This gas sensor circuit was found in July 1976 Radio Electronics magazine. The TGS sensor was a common type at the time. Note the power supply to the circuit.
The power transistor of this circuit can also be the TIP42 mounted on a good heat sink. The...
Using a window comparator, this circuit trips over a certain range of input voltages. Formulas for...
This timer circuit was found in a 1980s documentation. The integrated circuit is the 555, which...