extending the 1/4 GHz counter

extending the "A GHz counter elektor february 1980 — 2-41 A few readers have suggested extension circuits for the 1/4 GHz counter (Elektor, June 1978). The two extensions described here — leading-zero blanking and period measurement — are independent circuits. This means that either or both can be added, as required. leading-zero blanking (H.J. Busch) This little extension circuit suppresses unnecessary (leading) zeroes in the display. It has one minor disadvantage: the decimal point is not recognised as such. This means that a display of, say, 00.0123 will be converted to 123. This is no real problem, in practice, since it will not happen if the correct range is selected. The circuit (figure 1) operates as follows. In the original circuit the digits are scanned in succession, from left to right. When the last digit is displayed, the corresponding "digit strobe" pulse clears flip-flop F FA. Transistor TA is turned off, so that the first five displays are blanked. During the ...