8-Bit Ripple Counter

Cascade eight toggle stages to divide a clock by 256 and display a complete binary count.

Circuit operation

Eight falling-edge JK toggle stages form a ripple chain. The layout groups the first and second four-bit nibbles into two rows. Q0 is the least-significant output and Q7 the most-significant.

Expected behavior

$$f_{Q_7}=\frac{f_{clk}}{256}$$ $$N=\sum_{i=0}^{7}2^iQ_i$$

The 260 ms baseline includes a full 256-count cycle at a 1 kHz clock. Each successive trace has half the previous frequency. At the slower experimental clock the same saved time window intentionally shows only part of the full cycle.

Reading the results

The first voltage probe is green and the second is red. Additional voltage traces use distinct colors. Current probes, when present, start with blue and then purple. The chart opens with separate traces on a fixed time window; the table retains the same probe order. Zoom to extents includes the complete schematic.

The saved transient runs for 260.0 ms with a maximum step of 10.00 µs. Compare settled cycles after startup and use time-axis cursors to measure delays or periods.

Try a change

Set V1 period to 2 ms and pulse width to 998 µs. State changes follow the slower clock while the logic relationship remains the same. Restore the saved values after comparing the result.

Model limits

Logic gates use ideal threshold models; storage elements include finite propagation delay. Unless a transistor or LED is explicitly drawn, internal supplies, input loading, output-current limits, and metastability are abstracted. Device mismatch, temperature drift, layout parasitics, breakdown and detailed noise are not represented. The schematic and component properties expose the values used.