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Gratuitous Continuity Speed Test and Comparisons
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joeqsmith:
I measure the resistance required for the meter to measure an open and a short.  I measure the short circuit current and open circuit voltage.   For the speed test, I use a 50% duty cycle and increase the frequency until the meter no longer detects a short.  I then use a fixed 2Hz and reduce the on time until the meter can't detect it.   All of that data is recorded and available on-line.

To apply a short for the frequency test, I have a driver that controls three FETs, allowing me to run up to three meters.  The reason for this is some have asked about the meters response time.  With this, I can use a 1000fps camera to watch their LCDs.   

I try to measure when I actually hear a full beep.  Some meters that do not have a latching input can respond so fast, you may hear something but it may not be a beep.   For example, shown is the UNI-T UT90A.  This meter is non-latching and has a very fast response.   This allowed me to modulate a one-shot that has an on-time short enough not to cause the meter to beep but long enough to make it click.   What you are hearing is a series of clicks.   Sorry but I did not take any photos of that circuit (built on a breadboard) nor did I document it.  It was more just for fun rather than used as a metric for evaluating meters.   

***
Just some additional info.

Corrected error above, only 3 meters can be checked at a time.  The 9V and forth FET provide the level shift and drive.   
The resistance is measured using a resistor substitution box.  Mine has a 1 ohm resolution and finding the sweet spot is fairly quick. 
The current and voltage are checked with an HP34401A. 
Normally I am using my Tektronix AWG2401 arb to derive the pulse.   This runs from LabView.
FETs are some very old Siemens BUZ 72 N-channel,   most likely from the 80s.  Not critical and what was in my junk drawer.  Because the meters are all isolated, they self bias.  So no big deal driving them this way. 

Datasheet
https://docs.rs-online.com/e916/0900766b80026b66.pdf

***
A bit off topic.  Dave testing the setting time of a few meters.   This is why I support running more than one meter with my setup.     
https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg2786500/#msg2786500

***
Repeat from the last time it came up:
https://www.eevblog.com/forum/testgear/multimeter-with-continuity-test-buzzer-that-responds-immediately/msg3168420/#msg3168420


KungFuJosh:
Joe, thanks for your reply and info. It seems to me that what you've done to measure the resistance required to set off the continuity is an important factor.

Would you mind drawing a diagram of your test setup? I'd like to setup something standard for more consistent testing.

I'm also curious about how flexible thresholds effect continuity speeds. I don't remember, do you have any Siglent bench DMMs? Or another brand where that can be manually set?

On my Siglent bench DMMs, it seems to me to be significantly faster with a higher threshold set. For example, when the threshold was set to 50Ω, it appeared to be much slower compared to setting the threshold to 500Ω or 1kΩ.

Thanks,
Josh
Fungus:

--- Quote from: KungFuJosh on August 13, 2024, 12:08:59 am ---Joe, thanks for your reply and info. It seems to me that what you've done to measure the resistance required to set off the continuity is an important factor.

Would you mind drawing a diagram of your test setup?

--- End quote ---

A potentiometer...?
KungFuJosh:

--- Quote from: Fungus on August 13, 2024, 12:13:05 am ---A potentiometer...?

--- End quote ---

 :-DD :-DD :-DD

I meant the whole speed test rig, not how he determined the needed resistance. 🤣
joeqsmith:

--- Quote from: KungFuJosh on August 13, 2024, 12:08:59 am ---Would you mind drawing a diagram of your test setup? I'd like to setup something standard for more consistent testing.
--- End quote ---
See attached.   I suggest using no more than a 5 ohm output resistance just based on the meters I have looked at.   The other values are not critical.


--- Quote from: KungFuJosh on August 13, 2024, 12:08:59 am ---I'm also curious about how flexible thresholds effect continuity speeds. I don't remember, do you have any Siglent bench DMMs? Or another brand where that can be manually set?
--- End quote ---
I don't own any Siglent products.  The Gossen Ultra or Prime as they renamed it, supports this. 
 

--- Quote from: KungFuJosh on August 13, 2024, 12:08:59 am ---On my Siglent bench DMMs, it seems to me to be significantly faster with a higher threshold set. For example, when the threshold was set to 50Ω, it appeared to be much slower compared to setting the threshold to 500Ω or 1kΩ.

--- End quote ---
Personally, I just want it fast enough to detect when sliding the leads over a large QFP.  Anymore though, that is less of a concern as we mostly work with BGAs and I no longer do much reverse engineering.
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