The circuit below is suggested by National Semiconductor in technical documentation on the LM3909. The circuit is powered by a single battery and has a very low consumption.
When the input of this circuit goes to high level, the LEDs start to flash alternately. The...
This circuit already uses an integrated circuit from the time. Note the different encapsulation of the...
This power charger was found in a 1990s issue of Popular Electronics. Integrated circuits must be...