Electronics > Beginners

Voltmeter for negative voltage

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BravoV:
Aware you're working on the switch, but just a thought, why not buy something like this ? Imo, its relatively cheap, and can do positive & negative readings and it works.

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... and different colors too ..   :P

perieanuo:

--- Quote from: BravoV on December 07, 2018, 07:48:28 am ---Aware you're working on the switch, but just a thought, why not buy something like this ? Imo, its relatively cheap, and can do positive & negative readings and it works.


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hi,
it's more interesant to buy a VAmeter for a variable PS, you got crt and voltage in one location, 10 times easier to cut only one rectangle.
just do the right wiring that's all.he already had 1 better device, not the same precision maybe but that's not the point
pierre

fsr:

--- Quote from: perieanuo on December 07, 2018, 06:37:24 am ---
--- Quote from: fsr on December 06, 2018, 11:44:20 pm ---I don't think that you can use this meter even if you had two of them, because you need to connect the ammeter over the negative wire, but this is a split supply, so just imagine what will happen if you have two 1A loads, one on the positive side, and other in the negative side: the current over the GND wire will be 0A.

Are you interested in a future meter project? Maybe you could "arduino" a meter. There are some small arduino boards out there, or you could use the "naked" atmega328 on your own board.

--- End quote ---
Have you understood my schematic?positive branch measures load crt by interposing secong gnd point, in negative branch wiring same thing happens and current resistor inside ammeter is on negative input...


Envoyé de mon iPad en utilisant Tapatalk

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Yes, you put the ampmeter on the GND line when measuring the positive side of the supply. But the current on the GND line is the sum of the currents of the positive and negative sides (and the currents go in opposite directions, so they substract). KCL.
1A of current on the positive side - 1A of current on the negative side, and the ampmeter on the GND wire will read 0A.
I think that he needs to find some meters that can be installed on the + and - wires.

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