Timer for enlargers (CB8301E)

From the time when photographs developed on paper could be enlarged, this circuit was found in a 1960s General Electric documentation.

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Amplifier for photodiode 1 (CB6787E)
We found this circuit in Harris' 90s documentation. The circuit applies to modern operational...
Crystal oscillator (CB7539E)
Found in a 90s magazine for radio amateurs, this circuit can generate frequencies up to 45 MHz...
Two Diode Balanced Modulator (CB4233E)
This is yet another balanced modulator circuit for SSB transmission. This two-diode circuit was...