This resistance meter circuit was found in the February 1984 issue of Radio Electronics magazine. It is based on a digital module from that time. The power supply is 5 V.
When a small air current reaches the piezoelectric sensor, a small audio signal is generated and...
This circuit, from the 1977 GE semiconductor manual, uses a unijunction transistor beyond the...
The logarithmic response of this amplifier with operational is given by the presence of the...