Uses for the Square wave fixed frequency output on DMMs? - Page 1
Forum section: electronics / testgear

author: kalel
author_rank: Frequent Contributor
timestamp: July 02, 2017, 10:59:54 am
content: I asked previously about some uses of the manual hold button.This time, I would like to ask about the fixed frequency output "square wave" function of multimeters. Usually it's a fixed 50 Hz with 0.5 duty cycle. At least a few meters offer it, starting from the famous DT series.What could this function be used for? In case it's only available on cheap multimeters, I would assume it's not designed especially as a kind of test signal for a scope, plus it likely wouldn't make a good/accurate one anyway.I'm not sure if there's enough power to test with any LEDs or beepers. Maybe for testing simple transistor amplification circuits? If you only have a transistor, an LED and no other source for the gate signal, perhaps it makes sense. Maybe there's no specific intention, but I imagine this could have more uses than the manual hold button.

author: alm
author_rank: Super Contributor
timestamp: July 02, 2017, 11:20:57 am
content: Given that it is only found on cheap meters, unlike the hold button, I am not so sure about the more useful part. I can only see it being useful if you have some other meter or scope to observe the output of your circuit.

author: WhichEnt2
author_rank: Regular Contributor
timestamp: July 02, 2017, 11:28:44 am
content: I heard once that it function being used for checking the segments on the liquid crystal displays or something.

author: bjcuizon
author_rank: Frequent Contributor
timestamp: July 03, 2017, 07:16:31 am
content: Maybe it is for testing some kind of audio device.I tried using it to test some audio amp and it outputs something like the 50Hz mains hum (like when you plug in a guitar cable for example.)

author: BU508A
author_rank: Super Contributor
timestamp: July 03, 2017, 08:27:32 am
content: Quote from: alm on July 02, 2017, 11:20:57 amI would not consider the Agilent U1252B as a "cheap meter".

author: Electro Detective
author_rank: Super Contributor
timestamp: July 03, 2017, 08:40:58 am
content: Whatever priced meter it's on, it would be handy as a go / no-go speaker tester, or certain mf types of capacitors ?

author: jpb
author_rank: Super Contributor
timestamp: July 03, 2017, 09:09:06 am
content: Quote from: BU508A on July 03, 2017, 08:27:32 amIt is not, but it does not have a fixed frequency, fixed duty cycle square wave output. Its square wave output is variable in frequency and duty cycle so could be used with pwm circuits.Some cheap meters, apparently, have just one fixed frequency 50% duty cycle output which is rather less useful and I suspect is more a marketing thing so it looks like they have the same as more expensive meters.

author: Fungus
author_rank: Super Contributor
timestamp: July 03, 2017, 10:23:25 am
content: Quote from: jpb on July 03, 2017, 09:09:06 amI suspect the OP is talking about the new AN8008, which isn't fixed frequency.

author: kalel
author_rank: Frequent Contributor
timestamp: July 03, 2017, 11:22:39 am
content: Quote from: Fungus on July 03, 2017, 10:23:25 amActually I was talking about the fixed frequency ones (I have a DT with that function, never found much use for it), but as for AN8008, it's a shame it doesn't offer a temperature setting like AN8002.

author: Fungus
author_rank: Super Contributor
timestamp: July 03, 2017, 11:29:10 am
content: Quote from: kalel on July 03, 2017, 11:22:39 amI think it can be hacked to enable it, but at that price you can have both!

author: Shock
author_rank: Super Contributor
timestamp: July 04, 2017, 04:51:55 am
content: Keysight U1252B User’s and Service Guide: Square Wave OutputQuoteOn this specific meter you can adjust the frequency, duty cycle and pulse width.

author: Crumble
author_rank: Regular Contributor
timestamp: July 17, 2017, 09:22:40 pm
content: Quote from: Fungus on July 03, 2017, 11:29:10 amI have an AN8002, but I usually use a generic TM-902C temperature meter for measuring temperature. They are just a few $, and they liberate a multimeter for the electric work. I'd recommend to get one of those.