digital clocks

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Bert Russell
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Joined: Tue May 06, 2003 1:01 am
Location: Bellingham, WA.
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digital clocks

Post by Bert Russell » Sun Mar 20, 2005 11:20 am

Hello all. My storage drawer for digital IC's has a small number of CD4511B chips in Plastic Dip's. Can anyone tell me how the ting is supposed to be connected to feed a digital clock? The pins that feed the 7 segments are well marked on the Manufacturers spec sheet, but it does not say how it blanks the unused digits. I assume it's by disconnecting the return path for any digit not used at any given moment. But nowhere do I see any indication of what to connect where for the returns.
Thank you. Bert Russell

Enzo
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Location: Lansing, Michigan, USA
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Re: digital clocks

Post by Enzo » Sun Mar 20, 2005 12:05 pm

The 4511 is not a clock chip, it is a BCD to 7 segment decoder. It is specialized to include driver outputs and the input latches. It drives just one display at a time. To use it on more than one requires some outside device stobing the separate digits. It does not participate in leaving digits blank directly. Your system must tell it to blank while the unwanted digit is strobed.<p>All this chip does is put the number you latch into it on the seven segment display. It has no way to know if it is displaying a leading zero or not. It is up to the thing controlling it to decide to suppress leading zeroes or not.<p>If you bring pin 4 low, that blanks the display. That is the blanking pin. By the way, pin 3 is the lamp test, so bringing it low lights all the segments. Think of that as an "8." Pin 5 is the latch enable which helps you to drive multiple displays from one set of BCD lines.<p>So your display needs one set of BCD numbers plus a stobe for each digit.

Bert Russell
Posts: 7
Joined: Tue May 06, 2003 1:01 am
Location: Bellingham, WA.
Contact:

Re: digital clocks

Post by Bert Russell » Sun Mar 20, 2005 1:40 pm

Thank you, Enzo. No I have more work to do.

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