Abstract: A handset for a telephone set is provided with a receive amplifier which is compatible with both electronic and electro-mechanical telephones, that is telephones having electro-mechanical transmitters and telephones having electronic transmitters. The operational amplifier is powered from the telephone line, from the power input to the telephone network, and is driven via an impedance matching circuit exhibiting a low AC impedance and having a capacitor to short out AC signals such as voice signals on the telephone line and a special transistor which has high AC impedance and low DC resistance to block out AC signals and provide DC power. The operational amplifier is of special characteristics, stabilized to work down to very low voltages, e.g. 1.1 volts and also capable of operating at higher voltages, e.g. 20 volts.