Ammeter (CB9660E)

This current meter with many scales was found in a 80s American documentation. The operational amplifier is from that time, uncommon nowadays.

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Sensitive Metal Detector (CB4406E)
This circuit was found in a 1992 documentation and has excellent sensitivity, using components that...
Switching amplifier (CB9001E)
We found this circuit in an old American documentation. The circuit applies to modern equivalent...
Water Level Indicator (CB6268E)
This circuit was found in an English publication from the 80's. It triggers a buzzer (with...