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

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.

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.

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

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