The circuit is from the MC1539 manual, an operational one close to the 741. The transistor admits equivalent and must be mounted in a good heat sink.
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...