Hi all. As part of a project I am building a 74LS90 divide by 10 counter, with a clock input from a 555 timer at 1Hz.
I have built the circuit just like the circuit diagram in the link below. The Qa input is supposed to toggle each clock cycle, but if I use a logic probe to check this it remains low; same results if I use a led. I've reproduced this on 2 differing IC's.
http://www.electronics-tutorials.ws/counter/cou29.gif
I can post a diagram/photo, however my circuit is wired just like the one in the link above, I ve taken care to ensure proper grounding for the reset pins (R1R2S1S2), with clkB connected outputs Qb Qc Qd count upwards as expected, but still nothing from Qa..
Can anyone assist?
I have built the circuit just like the circuit diagram in the link below. The Qa input is supposed to toggle each clock cycle, but if I use a logic probe to check this it remains low; same results if I use a led. I've reproduced this on 2 differing IC's.
http://www.electronics-tutorials.ws/counter/cou29.gif
I can post a diagram/photo, however my circuit is wired just like the one in the link above, I ve taken care to ensure proper grounding for the reset pins (R1R2S1S2), with clkB connected outputs Qb Qc Qd count upwards as expected, but still nothing from Qa..
Can anyone assist?