Found in old American documentation, this circuit can use crystals between 27.5 and 33 MHz operating on the third harmonic. The transistor admits equivalent.
The operational amplifier used in this project no longer exists, but the circuit can be adapted to...
With S1 closed, when dark, the triac will supply the load with the power set in R4. The LDR is...
Toshiba LDO Regulators Toshiba has a wide variety of low voltage drop (LDO) linear regulators...