Re: TIP: Current Probes ...

stefan_trethan
 

If you only need low frequency the LEM brand hall effect sensors, I
believe Allegro also makes chip based ones, can be an option.
Also remember you can put 10 turns through if you need more
sensitivity (insertion impedance permitting).

ST

On Sun, Dec 9, 2018 at 6:30 PM David Slipper <softfoot@...> wrote:


I quite often have a need to sense small currents (~10-200mA) and have
always wanted a clamp on current probe but even the used ones for a
scope are out of my budget.

A series resister is one solution but it is rather intrusive and
sometimes the circuit cannot tolerate the voltage drop.

Recently, at a garage sale I came across an old RS current clamp
intended to be used with a multimeter, it is a Hall effect device so
it's good for DC too, so just as an experiment I attached it to my scope
with a "banana<--->BNC" adapter and it works a treat :-)

The sensitivity is 1mV for 10mA and the bandwidth seems adequate for my
needs. If I need better sensitivity I just wind the wire 10 times around
the sensor clamp which gets me 1mV per 1mA.

Since I'm trying to get an Arduino and ESP8266 WiFi adapter to run on
batteries it is proving invaluable.

It may not have the bandwidth of a purpose built 'scope current probe
but it seems OK for my needs.

Dave




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