Intercom gain remote control (CB6294E)

This circuit was found in a 1964 Electronic Design. The circuit can be implemented with equivalent modern transistors. Note the high supply voltage.

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Adjustable High Q Notch Filter (CB15815E)
We can implement this filter with more modern equivalent operational amplifiers, since the LM110 is...
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Divide-by-16 Counter - 4520 (CB176)
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