This circuit was found in an Electronics World of 1966. It has a range of 5 to 25 000 Hz at 1 dB and the diagram includes the power supply.
We found this circuit in a European publication from the 1980s. The circuit uses a low impedance...
This simple circuit was found in Popular Electronics from the 1980s. The circuit uses an LED as an...
This circuit was obtained in a 1973 publication. The circuit uses two operational amplifiers to...