Astable 555 (CB21101E)

This 50% duty cycle configuration was found in a Popular Electronics from the 1990s. The operating frequency is given by C1.

Digital Volume Control with PIC (CB17627E)
This circuit is an excellent application for the PIC in audio, but the reader who intends to do...
10 W amplifier (CB9905E)
To a 16-0hm load, this amplifier provides a power of 10 W. We found this circuit in a Motorola...
TTL Output Magnetic Reader (CB14249E)
This reader with TTL logic compatible output uses an LM139 comparator. The circuit was found in...