Buffer for VFO (CB7282E)

This circuit was obtained in a Popular Electronics from the 90's. The gain depends on R4 and R3. Transistors are general purpose types.

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Sample and Hold (CB5953E)
This is the basic configuration of an operational amplifier sample & hold circuit. The FET and...
Triangular Oscillator (CB15684E)
The integrated circuit 4136 consists of operational amplifiers of type 741 in the same enclosure and...
Sophisticated LED VU meter (CB3831E)
We find this circuit in a 1987 publication. It makes use of comparators constructed around the 741...