This flasher circuit consists of an astable multivibrator with the frequencies given by the capacitors. The circuit is from 1965 using light bulbs, but LEDs can be used. Power comes from 4 batteries.
This circuit requires an input current of only 20 fA (femto amps) which corresponds to a...
In the figure we have a current source whose intensity is given by the formula next to the...
The circuit is from a 1978 publication and the transistor may be the BC558. The transformer is...