Motorola suggests this circuit in an 80's documentation. The circuit uses an inverter to produce a higher voltage for 9 V battery charge from a single cell.
This circuit was published in a 1977 Radio Shack catalog. The PNP transistor may be BD135 and NPN...
Texas Instruments Standard Operational Amplifiers Texas Instruments makes available through Mouser...
This circuit produces an intermittent ring tone being triggered directly by the telephone line. However,...