BCD Counter

Apr 27, 2006 13 Replies
M

After getting flamed for not cross posting last time, Ive learned the error of my ways.



With some great help, I was able to build the complete circuit.



I just had to connect two seven segment displays to it and make it able to count up to 99.



I did that but I havent uploaded it as it doesnt look neat and would be a pain to look at.



Now, during play the counter counts up at a regular pace. Then if I press stop it resets or if I press pause it stops the counter.



The thing I cant seem to get is how to get Fast Forward to work. I need to make the counter go faster and have been unable to do that.



The counter counts up using a bcd decade counter. As mentioned it counts fine, but I cant seem to figure out how to make it go faster.



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M

sorry... I wasnt able to post the image correctly.

You can simply click on on of the urls to view what I have done so far

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K

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I don't know what circuit you're using for your clock display, but if you use the fast forward output from the circuit you've linked to you can use it to gate either 'normal' speed clock pulses to your display circuit or higher-speed clock pulses (from further up the divider chain).

Ken

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M

Ive uploaded the image of the clock display now.

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Right now it counts up automatically to 9 and then resets.

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K

Where are you getting your clock from? Use the fast forward signal to select a higher clock speed.

Ken

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M

the clock (squiggly line) is just there to represent where the input would come from.

How do I select a higher clock speed ?

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L

This is a mental exercise, no one would use this kind of circuit today. So just insert a binary divider and specify a faster clock. Then select the raw clock or the output of the divider.

I once had to repair a TEAC reel to reel tape deck with logic like this using about a dozen relays. After attempting to trace the logic problem for some time, I concluded that the circuit was not defective, but that the signal simply got lost trying to find its way thru it... :)

Luhan Monat (luhanxmonat-at-yahoo^dot^com)

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"Reality: what a concept!"

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D

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Just a few observations about your circuit. You don't show any pullup or pulldown resistors on the gate and flipflop inputs. Are you using any? What technology are you using for your ICs (TTL/LSTTL/CMOS, etc.)? I recommend pullup resistors on every input that might float while any of the switches are not being pushed. Floating inputs can cause all kinds of grief.

The fast-forward circuit needs a faster clock than the normal speed counter circuit. Find a faster clock source for that counter.

Dave M MasonDG44 at comcast dot net (Just substitute the appropriate characters in the address) They call it PMS because Mad Cow Disease was already taken.
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J

I\'ve posted a front end for your counter circuit on alt.binaries.schematics.electronic under "BCD counter (from seb)."
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M

sry for my noobness, but I dont know how to access alt.binaries.schematics.electronic

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J

Get a USENET provider. But, I had mercy on you. Look in your inbox.
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R

It's not noobness - it's from posting at googlegroups. (BTW, it's worth noting that you _do_ quote context, and you _do_ bottom-post - these are _good_ things. :-) )

But, as John said, get a real news server - ask your ISP, they probably already have one, and will be happy to teach you to access it.

Good Luck! Rich

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