Amplifier and controlling apparatus operating from a unipolar power supply

An apparatus for operating from a power supply having a first voltage of a first magnitude and first polarity, to amplify signals, characterized by:

• an amplifier for amplifying signals presented to an input terminal thereof and providing amplified signals to an output terminal thereof, the amplifier having a first power lead and a second power lead;
• a power conditioning circuit for coupling to the power supply and the amplifier, for generating from the first voltage a second voltage of the first polarity and a third voltage of opposite polarity, wherein at least one of the second and third voltages has a magnitude greater than the first magnitude;
• a switch coupled in series with the amplifier between the first power lead of the amplifier and a connector of the power supply and wherein a portion of the third voltage is coupled to the second power lead of the amplifier;
• and
• a control circuit for operating the switch and having therein, (i) a circuit for energizing the switch in response to a turn-on signal, and (ii) a circuit for sensing whether the opposite polarity is present on the second lead of the amplifier and, if the opposite polarity is not present, disabling the switch, despite the turn-on signal.

An apparatus for operating from a power supply coupled to first and second connections between which appears a first power supply voltage of a first polarity and a first magnitude, to operate an amplifier, wherein the amplifier has an input terminal, an output terminal, a first power terminal and a second power terminal, the apparatus being characterized by:

• a power conditioning portion coupled to the first and second connections and to the second power terminal for generating from the first power supply voltage, a second voltage of the first polarity and a third voltage of an opposite polarity, wherein the second voltage has a magnitude greater than the first magnitude;
• a switch coupled in series with the amplifier between the first power terminal of the amplifier and the first connection;
• and
• a control portion coupled to the power conditioning portion for operating the switch and having therein a circuit for energizing the switch in response to a turn-on signal.