Mini Megaphone (CB8952E)

Found in Popular Electronics' 90s, this small megaphone is based on LM386. The circuit uses a high impedance microphone.

230 to 2.8 kHz Adjustable High Pass Filter (CB12571E)
The cut-off frequency of the filter shown in the figure can be adjusted to values between...
Burglar alarm (CB7428E)
This circuit was found in a Popular Electronics from the 90s. The components used are all common...
MOSFET RF Oscillator (CB19562E)
This circuit uses a dual floodgate MOSFET not very easy to obtain today. Its handling is very...