This circuit with two 555s was found in the Encyclopedia of Electronic Circuits volume 5 of 1995. The power is high due to the use of 2N3055.
The filter shown in the figure, using only an operational amplifier, is characterized by allowing 1...
Found in a 90s American documentation, this circuit can be used as a shield, just change the...
Found in a Philips' 1968 documentation, this circuit is slightly different from the previous one. The...