This circuit is from an old Japanese publication of 1962. The circuit uses two batteries, one for the filaments of the tubes and the other one of high voltage for the plate circuits.
This solar cell driven circuit makes 4 LEDs run at a speed given by capacitor C2. The circuit is...
The time obtained in this circuit, from a 1978 publication, depends on R3 and C. R3 can have...
The duty cycle of a Schmitt Oscillator can be programmed by R1 and R2 in this circuit. The...