49
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| 04 Nov 2001 21:07 |
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I think the chip you need is
TCA965 , by siemens if i'm not mistaking .
You can set the lower and higher trippoint and it gives you a signal inside window or without to high or without to low .
I must have a data sheet here somewhere , i'll see if i can find it .
Mitsuko
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sigint
Joined: 01 Jan 1970
Posts: 1010
Helped: 14
Location: State of total confusion
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| 04 Nov 2001 22:28 |
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| LM324
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IndiJones
Joined: 13 Aug 2001
Posts: 157
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| 05 Nov 2001 3:39 |
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| Thanks! Any schematic would be very helpful.
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sigint
Joined: 01 Jan 1970
Posts: 1010
Helped: 14
Location: State of total confusion
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| 05 Nov 2001 7:06 |
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Check out Poptronix magazine they recently, within the last couple of years, had a column that addressed comparator usage. If that doesn't prove fruitful I think I have a couple of old designs I could share.
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unkarc
Joined: 28 Apr 2001
Posts: 280
Helped: 36
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| 05 Nov 2001 13:44 |
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Hi Indijones,
If you do not insist on a digital circuit schematics to solve your problem, then check the following "analog" schematics: http://www.mitedu.freeserve.co.uk/Circuits/Switching/comparator.htm
It should work with a "digital" +5V supply as well.
I found it on a circuit schematics "eldorado" at http://www.commlinx.com.au/schematics.htm that was already referred to earlier at this Forum.
Regards
unkarc
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IndiJones
Joined: 13 Aug 2001
Posts: 157
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| 08 Nov 2001 8:20 |
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Thanks! I've done it with LF356N Opamp from National Semiconductor.
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