Found in American 90’s documentation, this circuit generates 300 Hz depending on the capacitors used. These components can be changed to obtain other frequencies.
The diodes of this circuit are general-purpose, and the base resistors are typically between 2k2...
This electronic Morse key was found in a Popular Electronics from the 90's. The components are common,...
This well-known oscillator configuration that produces a siren sound when pressing CH1 is from a...