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 simple MW radio was found in a 1975 publication, but it can be mounted with BC548...
The coil and sockets of this circuit found in a QST depend on the frequency band that is intended...
The 4066 is better than the 401 B because the 401 B has a lower internal resistance when the...