Pulse Witdth Meter

[Screech]

a few questions:

Do multimeters have this function?
I've noticed many multimeters have the Hz. funtion.
Do the ones with Hz function also do the duty function?

But Pulse Width?
I really nead a pulse width meter with a resolution of less then 1 millisecond.

I made a pulse width meter out of my computer, but it's not portable.
unless it's a laptop one. :?

Thanks

 

[Nigel Goodwin]

You could easily do it with a PIC and LCD display, even a BASIC STAMP would do - it has a pulse measuring command.

For a simple analogue meter, just average the pulses using a lowpass filter and feed a meter - it's basically a PWM signal, which is commonly used to provide a variable DC voltage from a micro-controller (a great many TV's use this method for the tuning voltage). The only difficulty is getting the low-pass filter right.

 

[discrete]

Nigel, I have heard about using a lowpass filter to convert digital PWM signals to analogue signals. What are the parameters to determine the cutoff-frequency of the lowpass filter though?

 

[Nigel Goodwin]

Nigel, I have heard about using a lowpass filter to convert digital PWM signals to analogue signals. What are the parameters to determine the cutoff-frequency of the lowpass filter though?

If you look on the MicroChip website at https://www.microchip.com they have an application note about using PWM to generate analogue voltages, they give the details there.

 

[Screech]

You could easily do it with a PIC and LCD display, .......

I wish it was easy, but I haven't got a clue. :?