This 1967 General Electric circuit makes use of an array of 3 (integrated) transistors for an amplifier stage. The circuit has a 500 mV output.
This TTL decoder circuit for PC ports was found in a document from 1992. The power supply can be...
This circuit is from an old Popular Electronics, but it can be easily implemented nowadays, even...
The basis of this circuit is a CA3130 operational amplifier. The transistor can be BC548, and the...