i did exactly the same thing and experienced the situation you're
seeing. the problem is that the 4024 triggers on the falling edge
(yuck) rather than the rising edge, so the incoming clock has to be
inverted before going to the chip, and since you took your feed off
the 4024, you're seeing the inverted clock. hence the LED will be lit
all the time, blinking off briefly when the clock happens.
my "fix", rightly or wrongly, was to take the clock from after the
15k resistor before it goes into the comparator opamp. worked for me,
though the LED isn't that bright...
hth
j
Jase is doing the AIDS ride next year - to sponsor him visit
http://www.aidslifecycle.org/1674
seeing. the problem is that the 4024 triggers on the falling edge
(yuck) rather than the rising edge, so the incoming clock has to be
inverted before going to the chip, and since you took your feed off
the 4024, you're seeing the inverted clock. hence the LED will be lit
all the time, blinking off briefly when the clock happens.
my "fix", rightly or wrongly, was to take the clock from after the
15k resistor before it goes into the comparator opamp. worked for me,
though the LED isn't that bright...
hth
j
>hi,--
>
>I've build an ASR with an LED linked to the clock input... at the
>moment it simply lights up relative to the voltage presented to this
>input. What I'd really like would be if it flashed quickly whenever
>the shift register actually changed state - if I attached the CGS LED
>driver to pin 1 of the ASR's 4024 might I be able to achieve this
>effect? Or would I need some extra circuitry?
>
>Thanks,
>t
>
Jase is doing the AIDS ride next year - to sponsor him visit
http://www.aidslifecycle.org/1674