We found this circuit in a 1968 General Electric publication. The circuit uses an SCR of the time, but any modern equivalent can be used. The relay must have contacts that support the horn current.
Found in National Semiconductor documentation from the 1990s, this circuit has a 10 kHz pass band...
This circuit generates low-frequency sinusoidal signals. The variable capacitor is dual and the...
This circuit was found in a Hands-On Elctronics from 1987. The field effect transistor admits...