Subject:
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Re: Polariod Sonar
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Sun, 24 Nov 1996 07:46:07 GMT
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Original-From:
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Richard Vannoy <RICHARDV@nomorespamABAC.COM>
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Viewed:
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1487 times
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> I'm trying to use TTL output of 74 series IC's to signal to INIT. I can't get it to work properly. Here's the deal. When I touch INIT to the 5V bus, the transd
> Looking closely at the TTL output, I found that it drops from 5.149 V to 3.58 V the moment I connect INIT to it. And apparently, it doesn't stay at 5 V long en
Although I teach a digital electronics class based on the 74xx series, I'm certainly no
expert, but here goes anyway...
TTLs seem to have a very low ability to drive anything but minimal loads. Look up
"drivers" in the TTL Data Book. They provide a better output for other devices. We use
them for driving 7-segment LEDs. I suspect that your INIT is drawing too much current
and loading down your 74xx. I'll keep tuned in to see what others can add.
--
Richard T. Vannoy II richardv@abac.com
PO Box 103 Computer Programmer
La Mesa, CA 91944-0103 College Electronics Instructor
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Message has 1 Reply:
 | | Re: Polariod Sonar
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| I think you're right. I used a transistor to drive the INIT with its emmiter and feed the TTL signal to the base. It seems to work fine now. :) You know what's funny, I tried using a CMOS chip (HCT) and it was able to drive the INIT signal. I figure (...) (28 years ago, 28-Nov-96, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | Polariod Sonar
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| Hi, I'm stuck. I'm trying to use TTL output of 74 series IC's to signal to INIT. I can't get it to work properly. Here's the deal. When I touch INIT to the 5V bus, the transducer "chirps". But when I touch INIT to a high level TTL output, it doesn't (...) (28 years ago, 23-Nov-96, to lugnet.robotics.handyboard)
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