Re: 4017 Counter skips under load

On Jul 4, 4:29 am, Fred Bloggs <nos...@xxxxxxxxxx> wrote:
jcargile2...@xxxxxxxxx wrote:
Sorry, I mistyped. The clock pulse coming into the 4017 from the PC
parallel port is 25 ms in length. The counter then activates the next
relay in sequence and the output stays active for 10-20 seconds before
moving on to the next firing cue. I'll post a printout of the circuit
design when I get home in a couple hours. I'm using a pretty good
sized power supply, and I've tried other power sources as well with
the same results. Should I be doing some sort of decoupling where the
power enters the board as well? I noticed that the parallel port
interface card that I'm using has some sort of diode/cap combination
where the power enters the board. Would this help even things out
further?

The printer port puts out TTL compatible voltage levels and will not
reliably clock a 4017 powered from 12V. The 4017 will have problems
driving the typical relay coil directly. You should forget about
completing this project on time and ask your teacher for an extension.
You have a lot more homework and circuit modifications to perform before
you get close to finishing it.

The thing that confuses me is that in tests that I ran last week, the
system worked fine with only a test load. The clock pulses generated
by the Kit74 advanced the 4017 one step each time with zero errors. I
used the exact equipment I am now, including the ethernet cable to
deliver the clock pulses. It wasn't until I installed it into the
firing setup and did a test with an actual igniter that these problems
began to occur. After I increased the wire gauge for the power supply
to the firing boards, it had enough power to fire the igniters, but
began skipping steps and was far more susceptable to any sort of
interference. Even checking the power supply lines with a DVOM was
enough to move the counter several steps.

.

Relevant Pages

  • Re: 4017 Counter skips under load
    ... parallel port is 25 ms in length. ... sized power supply, and I've tried other power sources as well with ... driving the typical relay coil directly. ... The clock pulses generated ...
    (sci.electronics.design)
  • Re: 4017 Counter skips under load
    ... But when I try to operate the circuit under load ... skips the loaded relay and moves right to the next output. ... Think "star grounding" and power decoupling. ... lead from the parallel port as short as possible. ...
    (sci.electronics.design)
  • Re: 4017 Counter skips under load
    ... But when I try to operate the circuit under load ... skips the loaded relay and moves right to the next output. ... Think "star grounding" and power decoupling. ... lead from the parallel port as short as possible. ...
    (sci.electronics.design)
  • Re: 4017 Counter skips under load
    ... parallel port is 25 ms in length. ... sized power supply, and I've tried other power sources as well with ... Should I be doing some sort of decoupling where the ... The 4017 will have problems driving the typical relay coil directly. ...
    (sci.electronics.design)
  • Re: simple pulse circuit?
    ... power, and will burn out. ... computer with a parallel port running, and that is a lot of effort ... little pump at 1 mL/min. ... use a low voltage wall wart. ...
    (sci.electronics.design)