## Monday, February 20, 2023

How to convert a voltmeter to an ammeter?

A voltmeter measures the voltage drop between two points in a circuit. It tends to be connected to the circuit in parallel, and has a high resistance so as not to usurp current from the circuit. One of the current measurements between two ammeter points. They tend to be in series and have low resistance, so as not to affect the circuit's electron flow significantly. Both devices are galvanometers - a device that quantifies how much a spring-loaded electromagnet (powered by circuit current) steers with a permanent magnet. The details of how to convert an ammeter to a voltmeter vary with the design of the ammeter, for example how to physically get into it and how to change its parts, but the fundamental changes are the same patterns throughout - at least for the type analog.

Instructions

1 Insert a resistor in the internal circuit. This reduces the amount of current through the voltmeter itself, so that it does not significantly affect the circuit being measured.

2 Remove any parallel shunt resistor the ammeter may contain. These are included in ammeter to maximize current flow through ammeter. In other words, most of the current flows through the low-resistance parallel resistor, and the little that flows through the galvanometer registers current as it translates to current through the shunt resistor, which presents resistance negligible.

3 Replace the permanent magnet or spring on the solenoid to achieve the desired volt range. Use the following equality to help: NIAB = ??. Here, the left side is the magnetic torque on the gauge needle holding electromagnet. The right side is the spring torque opposite the deflection?. A is the area of the electromagnet coil, i is the current through the N wire loops of the electromagnet, B is the stength of the permanent magnetic field, and ? is the force constant of the spring. So if the needle range is, say, 30 degrees, then? = 30 degrees for the current, i, which is the maximum voltage drop, V, across the voltmeter that you want the meter to be able to register. You find i of V by defining the resistance R = V / i, and varying the resistance R of the voltmeter to get the desired voltage range.

4 Replace the current units on the gauge with voltages, according to your calibration in step 5.

Tips and Warnings

You may have some concern that the voltmeter will have too little current flowing through it, relative to the current the ammeter knows, to register much of the reading if you add a large resistor in series. But keep in mind that the ammeter's electromagnet had little current flowing through it because most of the current was going through the shunt resistor, which had such a low resistance.

How to convert a voltmeter to an ammeter?

A voltmeter measures the voltage drop between two points in a circuit. It tends to be connected to the circuit in parallel, and has a high resistance so as not to usurp current from the circuit. One of the current measurements between two ammeter points. They tend to be in series and have low resistance, so as not to affect the circuit's electron flow significantly. Both devices are galvanometers - a device that quantifies how much a spring-loaded electromagnet (powered by circuit current) steers with a permanent magnet. The details of how to convert an ammeter to a voltmeter vary with the design of the ammeter, for example how to physically get into it and how to change its parts, but the fundamental changes are the same patterns throughout - at least for the type analog.

Instructions

1 Insert a resistor in the internal circuit. This reduces the amount of current through the voltmeter itself, so that it does not significantly affect the circuit being measured.

2 Remove any parallel shunt resistor the ammeter may contain. These are included in ammeter to maximize current flow through ammeter. In other words, most of the current flows through the low-resistance parallel resistor, and the little that flows through the galvanometer registers current as it translates to current through the shunt resistor, which presents resistance negligible.

3 Replace the permanent magnet or spring on the solenoid to achieve the desired volt range. Use the following equality to help: NIAB = ??. Here, the left side is the magnetic torque on the gauge needle holding electromagnet. The right side is the spring torque opposite the deflection?. A is the area of the electromagnet coil, i is the current through the N wire loops of the electromagnet, B is the stength of the permanent magnetic field, and ? is the force constant of the spring. So if the needle range is, say, 30 degrees, then? = 30 degrees for the current, i, which is the maximum voltage drop, V, across the voltmeter that you want the meter to be able to register. You find i of V by defining the resistance R = V / i, and varying the resistance R of the voltmeter to get the desired voltage range.

4 Replace the current units on the gauge with voltages, according to your calibration in step 5.

Tips and Warnings

You may have some concern that the voltmeter will have too little current flowing through it, relative to the current the ammeter knows, to register much of the reading if you add a large resistor in series. But keep in mind that the ammeter's electromagnet had little current flowing through it because most of the current was going through the shunt resistor, which had such a low resistance.