1st Gen Lunchtable Thread - General Discussion

Old mechanical meters are sweet.

Just be careful with the voltage vs current thing. The mechanical movements I've used in the past operate on current, and if you just put a straight voltage across them you'll burn them up.

And if you run out of luck with GE, simpsons are also sweet:
https://www.ebay.com/sch/i.html?_fr...Desc=0&_osacat=0&_odkw=simpson+electric+meter

 

Those meters do require a mA current to drive them, the shunt applies a mV voltage to the meter, and based on the meter winding resistance, a mA current will flow through the winding. For example for a 100A DC ammeter requiring a 50 mV shunt, a 10 ohm meter winding resistance with 50 mV applied would cause 5 mA to flow to make the meter go full scale (I=V/R).

 

This would be Miguel

 

Yep, exactly.

 

Or Tyler, after a few Whiteclaw

 

"roooooo wanna fucconme???" (or something like that he said when he jumped outta the trunk)

 

Are you the guy I talked to once on here about Simpson 260 meters? lol great meter

 

Maybe? I dunno. I only know about them because they're basically essential equipment for railroad signalmen because they're analog.

 

@davidstacoma

So what I'm building is a 120vAC > 100A 12vDC inverter to power about 10 halogen and LED emergency lightbars. Basically I'll have multiple banks of switches that operate the various functions on the lightbars.

The ammeter I know you wire in series with the load, and the shunt just brings the voltage down enough so it (doesn't blow the meter? I don't know much about shunts except they act as a resistor). As for the vDC meter, is that as simple as wiring in parallel with the load? Or do I need additional stuff to make it work.

This is a rough schematic:

 

Sounds familiar.. I think we discussed the fact that the low impedance of the Simpson 260 was great to load down stray voltages induced over wires compared to the new high impedance DMMs. Or maybe that was someone else.

 

Gawd damn cows are in the hay field already, gonna have to change deer hunt tactics probably.

 

@Wulf 's Tacoma

https://www.instagram.com/p/CCyXrWZpM9g/?igshid=1a42li3wpsdng

 

Jebus Christ

 

Not bad work there! Just put your 0-30V meter across the 12-13V output of the inverter, you show it connected to a dead short as drawn. And you need to fuse your circuits as well.

 

Hmmm. Ammeters in a DMM are a very low impedance, and if hooked up as the GE one is there, would just bypass the shunt resistor and blow a fuse. I'm not certain what the correct wiring is, but I'd want to be before I plugged that monster in. 100A through that meter might be exciting.


What are you using to get 100A at 12V? Those kinds of supplies are usually pretty spendy. It might be more cost effective to break it down into multiple lower power systems.

 

Lemme just keep posting spam in the middle of your convo

 

Is the short where I didn't connect the lines for the meters to the load? Sorry for the dumb questions, I haven't been formally trained on this stuff - just working off experience haha

 

Keeps the rest of us coming back

 

@Speedytech7 see I can progress on things.





see you in another 2 years taco

 

I collect emergency vehicle lightbars, they draw a great deal of amps. Especially the old halogen ones from the 70's to early 2000's. My Code 3 MX7000 draws about 32 amps in full code.

I'm using an RV battery charger for this, here it is on eBay:

https://www.ebay.com/itm/RV-Convert...battery-Charger/283325214123?var=584230368941

As for the amp meter, I don't even know if I drew it correct on that schematic. I was going off a google image of an example of one.

I know the shunt has four terminals, two for continuous load, and two that have the stepped down voltage that feeds the meter. Wasn't sure how to draw it.

What I am concerned about is, can the vDC meter handle 100 Amps? I can't seem to find any information on that.