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.
The gain of this amplifier is 10 times and the excursion to the output voltage is 6.0 V (peak to...
The frequency of this circuit depends on the crystal. The transistor supports a modern equivalent. We...
This circuit uses the SQ3524, a switching integrated circuit. The circuit was found in the April...