Shift register sequencer circuit

Posted on Feb 7, 2014

I was particularly enamored over the mechanics of the Quantized Random Voltage function. The thought occurred to me that, instead of having fixed quantization steps for each output of of the 4006 shift register, it might be fun to actually make the voltages adjustable through pots. The Quantized Random Voltage function uses a pseudo-random sequence, which naturally would repeat after so many steps. In order to make the function more random and less pseudo-random, I turned to Ken Stone's gated comparator idea so that a signal input could be used to derive high or low bits in the shift register. I then enabled the register to loop a stored number of high and low bits ad nauseum through a simple switch setup that routed the output of the shift register back to the input.

Shift register sequencer circuit
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But, if switches were arranged on the parallel inputs of a CD4034, then one could save any pattern by setting the switches high or low, and one could use the LED display to determine which bits were high or low at any given time. It wasn't until a bit later that the fact dawned on me that the switches could be used to "program" the Klee instead of relying on random data input. This was a watershed moment in how I regarded the Klee Sequencer - random input programming from that point on was really just a small "feature" of the larger Klee functionality. Another vital element introduced by the bit-for-bit parallel outputs of the CD4034 was the ability to apply each of the outputs to its own pot. The original Shift Register Sequencer had only four pots tied to the outputs that processed the sixteen bit register as it cycled through. Klee Breadboard Later On The CD4006 has a much larger internal shift register than the CD4034; the CD4006 shift register can be up to 18 bits long (the Model 1 only used 16 bits of this register) but the CD4034 has only an eight bit shift register.

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