Low temperature sensor (CB7814E)

Found in 90s Radio Electronics, this circuit is indicated for reading temperatures below zero.

NAB Equalizer (CB7307E)
This circuit was found in an American audio documentation from 1968. The configuration can be...
DC to DC converter (CB9673E)
This converter uses an SG1524 integrated circuit, which is uncommon nowadays. The circuit is from...
Overtone Crystal Oscillator (CB6184E)
This circuit was found on an 80's Ham Radio. The transistor admits equivalent. The circuit can...