Hey,in this instructable I would show you how to make an analog voltmeter with correct readings . Working on principal of magnetic force generated by electricity.With this clever idea,you don't need to buy a new voltmeter when broken .Just take the material and make it yourself A voltmeter is an instrument used for measuring electrical potential difference between two points in an electric circuit. Analog voltmeters move a pointer across a scale in proportion to the voltage of the circuit; digital voltmeters give a numerical display of voltage by use of an analog to digital converter.Her's a video of its working:-

Step 1: Things Required to Make Voltmeter

Things required to make it are :-

  1. old broken voltmeter board (not working)
  2. testing wires with voltmeter
  3. nail
  4. insulated wire
  5. needle
  6. stripped wire
  7. duct tape

Tools required :-

  1. Scissors
  2. cutter
  3. pliers
  4. soldering iron with solder

Step 2: Taking Out Port for Meter

Take the circuit board of voltmeter or multi-meter and then with the help of pliers .Apply that much force ,so that the boundary of two ports must get separated from the board and make sure that the ports don't break apart from each other.

Step 3: Makaing Electromagnet

Our goal here is to make a simple electromagnet that can pick up objects made of iron or steel, without using a magnet.

1. Wrap the nail with the copper wire by coiling around it with the loops as close as possible, the more loops you add, the greater the magnetic force generated by the circuit.

2. Try out your magnet by holding the wrapped nail nearby iron objects, see if it picks up them, if it does, then congratulations, you've got a working magnet!

(The bolt becomes magnetic once a current is applied to the coil wrapped around it because electric currents produce magnetic fields. If the wire is wrapped around a coil, the magnetic fields will be concentrated in the loops, which is strengthened when its wrapped around a core, normally the atoms in iron or steel are pointing random directions, but when a current is applied to them, they line up pointing in one direction, and their magnetic fields will add up to create a larger magnetic field that attracts objects, eventually if you give it enough time, the bolt will become permanently magnetized and changing the electric current won't affect it anymore.)

Step 4: Functioning

A moving coil can be used as a voltmeter.The voltmeter has a coil of fine wire suspended in a strong magnetic field. When an electric current is applied, the interaction of the magnetic field of the coil and of the stationary magnet creates a torque, tending to make the coil rotate. The torque is proportional to the current through the coil. The coil rotates, compressing a spring that opposes the rotation. The deflection of the coil is thus proportional to the current, which in turn is proportional to the applied voltage, which is indicated by a pointer on a scale.Moving-coil instruments with a permanent-magnet field respond only to direct current. Measurement of AC voltage requires a rectifier in the circuit so that the coil deflects in only one direction. Moving-coil instruments are also made with the zero position in the middle of the scale instead of at one end; these are useful if the voltage reverses its polarity.

Step 5: Setting Up the Pointer

Piece a hole in cardboard and then hold the needle hole just above it and afterwards insert a thin wire through it and then make it movable using the wire a stationary and the needle moving.

Step 6: Fix the Electromagnet Near the Needle

Place the electromagnet leaving an inch space from needle in opposite direction and fix it using the duct tape . The electromagnet should be fixed strongly otherwise it can show wrong results.

Step 7: Insert the Ports

Pierce two holes according to size of ports in the cardboard . And now you can insert the ports in the two holes .Fix it with with glue/duct tape from upper side.

Step 8: Joining Terminals to the Ports

Take a pair of copper wires and roll around the two ports .Solder it after placing instantly.

Step 9: Join the Terminals of Electromagnet to the Port Terminals

Just join and solder the two terminals of the ports to the the terminals of electromagnet .!The two different terminals should not make contact with each other!

Step 10: Make and Join the Box

Make a rectangular box .Join it from all sides but only leave from the needle part for the reading visibility .After making box sides ,join them with duct tape and make scale from inside of box or outside of box.

Step 11: And It Works!

I've already shown a video in Introduction it is showing all about its working .Now just insert the voltmeter wires and be a scientist .It is really a helpful and waste reducing device .


You mentioned not to connect the two ports together. but that's basically what you're doing since your electromagnet is just a length of wire.
Very cool and simple but I have to say it seems dangerous. It also won't work in many situations. <br><br>Your device doesn't have a high input impedance like a voltmeter is supposed to. More wraps in the coil will increase the resistance but not to the order of millions of ohms. So, if you test a fresh battery against an old battery you might get good readings. But if you're measuring on a live circuit, this thing is going to suck a bunch of current from the circuit and ruin the readings. In addition, the coil might get extremely hot if a high enough voltage is being measured, so maybe cardboard isn't the safest option. <br>I like the fact that this is technically a voltmeter for probably less than a dollar in parts. But it really could be unsafe, especially for people new to electronics, and you should really think about changing or removing this article in my opinion
<p>This is really great project for kids to learn about electronic. </p>
<p>A great 'invention'! I'll soon be making one of my own. Thanks for inspiring me! All the best! =D</p>

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Bio: Thank you instructables!!
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