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, suggested by an Electronics World of 1969, keeps a blinking LED for a while when a...
This is a Philips commercial circuit from the 90s. The integrated circuit must have a good heat...
This circuit converts a signal from any waveform into a rectangular or square signal of the same...