In electronics,how do I test which is positive and which is negative?
thanks! I have a multimeter, but not sure how to use it, and I dont want to solder the wires wrong!
Answer:
From your question I assume that you want to test the LED, BEFORE you solder it into the circuit.?
Then you don't have a voltage, and the "black lead / red lead story" may not be right. Because you will most like use the Ohm range on your multi-meter to test the LED's polarity, and you will find that on most (analog, battery operated) multi-meters, the polarity is reversed when you use the Ohm range!
The LED will have low resistance from "plus" to "minus" and a high resistance the other way around. But take a second multi-meter first to determine the polarity of your first multi-meter when you go into the Ohm X 1 range.
ok touch the leds to both ends if the display give you a negitive number you have them backwords and the other one is red(postive). Really easy even a cave man could do it.
my name is Jacob and I am running for President of the United States of America
Black leads are negative
Red leads are positive
If you put the black lead to earth you can check all voltages and polarity with your red lead. -ve or +ve Volts
measure thru your multimeter, set your multimeter to voltage and if you think that the voltage you are measuring is 12 volts you need to set your range to a much higher range . and then measure if your using digital meter if the reading have a negative sign that is reverse and if is analog meter the indicator will move to the left side means that is reverse. note that red probe is positive and the black is negative.
It varies depending on the circuit but it is usually clear from the design of the device or from the component details. Where polarity is a factor components will be marked either by a line, dot or other mark to show which way round they should be assembled this information is available from the component specification. The circuit board is likewise marked to ensure correct orientation. Its difficult to say how to test for polarity without knowing more about the circuit. If you are just talking about your multi-meter the common (black ) lead is negative and red positive.
The red terminal on the multimeter is always positive.
For a digital meter: If the voltage shown is positive (no negative sign in front of it), the red wire is connected to the positive side; otherwise the red wire is connected to the negative side.
For an analogue meter: If it gives a reading, the red wire is connected to the positive side. If the needle attempts to go backwards and wrap itself around the left-hand stop, the red wire is connected to the negative side.
Hi, The red cable is the positive and the black is the negative. If you put them across aa AA battery on DC say up tp 50volts the needle will go up to 1.5 volts. If it tries to go anticlockwise then the leads are mixed up. look at the + - indication on the battery this will confirm which lead is positive when test is carried out if you dont have colour coded leads. good luck
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Answer:
From your question I assume that you want to test the LED, BEFORE you solder it into the circuit.?
Then you don't have a voltage, and the "black lead / red lead story" may not be right. Because you will most like use the Ohm range on your multi-meter to test the LED's polarity, and you will find that on most (analog, battery operated) multi-meters, the polarity is reversed when you use the Ohm range!
The LED will have low resistance from "plus" to "minus" and a high resistance the other way around. But take a second multi-meter first to determine the polarity of your first multi-meter when you go into the Ohm X 1 range.
ok touch the leds to both ends if the display give you a negitive number you have them backwords and the other one is red(postive). Really easy even a cave man could do it.
my name is Jacob and I am running for President of the United States of America
Black leads are negative
Red leads are positive
If you put the black lead to earth you can check all voltages and polarity with your red lead. -ve or +ve Volts
measure thru your multimeter, set your multimeter to voltage and if you think that the voltage you are measuring is 12 volts you need to set your range to a much higher range . and then measure if your using digital meter if the reading have a negative sign that is reverse and if is analog meter the indicator will move to the left side means that is reverse. note that red probe is positive and the black is negative.
It varies depending on the circuit but it is usually clear from the design of the device or from the component details. Where polarity is a factor components will be marked either by a line, dot or other mark to show which way round they should be assembled this information is available from the component specification. The circuit board is likewise marked to ensure correct orientation. Its difficult to say how to test for polarity without knowing more about the circuit. If you are just talking about your multi-meter the common (black ) lead is negative and red positive.
The red terminal on the multimeter is always positive.
For a digital meter: If the voltage shown is positive (no negative sign in front of it), the red wire is connected to the positive side; otherwise the red wire is connected to the negative side.
For an analogue meter: If it gives a reading, the red wire is connected to the positive side. If the needle attempts to go backwards and wrap itself around the left-hand stop, the red wire is connected to the negative side.
Hi, The red cable is the positive and the black is the negative. If you put them across aa AA battery on DC say up tp 50volts the needle will go up to 1.5 volts. If it tries to go anticlockwise then the leads are mixed up. look at the + - indication on the battery this will confirm which lead is positive when test is carried out if you dont have colour coded leads. good luck
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