The LH1605 integrated circuit is not a common component today. The circuit was found in the 1994 National Semiconductor Linear Applications Handbook.
This small experimental transmitter with the CK722 transistors was found in Radio Electronics...
The supply can be between 4 and 10 V in this circuit and R4 is necessary when the supply is less...
Other operational amplifiers can be used in this conventional filter that rejects only one...