LED AC Voltmeters & Ammeters

TYVM. 

Earlier in this thread I had reported purchasing digital AC ammeters with very small gauge wires.  I looked back on my eBay purchases hoping to find those but no luck. I did not keep those very long.  What I am using NOW are as shown in the attachment to this email.  The shunt is INTERNAL and the screw terminals can accommodate wires of reasonable size--I use #16.  This one has a blue background LCD display and sold for $11 each in early 2019, from vendor elite.element.  All AC ammeters must have a shunt, but some, like this one, has it internally.  Voltmeters do not use shunts.  An external shunt would be better in that a high current incident that results in a burnout would only damage the external shunt, at least theoretically.

You're right Gary. My external shunts are pretty robust. I don't think the shunt would fail. I see some ammeters with ring transistors that go around the wire. No power would actually be in circuit with the meter in that case. However, I could not find one with the right specs.

George

This is the spec sheet for the ammeter in your picture Gary. See pic. 

171358955425
ebay item number

Here’s the first video. Will be a week or two before it’s installed on the layout.

ronald weatherby posted:

This is the spec sheet for the ammeter in your picture Gary. See pic. 

Be advised that the spec sheets suggests this meter requires a 12V isolator instead of the 5V isolator as per the originally mentioned meter.

superwarp1 posted:

Here’s the first video...

I won't tell your boss... but is there any way to sneak in an engine to your office?

That is, I see you were comparing the readings to a bench meter with a resistive load.  But modern engines using DC motors present a non-resistive load.  So even if you apply a pure sine voltage, the current will be anything but.  It's kind of, sort of, like the chopped-sine voltage measurement problem where a basic AC voltage meter will under-report the voltage...and guys have even created conversion table cheat-sheets or whatever.

Likewise, a basic AC ammeter will also under-report the current if driving a non-resistive load.  And, again, I suppose one could come up with a cheat-sheet conversion table.  I'm imagining a discussion where some 10 Amp breaker keeps tripping even though the meter reads something less than 10 Amps.  I guess it depends on what the objective is.

The spec sheet is for a different meter than the one superwarp1 is showing in his video. It is for the one Gary L. was showing earlier that had screw terminals for the connections. Just to clarify. 

Gunrunnerjohn

My friend gippers alerted me to your post.

I've been looking forever, for readable, AC digital volt & amp meters in the 18V & 1-3 A range. Thanks for your knowable to the point discussion, and finding these gems. Since you could select the current i assumed there was a shunt present (but couldn't find in spec's) and those small gauge wires didn't give me a warm feeling. I've wondered about isolation as well. you've answered all the questions.

One thought:    I plan to install the meters on the INPUT side of the DCS- TIU to eliminate the possible corruption of the track's digital communication signal.

Second:    1 meter { VOLT or AMP } could easily be used for 2 Tracks with a double pole double throw 10 A bat handle toggle switch or a pair of meters, 1amp, 1volt could be used for 2 Tracks with 4 pole relays.

Third:    From "AutomationDirect" ice cube relays with 12-vac or 12-vdc coils W/ 15amp contacts and sockets available for convent wiring and mounting. they come with a manual activation lever and pilot light. The AC-volt coil cubes are { search on there site for- 781 = single pole, thru 782, 783, 784 = four pole } all for a reasonable price. Single pole $4.75 & Four pole $8.00. 

Thanks again    

Sorry delete second thought that will only work for volt meters. i took a very simplistic view unless we don't switch the comon side.