Relays up to 100 mA can be driven by the 555 with the recommended circuit. The circuit is from an article in the September 1992 Radio Electronics magazine.
The transistors are 2N918, 2N3464 and other RF equivalents of the time for Q1. For Q2, 2N3399, 2N2894...
This circuit, which can be used as a shield, was found in a 90s Electronic Design. The circuit...
This interesting intercom circuit was obtained from an Argentine publication from the 1970s....