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How do you figure out polarity for some salvaged circuit components, like resistors, etc? Answered

I took some resistors off a board and noticed that the board said positive at one lead but I didn't pay attention so how do I figure out which is which

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Phil BBest Answer (author)2009-05-01

An electrolytic capacitor has polarity and it is indicated on the capacitor with "- - - - - -" or "+ + + + +" down the side near one of the leads. A diode has polarity and has a solid band to indicate the "+" end. If the component is a resistor, there might have been a "+" on the board to indicate that lead was positive with respect to ground so a technician can troubleshoot the circuit, but that would concern the circuit and not the component.

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static (author)2012-01-15

Uh... The band on a diode indicates the cathode, the negative terminal. I have never seen or read of a board marked with a "+" to indicate anything for a resistor. Unnecessary because the lead connected to ground isn't going to show a voltage potential.

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The Lightning Stalker (author)2009-08-13

For transistors and ICs, there are thousands of datasheets at Datasheet Catalog.

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NachoMahma (author)2009-05-01

. Resistors don't have polarity. The + was for another component.

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phillyj (author)NachoMahma2009-05-02

On a closer look, the + is more likely for the capacitor next to the resistor. Thank guys. Both answers were helpful

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