We found this circuit in an old Mullard (Philips) documentation on the 555 and 556 integrated circuit (double 555). The relay must be 12 V with contacts that support the horn current.
This circuit with only one transistor was obtained in an old English documentation and can be...
This circuit uses a transistor as noise source and a 741 IC as amplifier, sourcing a high...
This circuit uses an LED (called SSL) to regulate current in a configuration with complementary...