Current Level Detection

People do seem to get obsessed with magnetics as a detour to finishing.

I was just on a zoom meeting with the CEO of a big systems house. Big. We agreed that neither of us would ever elect to retire; we're having too much fun.

I never understood cruising or golf anyhow.

But you understand skiing. To each his own.

It's about the only thing that I can do all day and not think about stuff. And then I'm too tired and hungry to think about stuff.

Some things like water skiing or parachuting have a very low activity duty cycle. Well, hiking is pretty good.

Remarkably false. I'm not fond of magnetics, but sometimes they offer uniquely simple solutions, if not simple enough for John Larkin to understand easily.

Who hasn't? Admittedly my kilovolt inductor did have a gapped ferrite core, but it was saturated for most of the time the was a kilovolt or so around. Worked fine at starting a Xenon arc lamp (which needed about 20kV to get the initial spark discharge, and about a microsecond or so at hundred volts or so before the discharge went from glow - to arc.

It is certainly simple. But it's hard to isolate the sensing circuit from the circuit being sensed, which is often useful, and sometimes essential.

The original poster was Cursitor Doom. He's unlikely to be able to do it at all, no matter how simple the solution.

And a problem with tackling anything that isn't remarkably simple.

John Larkin has trouble understanding how magnetics work, and he imagines that everybody else has the same problem.

Not necessarily constructive fun.

They do seem to be about spending a lot of time talking to other people, most of whom aren't all that interested in electronics. One of my colleagues recommended the golf club as a place to drum up electronics business, but I wasn't willing to take hims seriously - I played field hockey back then, and golf was just hockey without the fun bits.

The example was a circa 500 kHz synchronous rectifier. Optos not optimal.

There are some great IC isolated gate drivers, delta-sigma ADCs, fast logic couplers, and analog signal couplers. Some have the highside power inverter built in.

PV optoisolators are cool too.

"Sounds moderately complex! "

"People do seem to get obsessed with" optos.

Some of us design electronics and do it the most sensible way.

Design something. Show us.

I guess you had better tell Chevy and BMW and Mercedes etc that they are all doing to wrong...

With these the negative battery lead passes through the sensor. Some provide a conditioned PWM output rather than analog.

To be fair there are also a number available that look like simple shunts.

A difficulty with the hall-effect ones is that the zero offset is difficult to control. An off-the-shelf car battery current sensor would probably not have the stability to discriminate 240mA from 200mA as in the original question.They are designed to tolerate hundreds of amps peak with single am resolution at low currents. A shunt resistor would have difficulty with that.

kw

Is that available in surface mount?

Yes. Hall effect sensors don't have a huge dynamic range and have bad TCs. But a shunt would be fine for the problem at hand. Shunts have low DC offsets!

But that wasn't the problem that Cursitor Doom asked us to address. Telling us that an off-the-shelf solution to a different problem won't solve his problem isn't a useful response.

In the problem posed by Cursitor Doom, the Hall effect sensor wouldn't need much dynamic range it just has to let him know when the current has dropped below 200mA. If it saturates a higher currents it wouldn't matter. It isn't going to burn out as a shunt resistor might.

But they do have a nasty habit of getting warm acting as thermocouple voltage sources.

Or at least in ways that the particular designer involved thinks is sensible. People with a pathological fear of magnetics wil go to great lengths to avoid them

Why bother. John Larkin doesn't pay any attention to other people's designs. He's here to harvest admiration for his own, and doesn't get as much of that as he'd like.

Cruising is completely rational. My idea of a vacation is to go someplace pretty and plunk down for a week or so, whereas Mo likes travelling round. A cruise is a reasonable compromise, at least part of the time. (We also travel for real and plunk for real, roughly alternately.)

We rented a place in Anna Maria FL for the month Feb 2020, which turned out to be excellent timing. ;)

Cheers

Phil Hobbs

To me a cruise ship would be like taking a holiday in a shopping mall.

My preference is by rail, stopping whenever I like and staying however long I feel.

Introduced early teens daughter to that in Kerala and Tamil Nadu. The consequence was that between school and university she took herself off to Australia for 6 months, and financed it herself.

Kind of synthetic for my taste. I prefer trails and waterfalls and picnics in the woods. There are ways to keep the beer cold.

I traveled to France once on the QE2, first class, and, well, there were too many people.

I know this is not what you asked for, but you might explain what you are wanting to accomplish. It sounds as if you have a car battery powering something which is not near a power outlet. And you want to know when the battery voltage drops to some level so you know the battery needs charging. If that is the case it might be easier to monitor the battery voltage instead of the current . Anyway what I am trying to say is sometimes it helps to step back and think about what you want to accomplish in the most basic terms.

Anyway it did not take too long to read this.

Dan