Good general purpose binary counting IC

Thread Starter

uraniumhexoflorite

Joined Oct 23, 2016
204
I've been working on designing a binary clock and now that it's designed, I'm ready to build it. Only problem is that I don't have enough ICs. I was wondering which binary counting ICs people recommend. I want one that has a carry feature (chain 2 or more together). Thanks for advice. :)
 

AnalogKid

Joined Aug 1, 2013
8,138
The CD4017 is not a binary counter. In fact, it isn't a counter at all. Internally it is s shift register with decoding gates.

Separate from that, the hardest part about a digital clock is the setting mechanism. The reason so many digital clocks can be set in one direction only, so that if you overshoot the correct time you have to cycle through 24 hours, is that it makes the setting circuit so simple - just bypass part of the seconds pre-divider and the clock runs faster. Being able to set by going either forwards or backwards requires bi-directional counter chips, parts that are more expensive and more complicated. So, how simple or convenient (can't be both) do you want the set procedure to be?

Separate from that, congrats on doing a discrete design rather that something based on a PIC or Arduino. Can you share your schematic?

ak
 

MrChips

Joined Oct 2, 2009
19,382
Every binary counter begins with a flip-flop.
If you have any number of flip-flops you can make a binary counter.

Every binary counter has a carry feature. You can chain any and every binary counter.
 

Bernard

Joined Aug 7, 2008
5,284
Back in the early 1970s I designed & built a digital clock with bunches of 7490's & 7493's & now same functions
are available in CMOS as 74C90. /10 & 74C93, /12.
 

Thread Starter

uraniumhexoflorite

Joined Oct 23, 2016
204
I have been experimanting with two 74LS169s. While they do have up and down counting, I'm less than satisfied with their carry feature. The carry pin is high by default which causes the 2nd chip to start at 1 instead of 0. I can send you the schematic of the circuit a bit later.
 

MrChips

Joined Oct 2, 2009
19,382
I have been experimanting with two 74LS169s. While they do have up and down counting, I'm less than satisfied with their carry feature. The carry pin is high by default which causes the 2nd chip to start at 1 instead of 0. I can send you the schematic of the circuit a bit later.
74LS169 is a synchronous counter, not a ripple counter. Know the difference.
Read the 74LS169 data sheet very carefully.

To cascade two or more stages, connect all CLK inputs together.
Connect /ENT to LOW.
Connect /RCO of the first stage to /ENP the next stage.
 

MrChips

Joined Oct 2, 2009
19,382
Depending on what you are trying to do, you may also want to look at 74LS160 and 74LS161

and 74LS90, 74LS92, 74LS93.

Are you sure you want chips from the 74LS family?
There are other families in the 74xx series to choose from
as well as CMOS 4000 series.
 

Thread Starter

uraniumhexoflorite

Joined Oct 23, 2016
204
I'm open to using any chip as long as it gets the job done. Here is a picture of the circuit that will count seconds. The circuit for minutes is the same as the one in the dashed box except that the minute gets its clock input from the output of the seconds circuit that is labeled "to minute counter" instead of the 555. The circuit for counting hours would be very similar but with one sn74ls169 because it only would need to count to 12.
 

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dl324

Joined Mar 30, 2015
9,121
Here is a picture of the circuit that will count seconds.
This is one of the times when I'd ignore the left-to-right, top-to-bottom flow guideline in the interest of readability:
upload_2017-9-22_12-0-3.png
You say you're using LS169, but you show a reset input instead of U/D#. You also don't show how LD, ENT, and ENP are connected. The pulldown resistors on CLK, CLR, and RCO are unnecessary and the value isn't appropriate for LS TTL if they were.

I used LS160 because my schematic editor didn't have the binary version.

Here's a 24 hour up/down clock I simulated for someone last year. I used LS190 because it's the only counter in my version of Multisim.
upload_2017-9-22_12-9-49.png
 

ScottWang

Joined Aug 23, 2012
6,829
When the input of LSxx logic gate connects to another output of LSxx logic gate, no needs to add any pull down resistor as Dennis already mentioned, if the input of LSxx logic gate connects to a switch and +5Vcc and then the input needs to add a pull down resistor as 330Ω, if the input of LSxx logic gate connects to a switch and Gnd and then the input needs to add a pull high resistor as 1K~33K.

You can see the internal structure of LSxx logic gate below, the pull down resistor you added to the input circuit will be as a voltage divider, so you can't add a high values resistor when you need to add the pull down resistor, otherwise you can't get a logic low, but if you need to add the pull high resistor then it won't affects the input circuit too much.

74LS04_InternalStructure_TI.png
 
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