This sensitive three-transistor circuit was found in Electronics Now magazine and is earphone-readable. The tuned range depends on the coil.
This circuit uses a common diode as sensor. The output goes from 0 to 10 V with the temperature change in...
This circuit is more elaborate than the previous one. It was obtained from an 80s circuit manual. The...
This interface or shield circuit for instrumentation was obtained in a publication from the 90's....