Contactless temperature sensor (CB7109E)

Found in an American documentation from 1968, this circuit senses the temperature through an infrared sensor of the time. The indicator is analog.

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Adjustable High Q Notch Filter (CB15815E)
We can implement this filter with more modern equivalent operational amplifiers, since the LM110 is...
Simple Stethoscope (CB18347E)
This stethoscope or amplifier for hearing aid using a crystal headset and microphone was found in a...
Divide-by-16 Counter - 4520 (CB176)
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