I have a circuit (on paper, at least) that drives a relay via a transistor. The relay coil is nominal 6V (works from 4V to 8V). The supply voltage that is being switched into the relay coil by the transistor is is unknown, somewhere between 4 and 15 Volts. Obviously that becomes a problem if it happens to be over 8 Volts.
I have to find a way to "regulate" the voltage so that it doesn't exceed the 8 Volts. My first thought is to put a resistor in series with the coil, and then bypass that resistor if the supply voltage is low. Is there some other way? The solution has to be dirt cheap, like under 50 cents.
I have to find a way to "regulate" the voltage so that it doesn't exceed the 8 Volts. My first thought is to put a resistor in series with the coil, and then bypass that resistor if the supply voltage is low. Is there some other way? The solution has to be dirt cheap, like under 50 cents.