How to Use a Multimeter to Test a Solder Joint

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An electronic meter (multimeter) is used to determine the test of the joint, but it is important that the weld joint is done properly, that it looks good, all clean and shiny so that the test can be done easily.

To check the weld joint continuity, first, set your multimeter in continuity mode so that the direction of the sound waves goes from left to right in a cone shape. Touch the two wires together and a beep will sound.

Now touch both terminals on the opposite sides of the weld joint. As a result of the continuity, the multimeter will beep, so you can say that it is one of the best multimeter among others.

The Usage of Fuse in the Circuit

Ammeters are generally protected from the excessive current by means of a small fuse located inside the meter housing.

If the ammeter is accidentally connected across a substantial voltage source, the resultant surge in current will “blow” the fuse and render the meter incapable of measuring current until the fuse is replaced.

Be very careful to avoid this scenario! You may test the condition of a multimeter’s fuse by switching it to the resistance mode and measuring continuity through the test leads (and through the fuse). On a meter where the same test lead jacks are used for both resistance and current measurement, simply leave the test lead plugs where they are and touch the two probes together. On a meter where different jacks are used, this is how you insert the test lead plugs to check the fuse:

Build the one-battery, one-lamp circuit using jumper wires to connect the battery to the lamp, and verify that the lamp lights up before connecting the meter in series with it.

Then, break the circuit open at any point and connect the meter’s test probes to the two points of the break to measure current.

As usual, if your meter is manually ranged, begin by selecting the highest range for current, then move the selector switch to lower range positions until the strongest indication is obtained on the meter display without over-ranging it. If the meter indication is “backward,” (left motion on analog needle, or negative reading on a digital display), then reverse the test probe connections and try again.  When the ammeter indicates a normal reading (not “backward”), electrons are entering the black test lead and exiting the red.

This is how you determine the direction of current using a meter. For a 6-volt battery and a small lamp, the circuit current will be in the range of thousandths of an amp, or milliamps. Digital-meter often shows a small letter “m” on the right-hand side of the display to indicate this metric prefix.

Try breaking the circuit at some other point and inserting the meter there instead. What do you notice about the amount of current measured? Why do you think this is?

Connecting an Ammeter to a Breadboard Circuit: Pros Tips and Tricks

Students often get confused when connecting an ammeter to a breadboard circuit. How can the meter be connected so as to intercept all the circuit’s current and not create a short circuit? One easy method that guarantees success is this: Identity what wire or component terminal you wish to measure the current through.

Pull that wire or terminal out of the breadboard hole. Leave it hanging in mid-air. Insert a spare piece of wire into the hole you just pulled the other wire or terminal out of. Leave the other end of this wire hanging in mid-air.

Connect the ammeter between the two unconnected wire ends (the two that were hanging in mid-air). You are now assured of measuring the current through the wire or terminal initially identified.

Again, measure the current through different wires in this circuit, following the same connection procedure outlined above. What do you notice about these current measurements? The results in the breadboard circuit should be the same as the results in the free-form (no breadboard) circuit.

Experiment Results

Building the same circuit on a terminal strip should also yield similar results: The current figure of 24.70 milliamps (24.70 mA) shown in the illustrations is an arbitrary quantity, reasonable for a small incandescent lamp.

If the current for your circuit is a different value, that is okay, so long as the lamp is functioning when the meter is connected. If the lamp refuses to light when the meter is connected to the circuit, and the meter registers a much greater reading, you probably have a short-circuit condition through the meter. If your lamp refuses to light when the meter is connected in the circuit, and the meter registers zero current, you’ve probably blown the fuse inside the meter.