Through the TTL output this circuit can be used as a shield. The sensor is a platinum probe, and the operational amplifier can be replaced by a modern equivalent, preferably of low voltage.
This stage with polarization of only one resistor can use any general-purpose transistor. The...
This voltage-controlled potentiometer using an LDR was found in an English documentation. LDR is...
This interesting sensor for RF signals was found in an article in the June 1989 Radio Electronics...