This timer, like the previous circuits, uses a currently uncommon integrated circuit. The time is given by capacitor C1 and R2 which has the range of values indicated in the diagram.
This shield circuit was found in an American publication from the 80's. The triac is of low...
The Variable Frequency Oscillator (VFO) shown in the figure can generate signals in a frequency range...
This circuit was obtained from an 80's Radio Electronics. The circuit decodes “scrambled” or...