Freeze Alarm (CB14454E)

The circuit of a 1968 publication can be implemented with more modern transistors such as BC548 for NPN and BC558 for PNP.

Amplifier DC 2 (CB21903E)
This amplifier with two transistors for analog instruments was found in a Raytheon publication from the...
VFO With Ceramic Resonator (CB12454E)
Using a ceramic resonator, it is possible to vary the frequency between 4.9 MHz and 5 MHz. The...
Rejector Filter 741 (CB5195E)
This operational filter configuration was obtained in a 1980s publication. The calculation is made by the...