Setting the time

Discussion in 'The Projects Forum' started by Rocky_circuits, Nov 14, 2011.

  1. Rocky_circuits

    Thread Starter Member

    Nov 1, 2011
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    Hey guys. It's late and I'm in the lab pondering over how I can set the time. I'm using 74163 chips (I know, 4xxx family is easier) but I want these so I can use the nixie tube driver IC's.

    So my clock works fine, it counts the way it should *cough*
    I know how I can make it count fast to set the time... But that's not really how I want to do it. I want to make it count by "1" everytime I push a push button switch.

    The version of multisim I am using only has a toggle switch so I hope that isn't messin me up. Currently, I am playing with using some kind of logic gate with 2 inputs. 1 being my constant 1HZ oscilator and the other going to a switch with VCC.

    I think using a xnor gate works.. But I am just not quite sure since it is being wacko maybe in part due to it being a toggle switch and not a pushbutton
     
    Last edited: Nov 14, 2011
  2. SgtWookie

    Expert

    Jul 17, 2007
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    I don't see your circuit schematic.

    Hate to sound like a broken record here, but you should really know by now that we need schematics of what you're up to; it saves so much time and eliminates so many questions.

    Besides, without a series of schematics posted along the way, you really don't have a good record of where you started off and where you ended up.
     
  3. Rocky_circuits

    Thread Starter Member

    Nov 1, 2011
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    That's true, I apologize.
    Here's my schmematic. I think it works but the thing has this odd delay that I can't tell if it's just because of the program or that this doesn't really work. So the question at hand, will this simple set up work as a switch to advance time by 1?

    Edit: I have found that it works but it messes up my logic. Back to the drawing board I guess

    [​IMG]
     
    Last edited: Nov 14, 2011
  4. SgtWookie

    Expert

    Jul 17, 2007
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    I see that you have a SPST switch selecting between +5v and GND for one of the XNOR's inputs. Be aware that this might work OK in simulations, but in the real world you will have problems with "switch bounce"; also there is a period of time when the switch contacts are "in flight" and the switch common terminal will not be connected to anything. You want to be certain that any INPUTS always have a current path to +V or GND, or you can wind up with mysterious oscillations occurring that will be hard to track down.

    I don't recall seeing a schematic for your entire clock project. Are you using a 4060 to get an accurate time base? If so, you could use the SPST switch to select between your 1 second clock, and another clock output that is at a much higher frequency. Make certain to use a resistor from the common clk input to ground or V+ so that it doesn't "float".

    You may wish to have a "fast advance" and a "slow advance". Just having one speed to advance the time seems to either take forever to wait for the correct numbers to come up, or you overshoot and have to start over.
     
  5. Rocky_circuits

    Thread Starter Member

    Nov 1, 2011
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    0
    Yeah I am thinking that that will be my best option (using higher oscillations to set the time)
    I'm aware of the switch bouncing, but that's simple enough that I didn't include it in the simulation.
    If you remember my crystal oscillator thread, I actually got it working. I even ended up building a 2nd one.. Since it was half done already. The oscilloscope tells me 1Hz on each so I'm sure I could use somewhere between 2-8Hz for time setting. Or two like you said.
    Although I may preferrably have the faster oscillations on a pushbutton switch... Using a gate maybe.. Bah.

    Anyway, this is the schematic for my clock:
    http://img829.imageshack.us/img829/8467/circuitpicture.jpg
    (I don't got a thumbnail for this one)
    Edit: there's a mistake on the last counter chip with its CLK. That was fixed a while ago, it attaches to the output of the XNOR gate. And D goes to Qd. The program can be fidgety at times.

    I just realized that it counts from 12 to 00.. I'm going to cry. That's supposed to be 01.

    This project can be discouraging at times.
     
    Last edited: Nov 14, 2011
  6. SgtWookie

    Expert

    Jul 17, 2007
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    It's hard to make sense of the schematic, as you have wires running over the top of other wires, and it's very difficult to figure out what is what.
     
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