Starting voltage for Duty cycle measurments.

[Kiriakos-GR]

Well I am a bit confused about duty cycle.

There is some multimeters with different minimum input level in volts Peak to Peak so to measure properly duty cycle.
And I have to ask what is the minimum requirements in input voltage that some one will use in electronics.

I simple words if a multimeter needs a minimum of 5 volts so to measure properly duty cycle, its useful for measuring the duty cycle in PWM  fan at 5V, plus any fan with higher voltage.

But is this specification good enough for a wider use ?

 

   

 

[Armin_Balija]

I would say it depends on the voltage threshold your circuit needs to see a HIGH signal in logic circuits?

[Simon]

I'm assuming the voltage given is indeed the minimum required by the meter to distinguish between high and low, a bit like I/O voltages on digital chip families

[y33t]

Well I am a bit confused about duty cycle.

There is some multimeters with different minimum input level in volts Peak to Peak so to measure properly duty cycle.
And I have to ask what is the minimum requirements in input voltage that some one will use in electronics.

I simple words if a multimeter needs a minimum of 5 volts so to measure properly duty cycle, its useful for measuring the duty cycle in PWM  fan at 5V, plus any fan with higher voltage.

But is this specification good enough for a wider use ?

 

   

I had performed frequency counting of a PWM signal having a 120nV amplitude.  It all depends on you application and purpose, AFAIK there is no standard for this.

[Kiriakos-GR]

The point is that would any one describe this multimeter as insensitive ?
%Duty Cycle 0.1% -- 99.99%
Input Frequency: 5Hz -- 500 kHz, 5V Logic Family

What this stands for ?

[Kiriakos-GR]

I think that I found some theory about that.

It is about signal testing on PSU,  the general specification is : Logic  level high = Between  2.4 V and  5 V ( square wave) output while sourcing 200uA
AC / DC  Universal  Input Switch Mode  Power  Supply

The mystery is that I have three multimeters, the one reads 51% duty cycle the second 45% and the third 37%.
And I do not know what to believe, voltage input 2.4V ( square wave) 1KHz .

[slateraptor]

The mystery is that I have three multimeters, the one reads 51% duty cycle the second 45% and the third 37%.
And I do not know what to believe, voltage input 2.4V ( square wave) 1KHz .

I'd wager to say none are believable; it looks like you're attempting to measure very close to trigger threshold.

If you can increase the amplitude of your square wave (and assuming your meters are reliable), I suspect your meter measurements will converge.

[Kiriakos-GR]

I will get in few hours one professional signal generator with 0-20V PP and I will retest.

[slateraptor]

I will get in few hours one professional signal generator with 0-20V PP and I will retest.

Sweet. Let us know how it turns out.

[Short Circuit]

"5V Logic" means nothing, it all depends on the signalling levels. 5V TTL is very different from 5V CMOS.