I fixed my 4 digit counter circuit (The Great Multi-Digit Saga: Part 3)
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- Опубліковано 19 сер 2024
- Talking about the problems I had fixing my 4 digit electronic counter circuit.
This turned into a multi-part miniseries:
Part 1: • Upgrading the counter ...
Part 2: • I thought 4 digits wou...
Part 3: (you are here)
-- Links
HLF SN74LS160N Data Sheet: hlf-ic.cn/uploa...
HLF SN74LS162N Data Sheet: hlf-ic.cn/uploa...
(Possibly wrong!)
Texas Instruments SN74LS192 Data Sheet: www.ti.com/lit...
HLF SN74LS48N Data Sheet: hlf-ic.cn/uploa...
XLITX 5161AS LED Display Data Sheet: www.xlitx.com/d...
-- Stuff
Timers/Op-Amps IC Kit: amzn.to/3Hqysz0
74LS TTL IC Kit: amzn.to/40WH75c
Multimeter: amzn.to/49PUg45
Power supply: amzn.to/3uAYxIE
Breadboard kit: amzn.to/3MYwfho
7 Segment Display: amzn.to/3viAu1l
Logic Probe: amzn.to/3SfDRz4
Antistatic mat: amzn.to/49RhcQi
My Wife's Books: amzn.to/47yt9Ji
(Maybe you and/or someone you know will like them!)
An idea for a next project that would still use most of what you have already in place is to count like a clock 0->59 on the right and 0->24 on the left side counters, it'll requiere resetting while you count and some logic for the increments outside of 9
I know what you mean about taking stuff apart, I've got a really great circuit sitting on my bench that I don't want to take apart before I make a video to remember it by!
I'd really like to see you get an oscilloscope and watch the voltages. So we could watch what is causing the bounce. Even without it though it's interesting to watch.
I took a look at the datasheet for that INS8073, it is certainly an interesting chip! I think you should have no problems hooking it up, For SRAM, I think you should get a AS6C1008 instead of those chips you have, as they're 1 bit wide each (each has a single data line), the AS6C1008 is a 128K chip, which will allow you to move on to a 6502 or a Z80 in the future. The INS8073 certainly is interesting, and it has an UART onboard, which means that you won't have to worry about that, still, hooking it up will teach you the basics of memory address decoding. For a fun project that will lead up to hooking up the cpu, you could use those SRAM chips you have to store numbers, and display them on the seven segment displays in order!
It shouldn’t be too hard to make a simple synchronous reset circuit from an asynchronous pulse with a D type flip flop that has an asynchronous reset. Something like a 74ls74 would work but any D type buffer with a reset would work.
Tie the D input high (and if you are using a 7474 the set line high too). Use the same clock as your counter circuit to the flip flop and then use whatever reset circuit you like (an RC circuit for power up reset and/or a switch to pull the reset line low). The output of the flip flop then goes to your counter resets. The flip flop will go low when the reset is used and will remain low until the next clock pulse when everything should get reset.
Do hou have any small bypass caps that you can put acrross tbr power snd ground rails close to the vcc pins of your ics. Minor power fluctuations can have unusual effects that can be hard to debug.
No, he doesn't. I raised that issue in his previous video. The breadboard with the counters should have not only local decoupling caps but also a bulk cap of 10µF or more.
My suspicion is that the failure was due either to lack of decoupling for the counters, or, more likely I think, lack of decoupling for the 555. I had recommended he try debugging using his debounced pushbutton switch instead of the 555, since that would, among other things, allow determination of whether or not events were happening on the "wrong" edge of the clock.
555s do have nominally TTL-compatible output, but is isn't what I'd call particularly "clean." Without local decoupling it can be downright ugly.
People, CMOS is far superior to TTL. Trust me.