Multipurpose temperature control (CB21368E)

This circuit was found in a 1967 RCA SCR manual. It uses period components that can be replaced with modern equivalents.

Field intensity meter (CB7563E)
Found in a magazine 73 for radio amateurs, in a 90's edition, this circuit uses a general-purpose FET...
12V Lamp Flasher LM3909 (CB14284E)
The selected circuit causes a 12 V lamp with a current of up to 500 mA for the BD135 transistor to flash at...
Schmitt Trigger with 555 (CB25527E)
This is one of the many applications of the 555. We found it in the November 1992 Radio...