This two-digit timer was found in the 1983 Special Projects issue of Radio Electronics magazine. The circuit uses components that can still be found today.
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...