Reducing waveform amplitude

Discussion in 'The Projects Forum' started by Fluxor1964, Dec 6, 2018 at 9:15 AM.

  1. Fluxor1964

    Thread Starter Member

    Jun 11, 2015
    171
    5
    I just built a clock generator for testing logic using
    The NE555 timer, the output pulse is ok but is 9v, the same as the power supply rail, how can I use 9v power supply but have my square wave output at 5v pk to pk?
     
  2. ericgibbs

    Moderator

    Jan 29, 2010
    6,191
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    hi F,
    A resistor [390R or 430R] and say a 4.7V zener would be a simple option.
    E
    EDIT:
    A couple of series 2.3V Green diffused LED's in place of the zener would be a nice touch, see that it pulsing at lower rates
    AA1 06-Dec-18 14.47.gif
     
    Last edited: Dec 6, 2018 at 9:47 AM
  3. wayneh

    Expert

    Sep 9, 2010
    14,970
    5,439
    If you don’t need much current at 5V, you could even get away with a simple resistor voltage divider.
     
  4. crutschow

    Expert

    Mar 14, 2008
    20,225
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    What's the impedance of the load you want to drive with the 5V signal?
     
  5. Fluxor1964

    Thread Starter Member

    Jun 11, 2015
    171
    5

    I have no idea Crutschow... Will be feeding it into counter chips etc.
     
  6. ericgibbs

    Moderator

    Jan 29, 2010
    6,191
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    hi F,
    Which type of counters CMOS, TTL etc.??
    E
     
  7. crutschow

    Expert

    Mar 14, 2008
    20,225
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    Those are relatively high impedance loads, so Eric's circuit should work fine.
     
  8. ericgibbs

    Moderator

    Jan 29, 2010
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    hi C,
    I am a little concerned if the TS is using TTL, a 430R pull down may need a Schottky diodes across the 430R.
    E
     
  9. Fluxor1964

    Thread Starter Member

    Jun 11, 2015
    171
    5
    Yes I rather like the idea of a zener, i'll order some and try that.

    Thanks folks.
     
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