How to generate a clock pulse?

Discussion in 'General Electronics Chat' started by alexlesuper, May 9, 2011.

  1. alexlesuper

    Thread Starter New Member

    May 9, 2011
    Hello forum,

    I am new to electronics and for my first project I have decided to build an ADC. I am using the design found on this very site:

    To complete this, I need to use a clock pulse to drive the counter. However, I am not sure how to generate such a clock pulse. For now I am simply using an arduino and hard coded a digital signal that goes up and down. However, when I am going to solder everything in, I will need something else to generate the clock pulse. I looked around on digikey and googled a bit, but I am a bit confused as to what I really need. Do I need a crystal oscillator? What is ideal in my situation?

    Thanks in advance for the help. :)
  2. beenthere

    Retired Moderator

    Apr 20, 2004
  3. nbw


    May 8, 2011
    A simple 555 astable?That may or may not be accurate enough. There are a bunch of options out there :)
  4. magnet18

    Senior Member

    Dec 22, 2010
    This is extremely accurate.
  5. Jaguarjoe

    Active Member

    Apr 7, 2010
    I don't think he wants a 1Hz clock. The U/D counter in his ADC circuit would then be so slow it would never be able to keep up with even a slow moving input signal.
    I also don't believe clock stability matters either (within reason anyhow). All its affecting is slight changes in compare time which is insignificant for what he's doing.
    A 555 is cheap, pretty stable and also very adjustable which would allow him to see exactly how clock speed affects a counting ADC.
  6. magnet18

    Senior Member

    Dec 22, 2010
    If the OP does go with the 4060 then there are multiple signal outputs at various frequencies, and it can be changed by changing the capacitor values.
    But if accuracy is irrelevant a 555 is probably the way to go.
  7. nbw


    May 8, 2011
    You could give it a try with a 555 to test the rest of the circuit; as mentioned thougha 4060 circuit with a crystal (rather than oscillator) tapped off at an appropriate output would give you a very accurate timebase.
  8. radiohead

    Distinguished Member

    May 28, 2009
    the Unijunction transistor excellent for generating pulses when used in a relaxation oscillator.
  9. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    The OP has left the building.