P1 on this Radio Shack circuit is a 6 V lamp with current up to 500 mA depending on Q2. The frequency is given by C1 which can have a modern standard value such as 3.3 uF or even 4.7 uF.
This circuit is from a Radio Electronics magazine from December 1958. The indicator instrument is analog...
This circuit sends signals to a shortwave radio (range 3 to 7 MHz) at a distance of a few tens of...
This circuit was found in an Electronics World of 1968. It can be applied to any modern triac and...