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.
The maximum frequency of the oscillator shown in the figure is around 3 MHz. The trimmer adjusts the...
This circuit was obtained in a 1977 Radio Handbook. The transistor is from the era and the coils...
August 2017 - STMicroelectronics' BlueCoin development environment is available at Mouser...