7492: Base-Twelve (÷12) Counter (Ripple, Not Presettable, Not Unit-Cascadable)

This is a divide-by-2 and a divide-by-6 counter in a single package. They may be used together as a divide-by-12 or separately. It ripple-counts in the BCD-up direction. Note the unusual supply pinouts. Note also the pin connections are not the same as the 7490 or 7493.

For a base-12 counter, weighted 1-2-4-6, enter via Clock 1 and jumper Q1 to Clock 2. The 0-Set inputs must be grounded for normal counting. The output is low for six counts and high for six.

The counter advances on the negative-going clock edge, The clock must be properly conditioned and made bounceless and noise free. If a conventional base-12 counter is needed, both 0-set terminals must be held at ground.

The counter may be reset to zero by bringing either or both 0-Set inputs positive.

An external jumper must be provided between counter halves. If entry is via Clock 2, and Q6 is jumpered to Clock 1, an unweighted counter with a different sequence results. Q1 becomes the most significant output and has a symmetrical square wave. This other connection also allows the use of the divide-by-6 section as a divide-by-3.

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