1Hz Timebase For Readout And Counter Applications
This counter makes direct readout of frequency-generating equipment very easy when a 1-H
z time-base is added to latch, reset, and the count signal is conditioned. This design has the flexibility to select either polarity. By differentiating, inverting, and ORing the clock pulses in XOR gate U2A, a stream of 1-Hz, positive, 200-/as pulses is generated. For latching, the 1-Hz stream is again differentiated in U2B, input 1 to supply a 50-/as pulse. Though U2B"s output goes from high to low, it can be reversed, by making input 2 low. Because the reset pulse must occur after the latch signal, the 1-Hz stream from U2A is delayed 100 at U2C input 1. The output-pulse polarity is determined by making U2C"s input 2 either high or low.