Based on Texas Instruments documentation, this circuit is based on the BQ2000 a circuit used to power LEDs. The circuit can be used with lithium-ion batteries.
The frequency of this Pierce oscillator, found in 1969 documentation, depends on the crystal. The...
This simple timer with unijunction transistor was found in an old American technical...
Found in documentation from the 1960s, this power supply employs germanium diodes from the time....