Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
Search
counting ic's
|
Nick
hello I am new at this eletronics stuff so talk slow.
I am working tords building a digital clock simple enuff well atleast teh concept was. well my question is I bought some counting ic that I was told would work for a clock and well the story goes I cant get it to count so I am asking for some help. First off the ic's were ordered from digikey the link to the parts pdf info file is ... I took and put + to the vcc at 4.9v and grounded pin 7 so now the ic should have power next I took and put a led in series with 1q0 I think it was and the ground because the output should be high and took and hooked a normaly open button from the + to the 1cp and pushed it which sould of made 1q0 high and turned on the led in all of my theory. Nick Graber NickGraber@... |
|
Jonathan Luthje
Nick,
toggle quoted message
Show quoted text
Without spending a lot of time studying the chip, it looks like a simple 2-stage binary counter ... not sure how you're going to a make a clock out of it but I will leave that up to you. Pin 1 (clock inverted) needs a negative trigger, so hook up your switch to ground and you then should get some action happening on your outputs. I also would suggest to you that you use a transistor drive on the output's if you are driving any more than logic level signals (i.e. driving a LED etc.) the device has a very low current rating on the output and you will potentially destroy something if you try to drive anything directly. Good luck! JOn ----- Original Message -----
From: "Nick" <Nickgraber@...> To: <Electronics_101@...> Sent: Saturday, August 04, 2001 2:45 PM Subject: [Electronics_101] counting ic's hello I am new at this eletronics stuff so talk slow. |
|
Nick
ok well I did that I used a new chip just to make shure everyting is
good and I still cant get it to count. I was wondering are all of the outpst low to start because it is counted 0 so it would have an output of LLLL = 0000 = 0 but when I apply the negitve to the triger for the counter I still get 0000. I am now using 2n3904 transistor to run the led. |
|
Jonathan Luthje
Nick,
toggle quoted message
Show quoted text
Ok, that's cool ... now what you need to do is tie the reset line low (via say a 5k resistor), and tie the clock pin to +Vcc via another say 5k resistor, then pull the clock pin down to low, it should then count per pulse received. It needs a transitional voltage (i.e. needs to go from high to low) to trigger properly. I would also suggest that in your final circuit you tie all output lines to ground via 10k (or thereabouts) resistors. When dealing with logic it is always a good idea (i.e. safe practice) to tie any lines, used or unused, to a particular level. If you want to trigger it, apply 0V to the clock pin without disconnecting the resistor tied to +Vcc, to reset, apply +Vcc to MR1/2, again without disconnecting the resistor tied to ground. Hope this helps! Regards, JOn ----- Original Message -----
From: "Nick" <Nickgraber@...> To: <Electronics_101@...> Sent: Sunday, August 05, 2001 12:13 AM Subject: [Electronics_101] Re: counting ic's ok well I did that I used a new chip just to make shure everyting is |
|
Jonathan Luthje
开云体育Nick,
??? There are probably a thousand or more different ways of making either a
1Hz oscillator or a debounce switch, with a thousand or so different IC's, one
of the simplest methods (to kill two birds with one stone so to speak) would be
to use the LM/NE555 timer IC. And perhaps (although I'm not so sure it would be
accurate enough to make say - a clock) it would even be able to function as a
timebase for your clock. Configure it in monostable (one-shot) mode for a switch
debouncer or astable (multivibrator) mode for a timebase.
?
Come to think of it, I may have been initially
wrong with my "how you are going to make a clock with those I don't know"
statement. Come to think of it, it probably wouldn't be all that difficult. If
you do it in the way you describe, it is entirely possible, although perhaps not
all that accurate, using the public power supply (which isn't known to be
absolutely spot on, but I guess you can always add another timebase later if
need be.
?
Yes, you just need to feed low voltage un-rectified
AC (i.e. 60Hz) to the clock pin of the counters and feed the corresponding
outputs into perhaps some AND gates (if the binary value needed uses more than
one bit) which feed into the clock pin of some more counters, and feed the
output of the digit-counters into some binary-to-BCD converters and then into
some LED 7-seg display units. It can be done ... perhaps with a lot of chips,
but it can be done.
?
There is loads of info on 555 timers about the
place, but if you come up?blank ... post another message and I will post up
some suggestions for circuits.
?
?
Let me know how you get on,
?
?
JOn ?
?
? ----- Original Message -----
|
|
Nick Graber
开云体育ok first of all I would like to thank you for your
help how you could tell it had to go from low to high I have no clue Iv been
trigering it with a micro button but it seems to skip some binary number like 1
is hard to get it to go to do you have a simple ocilator I could use to triger
it at about 1hz or less or a way to make the button less sensitive so it doesent
skip.
this chip was bought with 5 others being told I
could make a clock with this chip by dividing a 60hz input by 10 and then 6 to
make the second and so on is that posible with this chip or do I need somthing
different?
Nick Graber
? |
|
Jonathan Luthje
开云体育That's the easy bit - just feed the 60Hz into the
clock, then count up to binary 10 (divide by 10), and feed binary bits used to
make 10 (0101), into the inputs of a
dual-input?AND gate IC, and?feed the output of the AND gate into the
reset of that counter. You can also use the AND gate output as a clock pulse,
although since you are using a negative edge trigger you may have to use NAND or
inverted AND gates.
?
Does that make sense?
?
?
JOn ?
|
|
Hi Nick (and friends)
Following the thread, I see several different parts of the circuit being described, but all on the right track. First, to correct a typo in one of the other replies, 10(base10) in binary should be 1010 (not 0101) a six would be 0110. Decoding that for divide by 6 or divide by 10 is about the way it was described. Once you get all the digits counting and dividing right, the answer to your next question will be to use a BCD to seven segment decoder such as the 7446 or 7448. That will do the translation for the usual square number displays you're use to seeing on clocks. Then again, if this is mostly a learning exercise, we can do the same thing with a whole bunch of gates. Before going into that, or even the dividers, you need to get your input working consistently. You said it was sometimes clocking several times when you push the button on the clock input. This is quite common with mechanical switches. They tend to `bounce'. Usually too fast to see, the spring inside the switch will cause the contacts to strike several times before they settle down. Assuming you have the pull-up resistor on the CP input as recommended in an earlier reply, this is normal and will go away when you add the pulse circuit to get it running on its own. One minor nit in the recommendation to feed it with 5 volt AC. You will want to use a diode to get half-wave DC to the CP input. AC will swing negative on half the cycle and burn up your chip. To square it up a bit, I'd use another gate before the input. This assumes too that you're plugged into the wall to get AC in the first place. I'm guessing you're actually powering this from a battery or small DC power supply. Let's get it simply counting first, and worry about accuracy a bit later. I like the suggestion of using a 555 type clock chip. In it's simplest (monostable) mode, it can sit in between your button and the CP input, so it gives you ONE consistent pulse each time you hit the button. A resistor plus a capacitor set the length of the pulse. After that, hooking its output back to its own input will make it pulse repeatedly. The nice thing here is that depending on the size of the resistor and capacitor, it can be run at any speed from hours-per-pulse up to so-fast-you-can't-see-it. Have Fun, _Bill |
|
Nick Graber
开云体育ya that does so I do that for 10 and I do that for
6 and do that 3 times and I have a clock but first I am trying to hook a 7seg
led to a bcd to 7seg and cant find out how to do 1 2 3 ~ 10 11 12 and so on
although I can do them 11 22 33 44?after 9 I dont get numbers.
?
|
to navigate to use esc to dismiss