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.
Operatives used in this 80's configuration are not common today, but it is valid for modern...
The 5 outputs of the internal 4018 integrated flop flops can be used simultaneously for the...
This voltage-controlled potentiometer using an LDR was found in an English documentation. LDR is...