Signal Tracer and Capacitor Tester (T1241E)

This mains powered two-in-one instrument was found in a Radio Craft from March 1948. The headphone must be high impedance.

Non-Inverting Amplifier (CB20172E)
This amplifier circuit for instrumentation was found in the manual of the used integrated circuit...
TTL Beep-Beep (CB14033E)
We found this circuit in a 1986 Elettronica Pratica magazine, but the components used are common. As...
High current buffer (CB7280E)
Suggested by Popular Electronics, it is a digital amplifier, for pulses with frequencies up to a...