Similar to the count has reached binary 1111, the then pulse sends the O4 output of IC3 high, which disables IC2c and IC3 stops together with. The four used outputs of IC3 are connected to a resistor ‘ladder’ which acts because a undemanding digital to analog convert-er (DAC). As the count increases so does the voltage produced by the top of the ladder and this is connected to the inverting inputs of four comparators inside IC4 (an LM339) and to IC5, which is a 741 op amp besides connected for instance a comparator.
The certain inputs of the comparators are connected to the taps of a voltage barrier, with the drumming voltages frozen using VR1, a 100kO trimpot. As IC3 counts, the rising stepped voltage from the DAC ladder switches the comparators on during sequence, preparatory with IC4d and working up to IC5. because each one comparator is bowed on, its put together of LEDs is lit; essential LEDs 1 & 2, so therefore LEDs 3 & 4 and so on. at what time all five pairs of LEDs are lit, the after that pulse from IC1 moves the binary count of IC3 to 10000, so the DAC voltage drops back to zip and all LEDs are extinguished. by the same age, plus additionally stops, as the lofty on O4 causes IC2c to mass expand gate pulses. The circuit it follows that remains stationary until the counter is reset by burning pushbutton switch S1. This allows a new-fangled sequence to kick off.