Ok. Give me an example of working on something in which a clamp meter with true RMS would have been the better meter to use. Does it only amount to more accurate volt/current reading on circuits that aren't perfect sine waves?

 

SSCULLY might give you a better answer than me. "RMS" is the "average" voltage/current value in an ac circuit, but notice I put the word average in quotes, because a true average would be zero, since the positive amplitude of the waveform is matched by the negative value. A way around this problem is to square the values, then take their square root (a Root Mean Squared value). It's a bit similar to the way standard deviation in statistics is calculated.

So I didn't really answer your question. But I don't know that you can actually buy a clamp meter (or ac meter) that doesn't give you the RMS reading.

- Jack

 

True RMS works better than the normal meters in inverters or where armonics are present, AC motor drives, etc.

 

^ Like variable speed motor drives?

 

Basically....A "regular" (non-true-RMS) meter uses a circuit that gives an accurate RMS reading only if you're measuring a sine wave. If you're measuring some other variety of AC (e.g. a modified square wave as produced by many types of 12V to 120V power inverters), these "regular" meters will not read accurately. A "true RMS" meter has a different, more-complex and expensive circuit, that can give accurate RMS reads for more than just sine wave AC.

 

That answer makes perfect sense. A square wave has a lower amplitude than a sine wave for an equal RMS voltage.

- Jack

 

Now isn't science fun!?

thanks guys

 

Great Info! Man there's allot to learn here, -it is fun. I have a question. I need a esr meter, - thinking about giving this one a try -

http://www.ebay.com/itm/Capanalyzer-...item5d30156297

Is it worth the cash over the cheaper versions ?

Like say this -

http://www.ebay.com/itm/220777497132...84.m1423.l2649

 

^ I have no idea. haha

 

That helps lol. My luck I'll need the expensive one. Definitely want a dedicated ESR meter.

I have a couple fairly good Fluke meters, but nothing with capacitance. Currently working on a Dell Power Supply, -not the norm, - this supply has 11 transformers, = head ache.

But yea, my clamp meter is true RMS, -other is average responding, RMS calibrated.

 

A Dell power supply is not worth fixing - toss it and get a quality replacement.

 

They don't make them anymore. It's a Dell Plasma supply, 400 Volt.

 

^ From a TV?

 

Yea, a Dell Plasma TV 42". Either I fix it or it's going to the curb lol. I took some pics of the supply before removing it -



It's built fairly well, but the problem with Dells was heat. No fans to circulate air, so... My brother gave it to me to fix, it was given to him at work. I told him forget it, -he doesn't want it back. So now I have it hanging from the rafters in the basement lol.

I guess they were pretty expensive at one time, - nice picture when they worked. The power board itself is made by Samsung. Internally it's Samsung/Phillips.

BTW, -It's 190-200 volt continuous . The large caps are 400 volt. Yea, they can kill yuh

 

I've got an old space invaders game I'm working on when I' in the mood (lazy).
It has a huge transformer in it, with many voltage legs coming off of it. I think I've isolated the problem to one of the voltage legs. I'm trying to figure out the amperage transformer I need to replace that leg with. I'm not expert on electronics, (plus this stuff is antique), do you have any suggestions?