Amp Gauge from old charger?

[coldspot]

HELLO_

I'm Building a control box and would like

to install an old Amp gauge. Salvaged from a dead

Battery Charger.

What I'm not sure about is wiring it up.

I need to NOT run the incoming HOT, (Pos)

straight thru it, but instead it should

be run paralell to this HOT wire using

good short wire to hook it up? (shunt?)

I just have not let any "Magic Smoke"

out of any thing in years and do not

want to let any out on this.

If anybody could PLEASE let me know

if I'm seeing the light or not.

I've been wasting all the power my mini mill

has been making on a couple of trailer

tail lights, stalling on the hook up

of the control system for fear of the magic smoke.

But am getting to many mills done and really need

to start using some of this stuff i've been

building and buying.

Amp gauge is after a heatsinked, (computer fan w/thermo sensor

extra for added cooling if getting to hot)

full wake bridge.

Another question about the bridge rec-

Running the Pos from DC PM minimill

thru the bridge on one of the AC in sides

should I also run the Neg thru this on the

other AC in side or can it just be hooked straight

to my "Pull to short" mill kill by shorting switch?

Also thinking about a "Bridge Box",

that I'll build and have each mill

run into for it's own bridge, (even if it

was bridged at mill on tower), then each

would be hooked to a bus-bar type of set-up

to combine the power before entering the

control box. This would be for my smaller

mills only, knowing that the larger ones

will need their own set-ups.

I"m also trying to figure out a way to

use the stepper micro mills combining together

for maybe a way to use this power.

A few thoughts are to series them for

lower volts with adding Amps.

Or maybe, paralell one with a mill that

dousn't get up to charging voltage in light

winds so the voltage will be there.

Any thoughts on this???

:|

[coldspot]

OOP'S

Brainfart

Micro mills

Wired paralell for adding amps

[willib]

coldspot , i also have a gauge to monitor amps .

my gauge uses about 0.2 milli amps full scale.

you will need some equipment to figure out the shunt.

do you have a ammeter with a milliAmp scale?

and a voltage source?

and some resistors?

you have to figure out the resistance of your gauge , mine is 4400 ohms .

once yo have a number for the resistance it is easy to calculate the shunt needed.

but you have to know the maximum current you will be reading.?

[Kwazai]

if i remember correctly an ammeter gets hooked parallel to the load..?

Mike

[jimjjnn]

Ammeter is connected in series. Voltmeter is parrallel.

[coldspot]

willib-

THANKS !!!

Equipment-

Fluke 23, (20+ years old but, has 10Amp{Fused} & 300mA DC settings).

El-Cheap-O, "PowerProCraft" # "DT-830B", ($3.95),

10ADC unfused, & 200u, 2000u, 20m, 200m DCA settings.

Voltage source, many computer power supply's and a

old train set power supply, (12VDC)

Resistors- Lots stripped from many things.

resistance of gauge=

On Cheap-O = 00.3 @ 200 Ohm setting

Fluke 23 = 00.5 @ Ohm setting, (used same cables from cheap-O)

Fluke 23 = 01.0 @ Ohm setting using fluke cables. (super nice

push to clamp jaws, newer than unit be still old 15+ years)

 "maximum current you will be reading"

I wish I knew.

Mini Mill =

Ametek 30 with 3 blades ceiling fan blades

But do have a couple more about ready to fly

Check my Diary

Thanks willib !!!!

[willib]

Did you notice the needle moving when you put the ohm meter on it?

i think you can use that as a source ,

if you can accuratly measure the current through the gauge and at the same time measure the voltage across the gauge , V/I = gauge restance.

this is what i would do , three instruments will be needed.

use one on the ohm scale to power the gauge .

use another to measure the current through the gauge

and a third to measure the voltage across the gauge..

[harrie]

Hi coldspot

I also have used a ampmeter rated at 15 amps salvaged from a old battery charger, and only had to run it thru the positive wire comming from the rectifires. did not need a shunt. I think all wires comming from the geney will need to run thru the bridge.

[coldspot]

Harrie-

yea, It's a 0 15 amp range one.

So, just run the full juice thru it, (Pos side).

And hook the other side of my gen, (Neg)

to the other ,(open AC) plug on my Bridge.

I don't really thing that needs to be done.

But also it wouldn't hurt anything if done that way.

I just wanted to hook the pos from another DC PM motor/Gen

to that extra plug.

 I know I'd better not run to large a one there but

to compliment the Ametek 30 VDC, I have a

24 VDC Servo motor just about ready to fly with it.

I also have a schottky Diode in the Control box

before the Charge controller, So there wilol be

no back feed to the bridge rec on the pos side.

I have the Amp gauge wired that way but was over thinking it.

THANKS

[terry5732]

Usually an ameter is wired through. If you hooked it across your source it would be a short. Your 15 amp meter is only going to allow a max of 15 amps though ( or so) before the smoke. There used to be an ameter at auto parts stores that you could just set against your batt cable. The only ones I've seen lately are antiques.

[coldspot]

"is wired through"

Thats the question I'm asking

Wired series, Pos running thru it

with neg no were around it.

Or

Wired paralell to the Pos,

So the full power isn't running thru it.

Like a shunt.  

??

[nanotech]

[coldspot]

Thanks nanotech

Thats a good diagram of the question I asked.