DVA question.

[dakk1]

From what I'm reading on the Merc repair forum, I need a DVA to properly test some ignition components. <br />I understand that these components need to be tested at various RPM's.<br />I have a digital multimeter that will read up to 1000V Direct Voltage and will capture the Min/Max<br />values if need be.<br />What does a DVA do that this won't. Don't want to buy something I may not need.<br />Just trying to understand what a DVA does.<br />Thanks ... Dave.

 

[Perfidiajoe]

Re: DVA question.

DVA = Digital- Volt- Amp Meter

 

[CATransplant]

Re: DVA question.

As Perfidiajoe said, you already own a DVA if you have a digital multimeter. You're all set. Different terminology is all...same instrument.

 

[dakk1]

Re: DVA question.

Sorry for being ambiguous in my orignal post.<br />The DVA I'm referring to here, is known as a Direct Voltage Adapter. Don't want to be a dog chasing his tail, just wondered how it differs from what I have and if I need it... Dave

 

[Paul Moir]

Re: DVA question.

The DVA measures the peak amplitude of an AC signal. Say you have a signal where you get a 100v pulse for 1/100th of a second, once a second. Your digital meter set to AC volts will average this out to 1v (actually, it'll likely average it out to .7v or less, depending). A DVA will read the peak value, 100v.<br />Iboats sells a DVA adapter for your Digital Meter (search it for "DVA adapter"). Or you can get the Electronic Specialties model 640 for far less from their .com or maxrules dot com. (Sorry Iboats, but it's less than 1/2 the price).

 

[Indymike]

Re: DVA question.

Why can't one just do the math? Most multi-meters read RMS values. RMS X 1.414 = peak.

 

[Paul Moir]

Re: DVA question.

Because most multimeters don't read RMS values, they just average. And most 'True' RMS meters (which are expensive) have specific limitations like percent of duty cycle they can tolerate and frequency response. So you try to come up with a test that someone who's not skilled with electronics can understand and you're left with peak values.<br />If you know your meter and understand it's limitations, and can put an oscilloscope on the signal so you can make sure the wave you're reading is something your meter can comprehend then possibly you don't need a peak adapter. <br /><br />RMS x 1.414 is only true for pure sine waves. RMS x 2 is true for 50% duty cycle square waves for example.

 

[dakk1]

Re: DVA question.

Thanks, Paul for the explaination. Just what I wanted to know.. Dave

 

[Indymike]

Re: DVA question.

Thanks Paul. Makes sense. My meter does read true rms, but I had the thought about the pure sine being a limiting factor.