TTL low to high square waveform or Positive & negative cycle square waveform's?

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danny davis

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TTL low to high square waveform or Positive & negative cycle square waveform's?

TTL low to high square waveform or Positive & negative cycle square waveform's?

How do you know if you have a low ( zero volts ) to HIGH ( +5 volts ) square waveform OR a positive and negative cycle square waveform?

Because a TTL signal goes from zero volts to + 5 volts , so you can say it has a 2.5 volt DC offset?

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I measure the DC offsets with my DC volt meter because the oscilloscope confuses me about DC offsets on where they start

Once I get the DC offset voltage, i use the oscilloscope to measure the square waveform

The Problem I'm confused about is , is the square waveform starting at the baseline of the square waveform or is it starting at the halfway between the top and bottom?

So I'm not sure is the square waveform is riding on top of the DC offset voltage from the baseline or from the halfway point

TTL square waveforms start from the baseline right? CMOS square waveforms start at the half way point of a square waveform right?
 

Re: TTL low to high square waveform or Positive & negative cycle square waveform's?

The power supply is +12 and -12

The square waveform's range from 5 volts peak , 10 volts peak , 12 volts peak

Some of the square waveform's have DC offset

I measure the DC offset with my DVM meter, it will have 1.5 volts or 2 volts DC offset voltage

Is the square waveform starting at the base line at 1.5 volts DC offset or is the square waveform starting at half way 50% amplitude at 1.5 volts DC offset?

Zero can be either
1.) Starting at the baseline, logic zero volts , which is called "Monopolar" because its just low and high states
2.) Starting at 50% amplitude of a square waveform , which is called "bipolar" because it has a positive and negative cycles

When do you or a tech knows when a square waveform "starts" at 50% amplitude and not at zero volts 0% baseline?

How do you know when the square waveform has positive and negative cycles that its alternating?

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1. Uni-directional Waveforms - these waveforms are always positive or negative in nature flowing in one forward direction only as they do not cross the zero axis point. Common uni-directional waveforms include Square-wave timing signals, Clock pulses and Trigger pulses.

2. Bi-directional Waveforms - these waveforms are also called alternating waveforms as they alternate from a positive direction to a negative direction constantly crossing the zero axis point.

How does a tech know if the square waveform is a bi-directional square waveform?

The power supply is +12 and -12 volts
 

Re: TTL low to high square waveform or Positive & negative cycle square waveform's?


All these things are easily observable on the oscilloscope - just use DC option!
Any square wave that is not symmetrical with respect to 0V has a DC-offset (average value).
Where does it start? Periodic waves have no begining or end, it's up to you and your convenience to define where you want to be .....
:wink:
IanP
 
Last edited:

Re: TTL low to high square waveform or Positive & negative cycle square waveform's?

Where does it start? Periodic waves have no begining or end, it's up to you and your convenience to define where you want to be
Click to expand...

How does a tech know if the square waveform is a bi-directional square waveform?

How does a tech know if the square waveform is uni-directional or Bi-Directional, has a positive or negative cycle?

The power supply is +12 and -12 volts
 

Re: TTL low to high square waveform or Positive & negative cycle square waveform's?

danny davis said:
How does a tech know if the square waveform is a bi-directional square waveform?

How does a tech know if the square waveform is uni-directional or Bi-Directional, has a positive or negative cycle?
Click to expand...
He/she uses an oscilloscope set to DC.
 

Re: TTL low to high square waveform or Positive & negative cycle square waveform's?

He/she uses an oscilloscope set to DC.
Click to expand...

I do

But how do you know if the logic stages are uni-directional or bipolar , bi directional?

Square waveforms can be either way

- - - Updated - - -

He/she uses an oscilloscope set to DC.
Click to expand...

I do

But how do you know if the logic stages are uni-directional or bipolar , bi directional?

Square waveforms can be either way
 

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