We found this circuit in a 1965 magazine. The circuit can be assembled with current equivalent transistors and the precision in generating the frequencies depends on the tolerance of the capacitors.
This sensor works as an electronic push button, activating a power relay. The circuit must be...
This circuit is based on an old operational amplifier, having been found in documentation from the...
Found in a Maxim documentation, this 1980s circuit drives 4 LEDs on a bar scale. The circuit does...