This circuit was found in a Motorola manual from 1968. As it can be obtained 20 V at 15 kHz from 120 V x 60 Hz. The components are of the time.
This thermometer, which uses common diodes as sensors, was found in a 1975 magazine -...
This circuit is from American documentation from the 70s. This configuration appears in this...
We found this Japanese commercial radio diagram of three transistors in a documentation of the...