DC Ammeter 500mA

[dpb]

I posted a month or so ago about fixing up butchered wiring on choke circuit for old JLG 40H manlift -- got it going and on to next step...

Have had to replace a couple of the function controllers (swing/lift) which have builtin ramp circuitry to avoid "bang-bang" operation.

Unfortunately, the new ones are never tuned to the machine and to do so require measuring current and adjusting the hi/lo/ramp pots per a set of ranging operation of the controller.

The current range is from 500mA to ~1A DC; my Fluke and other multimeters are limited to 300/400 mA on the ranging scale or 10A full scale. Unfortunately, the 10A range doesn't scale so is only 1 digit precision which isn't sufficient to adjust...

So, question is, does anybody know of reasonably-priced DMM that has such a current range?

I have a Tek multifunction scope DMM plugin module that is good range but it's corded and bulky and not terribly convenient to put in the lift bucket because final adjustments require moving the controls while operating so the corded operation is a real hassle...

[micky]

Post to sci.electronics.repair

[dpb]

...

Well, I remembered having a resistor collection so found a 100 ohm that measured right at 100.0 and made a shunt lead...worked like a champ.

Discovered the 'ON' current was _way_ too hot on the new controllers as they come shipped; the ramp function has no chance against it. Backed 'em off to factory spec of 300 mA Lo and 550-600 mA Hi and then, instead of a bucking bronco, one has a pleasant ride! :)

I'm _much_ happier now... :)

[Ralph Mowery]

Glad you got the current measured.

My fluke meter tops out at less than 1 amp on the ma scale, but on the

10 amp scale it will show down to 1 ma of resolution.

[dpb]

My Fluke is just the HVAC handyman clamp meter I picked up off eBay for $15 which is great for what it is but only has AC current.

My other DVM is an old Micronta which for some reason only ends up showing 2 digits on the 10A scale...

I did take the 'scope out and used it initially to double-check "calibration" on the shunt voltage measurement to make sure but then could just use it for the settings so didn't have to try to keep the power cord while operating...

[Peter]

My el-cheapo Extech MN35, available for $20 on-line, can measure 10A DC with a specification of +/- 3.0% reading to 5 digits. Don't know if it would meet your needs, but I've had this item for several years and used it for general household and simple electronic troubleshooting tasks. For my purposes, it's entirely satisfactory.

[dpb]

On 9/30/2018 8:30 AM, Peter wrote: ...

Thanks...I'm learning that apparently now even the less expensive DVMs will autorange on the 10A input; apparently it's that my old Micronta is so old (30 at least) that wasn't so then...it just shows fixed 1 decimal point -- you're supposed to be measuring >1A I guess; not the range between the 300 mA fused and 1 A where the lift controllers operate.

It worked very well for calibrating the coal analyzers proportional controls circuitry that were 4-20 current loop which was its prime function back then... :)