This circuit was obtained from an 80's Radio Electronics. The circuit decodes “scrambled” or sinusoidal encoded signals by providing an audio signal at the output.
This circuit is from an 80's documentation. The BC108 can be replaced by the BC548 and the 2N3055...
May 2017 - These new Digital to Analog converters from Texas Instruments, available from Mouser...
This circuit prevents the passage of frequencies in a range starting at 1 kHz and can be adjusted...