This circuit was found as part of another project in a January 1988 Radio Electronics magazine. The frequencies are given by the timing capacitors.
An advanced motor control software plug-in for Microchip’s MPLAB® X Integrated Development...
This relay without lock uses a general-purpose transistor. The relay is according to the supply....
This signal follower is from a 1970's documentation. So it uses the traditional configuration at the time...