Audio Kits
Preamplifier scanner
This circuit scan all the preamplifier entries to identify where is a audio signal and that entry remains selected. After a sign of signal absence, scanning resumes. Scanning action is supported by rectangular signal generator IC2c. Scanner’s entries are connected to the audio entries from volume control board of the preamplifier.
Useful signal is [...]
Electronic mosquito
The circuit behaves like a true mosquito: once the light dims, the mosquito starts an annoying buzz. When its light again it becomes mute, so that, as in the case of genuine mosquito is very difficult to spot.
Tension from pin 2’s IC1a determines if mosquito is active or not. The level of this [...]
Squelch schematic
Squelch is a circuit that acts to suppress the audio (or video) output of a receiver in the absence of a sufficiently strong desired input signal. This squelch circuit is simple and has an amplification for sufficiently large to be incorporated into an assembly of automatically control from a wide range of radio receivers. [...]
