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volt/amp meter how to connect

79monte

Dec 4, 2023
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Could someone show me how to connect this? thanks for the help. I am trying to connect a voltmeter to my adjustable
power supply so I know the volts and amperage of the parts I am testing.
 

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Bluejets

Oct 5, 2014
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Show details of the meter and a link to specs where you bought it.

Also details on the range of the power supply voltage and current.
 

79monte

Dec 4, 2023
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sorry I forgot to mention the specs. The graymark power supply is adjustable from 0-16 volts
The volt/amp meter is adjustable from 0-100 volts, 10 amp. I did not get any paperwork with the
voltmeter I bought it off Amazon. I attached a screenshot of the voltmeter and a diagram of it. I hope it
helps.
 

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Bluejets

Oct 5, 2014
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From your supplied drawings.......
if you intend to drive the output from zero volts up to 16 volts, you will need and independant supply to power the display unit.
Then connect everything as in the lower diagram.
 

79monte

Dec 4, 2023
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Dec 4, 2023
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Could someone show me how to connect this? thanks for the help. I am trying to connect a voltmeter to my adjustable
power supply so I know the volts and amperage of the parts I am testing.

From your supplied drawings.......
if you intend to drive the output from zero volts up to 16 volts, you will need and independant supply to power the display unit.
Then connect everything as in the lower diagram.
independent power supply? you mean like a 9 volt battery? damn I thought I could have just connected it. I planned on using it to test things up to 12 volts only.
 

Delta Prime

Jul 29, 2020
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lol thanks I'm a car guy so electronics is not my first profession.
That's cool I like cars.
These little meters need to be isolated. meaning you can't power the meter, using the same power supply that you are measuring.
I bought mine when they first came out.
I threw it on the floor and crushed it into little pieces. Stupid meter, they do that on purpose. :mad:
 

79monte

Dec 4, 2023
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That's cool I like cars.
These little meters need to be isolated. meaning you can't power the meter, using the same power supply that you are measuring.
I bought mine when they first came out.
I threw it on the floor and crushed it into little pieces. Stupid meter, they do that on purpose. :mad:
lol I'm definitely always learning when it comes to electronics. I guess I figured with all the technology they
would have figured something better out by now.
 

Bluejets

Oct 5, 2014
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I guess I figured with all the technology they
would have figured something better out by now.
In defence of the unit, you need power to the display to make it work so by turning your variable down lower than 4.0v it simply will not work as a "one supply unit".
Nothing to do with the design being crap.
 

Harald Kapp

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I attached a screenshot of the voltmeter and a diagram of it.
The diagram shows all you need.
If the voltage you want to measure is > 4 V (and < 30 V), use the top diagram ("Share the power supply"). The supply power for the module will then be taken from the voltage source you measure.
I'm a car guy
So I assume you are using the meter mainly on 12 V, with the variablke power supply going down to maybe ~ 6 V to test circuits at very low voltage. In this case the connection as noted above is fully usable.
It will cease working only when you go below 4 V.


If operation below 4 V is required (and only in that case), then you need a separate power supply for the module. Connect it as shown in the lower diagram ("Independent power supply").
you mean like a 9 volt battery?
Possibly, but a 9 V battery will be drained rather quickly by the module (since the module uses an LED display, power consumption is comparatively high). A USB power bank at 5 V may last longer and is rechargeable. Or your variable power supply might have a separate voltage output, idk.

I figured with all the technology they
would have figured something better out by now.
Define "better".
A unit that in many cases doesn't need a separate power supply is not bad. It is also a physical necessity to provide power to the unit and this will require a minimum input voltage (4 V in this case). There's nothing wrong with that.
One surely could build a unit that draws less power using e.g. an LCD instead of the LEDs, then add a step-up power supply regulator, possibly an internal battery and/or some energy harvesting circuitry to span times when no external power is present etc. etc.
Is that better? It is definitely much more expensive and this will have many users deny the "betterness" of such a module.
 
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