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Recent content by StephenVB

  1. StephenVB

    mechanical turn signal blinker.

    I looked at the web site listed and it didn't have a detailed explanation. It showed one yheater and bi-metal strip and w2ouldn't work as I expect. I'm fairly sure the lamps are on as soon as power is supplied, not after the strip heats up. My observation is that the blinker on AND off times...
  2. StephenVB

    Cost effective PLCs w/ remote I/O

    I have good luck using Automation Direct PLCs - they have a large selection and many of their PLCs (Koyo) have been sold under other names: GE, TI, etc. Their prices are very good and they have a number of inexpensive options for remote I/O. In one job we used a number of 405 PLC racks with...
  3. StephenVB

    Sorting conveyor

    At this point some encoders are almost as cheap as a prox. The cost can be in the mounting. If you can find a good location for flag you can save bunches over the machining to attach to a shaft, align and mount an encoder. One thing to consider is what to do if things get out of sequence. I...
  4. StephenVB

    Touch technology inside shower cubicle?

    Atmel and a few other chip manufacturers make ICs for capacitive touch sensors that will operate through a half inch of glass (glass works better than plastic). The touch panel has to be bonded to the glass. I'm in the middle of designing an 8 key touch panel using an AT42QT1110. Atmel has proto...
  5. StephenVB

    mechanical turn signal blinker.

    I'm curious about how a (not so) simple electro-mechanical turn signal auto blinker works. The simple and incorrect answer, given by the how does it work sites, is a heater on a bi-metallic strip. This doesn't explain the blinker properties. The blinker is in series with the load. A simple...
  6. StephenVB

    Trying to Learn PLC Programming

    I been thinking about my previous post and have some other things to rant about: Independent and dependent variables. Say you have a number of different operations in a process, such as energizing a solenoid, starting a motor and lighting an indicator. If you turn these on in each place where...
  7. StephenVB

    Trying to Learn PLC Programming

    Don't get me started. I was trained as a computer programmer, assembler, C, PL1, PLM, Pascal, Cobol (the worst) ... and I believe in structured programming even with ladder where you create any structure on your own. I have been writing ladder for decades but consider my previous training...
  8. StephenVB

    PLC backplane protocols

    I have tried some and in my experience all the PLC manufacturers are very stingy with their backplane information. If you're not a BIG user and you aren't willing to spend LOTS of time at it you probably won't get anywhere. You might have better luck trying to work with a standard interface...
  9. StephenVB

    Trying to Learn PLC Programming

    My experience has been mostly in the West but I've heard that there are application and regional differences. I heard that the Auto industry does not favor AB so in the midwest AB is not that common. I also heard that NC sheet metal machines and the like have different PLCs and software, so AB...
  10. StephenVB

    2 Analogue inputs in series with one loop instrument.

    your analog device and power supply operates with a specific range of input loads. If you connect two inputs in series you may exceed this range. As previously noted each input has a resistance and the input module measures the voltage across the resistance to get the input value. With two...
  11. StephenVB

    Legal Question

    One issue I see is the difference between what they can do and what they can legally do. If you would have to pay a lawyer more to fight them than you could ever get back there's no point in fighting it. Even if you get a lawyer and think you have a solid case you could still lose. And if you do...
  12. StephenVB

    Trying to Learn PLC Programming

    PLCs programs are basically the same at a simple level, but even then they can have significant differences, such as how one-shots or state machines are implemented. As you get more complex, some allow you to mix other programming languages and other things that are very machine specific...
  13. StephenVB

    LED lifetime and output degredation with over current.

    Isn't that the way of it. I am a lowly consultant, designing boards for myself and my curstomer. If I or they ever became large customers, it would be too late to matter.
  14. StephenVB

    Shottky versus rectifier diode

    The response time of a diodes can be critical. I once accidently (it was in the wrong drawer) used a 1N4004 in a switching power supply and it's response was so slow that it might as well have been a wire. The data sheet I have on a 1N400* says nothing about response time but it's slow, OK for...

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