This circuit also detects IR, providing LED indication. The circuit is used to indicate humidity in bench tests. We found it in the Radio Electronics magazine of February 1990.
We found this circuit in a 1976 documentation. The FET can be the BF245 and the bipolar transistor a...
This circuit is the receiver for the CB13997E. The transistor can be the BC548. We also found this...
We found this oscillator in a publication for radio amateurs from the 70s. The circuit generates...