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I'm really new to Proteus, so if I'm doing something very wrong, sorry.

I'm messing around with the Proteus simulation but I don't understand why my voltmeter has given me a value when the circuit is open. I expected it to give a 0 V result. I tried adding a ground to the negative connection of the Voltage source but it didn't help.

Here is my circuit, with the simulation running:

Circuit with a voltmeter connected to a switch and a voltmeter

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  • \$\begingroup\$ I am not sure what kind of model Proteus uses when emulating a switch, but in real life 1000V is quite a lot of voltage to put over a switch, so any impurities, moisture and ionized air between switch pins will cause conduction. Also the multimeter is not ideal, most multimeters have input impedance of roughly 20 Mohms when measuring voltages. \$\endgroup\$
    – Justme
    Feb 14, 2019 at 18:25
  • \$\begingroup\$ I though that in Proteus it would simulate a ideal circuit. I'm going to do a relay system that has to operate with 1000V so I wanted to simulate somewhere, but with this happening is quite difficult to be sure everything will work. \$\endgroup\$ Feb 14, 2019 at 19:17

1 Answer 1

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I think that's what we call "floating": as long as that wire is connected to nothing, you can't know what happens.

It's quite realistic: if you turn on a multimeter and don't connect the Plus-Pin anywhere, it will show values.

Multimeter showing a voltage with Plus-Pin not connected

To get around this, you can ensure that this wire is never connected to nothing by adding a resistor in parallel to the meter:

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ Well, not sure if this is working for me. When I use a resistor value of 10k it almost go to zero (0V) but when I use one with a higher value like yours it doesn't work. i.imgur.com/61vSxXa.png \$\endgroup\$ Feb 14, 2019 at 18:22

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