Products > Test Equipment

AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter

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Mark Hennessy:

--- Quote from: Andrey_irk on July 15, 2017, 01:45:19 pm ---Square wave generator is useful for checking different speakers and buzzers. I'm surprised nobody pointed it out.

--- End quote ---

Sadly not as useful as you might think...

As I mentioned earlier, the square wave comes from quite a high source impedance (about 2k). So by the time you've fed that into an 8 ohm loudspeaker, there's hardly any voltage there. I tried a very sensitive 15 ohm speaker, and you have to hold it to your ear to hear anything from it.

However, it does work on piezo sounders :-+

deflicted:

--- Quote from: Mark Hennessy on July 15, 2017, 06:41:09 pm ---
--- Quote from: Andrey_irk on July 15, 2017, 01:45:19 pm ---Square wave generator is useful for checking different speakers and buzzers. I'm surprised nobody pointed it out.

--- End quote ---

Sadly not as useful as you might think...

As I mentioned earlier, the square wave comes from quite a high source impedance (about 2k). So by the time you've fed that into an 8 ohm loudspeaker, there's hardly any voltage there. I tried a very sensitive 15 ohm speaker, and you have to hold it to your ear to hear anything from it.

However, it does work on piezo sounders :-+

--- End quote ---

Noob question: I seem to recall reading somewhere that square waves are bad for speakers because the flat parts look like DC, and DC ruins speakers. And supposedly that's why clipping is bad as well, because it starts to look like a square wave, which is too much like DC. Not being an electronics guy, I just thought, hmm, well sounds plausible. Granted, I'm guessing it probably doesn't matter much for tiny piezo speakers and such. Also, I'm guessing this little multimeter square wave doesn't have nearly enough power to ruin a speaker, regardless.

But is there some truth to this, or is this just one of those audiophile myths that get thrown around?

tronde:

--- Quote from: Andrey_irk on July 15, 2017, 01:45:19 pm ---

P.S. It's funny to see people here discussing a thread on kazus.ru. But yeah, their discussion seems to be the most comprehensive one on that matter. I can try to translate something for you if google fails.

--- End quote ---
That is great offer, really! What would be nice for us non-russian speaking people is if you could give a hint when something interesting is discussed there. Google translate is usually OK if you know what you are translating, but quite often interesting things are "hidden" in a lot of text so it goes under the radar. One thing is that the language is different, but when the alphabet is different too, it becomes difficult to spot such things.

b_force:
It's just to bad for the current, which blows my mind because the voltage ranges are fine.

I was just wondering, wouldn't be an idea to develop a small daughter board to provide the correct input protection and maybe some extra extra tweaks to get a better current range?

ocw:

--- Quote ---It's just too bad for the current...
--- End quote ---

Place a 1 ohm resistor across a Pomona 1330-2 (or similar), plug that into the AN8008 ground and voltage inputs, connect the current measurement wires to the top of the 1330-2 and the mV reading = mA.

It would be nice if that wasn't required, however.

Adding a battery test function could be done the same way.

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