Wireless amp gauge

rrlund

Well-known Member
Years ago, Dad was a school bus mechanic. He had a little wireless amp gauge that you could just hold close to the posts on a generator and it would read amperage. Anybody ever seen one or know what I'm talking about? It was about the size of a little travel alarm clock. It had a chrome back and a brown face that just has a simple amp gauge in it.I searched Google and can't find anything even similar. I haven't been in his garage in years, can't even get to the work bench for all the junk to see if he had it or not. Might have belonged to the school and he didn't get it when he brought his tools home.
 
Randy, I think I have something like that. It also reads starter amp load by holding it against the cable as you run the starter. I don't know how accurate it is. I can't remember the brand name, but I'll look when I get back out from lunch.
 
(quoted from post at 09:38:18 06/09/22) Years ago, Dad was a school bus mechanic. He had a little wireless amp gauge that you could just hold close to the posts on a generator and it would read amperage. Anybody ever seen one or know what I'm talking about? It was about the size of a little travel alarm clock. It had a chrome back and a brown face that just has a simple amp gauge in it.I searched Google and can't find anything even similar. I haven't been in his garage in years, can't even get to the work bench for all the junk to see if he had it or not. Might have belonged to the school and he didn't get it when he brought his tools home.

GOOGLE "hand-held inductive ammeter".

Depending on how many Amps you need to measure they now make ''clamp on Ammeters'' much like the old Amprobes that could only read AC Amps that are capable of reading DC Amps, as well.

GOOGLE "clamp-on DC Ammeter".
 
I have several my Snap-on brand has two wire guides on the back, and 2 scales one for Cranking amps and one for charging amps. Others have only one or the other, not both. Accuracy as in small percentage is not needed. Jim
 
Like mine....large slot for battery cable & small slot for wire.
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I guess that's pretty close. Closer than the digital things that I found searching DC ammeter. Do you actually have to touch those
things on the back to a post? This one didn't. It didn't have a battery or anything. As far as I know it was just magnetic or
something. Many's the time I've wondered if a generator was working and wished I had that thing. Just hold it half an inch or so
from the post and it would read positive, negative or zero. Nothing could ever be any simpler.
 
(quoted from post at 11:56:43 06/09/22) I guess that's pretty close. Closer than the digital things that I found searching DC ammeter. Do you actually have to touch those
things on the back to a post? This one didn't. It didn't have a battery or anything. As far as I know it was just magnetic or
something. Many's the time I've wondered if a generator was working and wished I had that thing. Just hold it half an inch or so
from the post and it would read positive, negative or zero. Nothing could ever be any simpler.

Referring to the old-style ones, there's a sort of ''guide'' or ''slot'' on the back and you straddle the charging wire with it, anywhere along the length of the wire, has NOTHING to do with being near a terminal post.

The memory must be a little ''off'' on that detail. :wink:
 
I have had one for many years. Not real accurate but gets you in the ball park. Have up graded last twenty years or so to a clamp over wire multimeter that works very good.
My old 37 Ford ammeter did not have a wire connection on it . The wire was just securely clamped to back of meter.

Actually all those low voltage ammeters with terminals for wires are just hooked to a shunt inside so no current actually runs through any windings except the shunt. Not like fuel gauges etc that have balancing coils ( I call them ) to pull needle one way or the other.
 
I have one about two inches square with two scales. It has two bars on the back with large and small notches. Large is for starter current, small for generator. I can't vouch for accuracy but it gives you an idea of what's going on. KD Tools as I recall.
 
I have one hanging in the shop they come in handy at times. The flow of current creates a magnetic field and the more the current the greater the field.

John T
 
Hans Christian rsted discovered that electric currents create magnetic fields, which was the first connection found between electricity and magnetism. He is still known today for Oersteds Law and the oersted (Oe), the cgs unit of magnetic H-field strength, is named after him.

I think Orstead used a compass to determine the connection between electricity and magnetism. The most dreaded class in college was E&M.
 
I didn't mind E & M, it was a course titled Electronics of Solids that included Quantum Mechanics and Maxwells Equations that drove me to drink lol Good Old Purdue in the late sixties, what a time

John T
 
I have one that belonged to my dad. It's about fifty years old. I suppose it's useful, but these days I always rely on a voltmeter when working on charging system problems.
 
(quoted from post at 14:56:43 06/09/22) I guess that's pretty close. Closer than the digital things that I found searching DC ammeter. Do you actually have to touch those
things on the back to a post? This one didn't. It didn't have a battery or anything. As far as I know it was just magnetic or
something. Many's the time I've wondered if a generator was working and wished I had that thing. Just hold it half an inch or so
from the post and it would read positive, negative or zero. Nothing could ever be any simpler.
o electrical contact, just like old Ford tractors.

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I don't think we needed an excuse to drink back in the 60's.
But if you want to blame Quantum Mechanics and Maxwells Equations, that's OK.

I have two kids. After the last one, I stopped drinking.
 
Ahh Maxwell's equations, propagation of electromagnetic fields in waveguides. Good times. Right hand rule applies.
 
You may be mistaken about just holding it near the alternator/generator. The ones I have saw had two post. One measured volts, the other amps. Or maybe either amps or volts. Dad had one two post that measured amps. Stick one post to the Batt + on the alternator and ground the other.

Similar to this one.


mvphoto93175.jpg
 
(quoted from post at 22:01:44 06/12/22) You may be mistaken about just holding it near the alternator/generator. The ones I have saw had two post. One measured volts, the other amps. Or maybe either amps or volts. Dad had one two post that measured amps. Stick one post to the Batt + on the alternator and ground the other.

Similar to this one.


mvphoto93175.jpg
Dad had one two post that measured amps. Stick one post to the Batt + on the alternator and ground the other. " Call me a doubter
 
I have acquired several over the years. My original would test both starter draw and generator/alternator output just lay it on the wire, very handy. Should be available online or at a good auto parts store.
 
Amp, Incorporated built one back in the '80s I bought and still have. I was doing some work for a guy replacing his motors on his silos. Its for AC and is a clamp on.....a single wire of the supply-return circuit. The jaws (open and close around the wire) and are a single turn transformer primary and inside the handle is the rest of the transformer with a rectangular, multi-range needle indicator in the handle too...no external power needed for that. It also has Volmeter sockets and leads for reading voltage. I still have it in the tool box and still works like new.
 

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