Author Topic: Current Probe for GW121?  (Read 1277 times)

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Offline mtgstuberTopic starter

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Current Probe for GW121?
« on: September 10, 2023, 07:23:16 am »
Hi folks,
    I just picked up a GW121, primarily for the logging capabilities.  I considered the Keysight 12xx series, but there didn't seem to be a way to do interval logging without connecting a phone or computer.  I considered the Fluke 287/289, but didn't really want to spend that much, given that I have a series of other meters.  I liked the open nature of the GW121.
    I'm interested in picking up a current clamp / current probe for the GW121.  I don't really need high currents.  I have two other clamp meters, but they don't do data logging. 
    Any thoughts on a clamp probe that I could use with the GW121?   I'm primarily interested in being able to log currents in household and automobile applications.  30 or 40 A is fine for an upper limit -- in fact it's preferred, as I'm interested in more low end detection capability.
 

Online Kleinstein

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Re: Current Probe for GW121?
« Reply #1 on: September 10, 2023, 07:28:36 am »
For AC there are relatively cheap external current clamps that give out a proportional voltage. One can also use some kind of DIY or commercial current transformer.

For DC things are more complicated as a DC current clamp needs an active circuit and can be tricky with small currents as an external magentic field can effect the readings.
 

Offline BILLPOD

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Re: Current Probe for GW121?
« Reply #2 on: September 10, 2023, 01:12:25 pm »
The clamp accessory that pairs with the new Uni-T UT117c DMM also works with my 121GW, on the mV range.   Good to 400A AC, (no DC).
It is model # UT-CS06A and is only around $20 USD. :popcorn:
 

Offline mendip_discovery

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Re: Current Probe for GW121?
« Reply #3 on: September 10, 2023, 02:28:18 pm »
I have yet to find a sensible clamp meter. I might get some shunts but they are a bit of a pain when working in a vehicle and all you want to do is log the current as you change the rpm.

I would say I am looking at <200A.

I did buy an amazon cheap thing but I have yet to get repeatable numbers with it.
Motorcyclist, Nerd, and I work in a Calibration Lab :-)
--
So everyone is clear, Calibration = Taking Measurement against a known source, Verification = Checking Calibration against Specification, Adjustment = Adjusting the unit to be within specifications.
 

Offline bicycleguy

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Re: Current Probe for GW121?
« Reply #4 on: September 12, 2023, 12:13:34 am »
A Micsig CP2100A works great using a bnc to plug adapter and is even better with an oscilloscope for when you need to see what's really going on.
 

Offline J-R

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Re: Current Probe for GW121?
« Reply #5 on: September 12, 2023, 07:21:02 am »
Most scope probes like the Micsig use USB for power and also have relatively long leads.  This is fine for bench use but a bit obnoxious otherwise in my opinion, compared to a battery-powered unit.  But maybe your use case demands constant power...

I found some reasonably priced DMM current clamp options on ebay:

Lutron CA-501 - https://www.ebay.com/itm/175332271175
Fluke i410 - https://www.ebay.com/itm/235194669723
CA-60 - https://www.ebay.com/itm/314783580198  https://www.ebay.com/itm/364389082567
Mac Tools EM121 - https://www.ebay.com/itm/186066308842

I have both the CA-60 and the Micsig CP2100B.  Accuracy is a bit tricky.  DC clamps like to be zeroed constantly...  A shunt resistor is the better option if at all possible.
 

Offline Jeroen3

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Re: Current Probe for GW121?
« Reply #6 on: September 12, 2023, 10:00:47 am »
There is the occasional fluke i30s for sale on ebay for a lot of money.
 

Offline Njk

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Re: Current Probe for GW121?
« Reply #7 on: September 12, 2023, 11:26:02 am »
What about Hantek CC-65? It's extensively reviewed here, with all the schematics and comprehensive modding instructions. Still in production.

https://www.eevblog.com/forum/testgear/hantek-cc-65-acdc-current-probe-teardown-and-testing/
 


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