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HT interference via Stamp — Parallax Forums

HT interference via Stamp

ArchiverArchiver Posts: 46,084
edited 2003-06-10 12:31 in General Discussion
hello group and many thanks in advance...

I am running two Basic Stamps (networked) and have them controlling a
variety of applications for an installation. One of the pins is controlling
a spark generator (like the kind you would have in a domestic electric
boiler)...The code seems fine, problem is that as the spark is generated by
HT (high tension) i.e a massive release from a capacitor, making a spark
between an electrode and the nearest piece of grounded metal. This HT spark
is strange as it causes the Stamp to Reset each time...

i have tried to completely isolate this system too in an effort to avoid
electrical feedback into the stamp/breadboard etc. Currently the stamp and
the outputs are running entirely seperately from the spark generator ( they
share a common electrical mains ring only)...It may be an electrical spike
jumping through the insulation on a wire but i'm not sure...I tried building
a Faraday cage around the stamp and associated circuits etc to no avail...I
built a switch to control the spark generator pressed open/closed by a
solenoid driven by Stamp...it was all insulated and no electrical feedback
should have occured, although it did, again Reset...
I then used a manual switch and still it reset the stamp..There is
definately no physical (i.e. via wire or metal) conection between the spark
and the stamp and I am comp[noparse][[/noparse]letely puzzled as to the relationship between a
spark generator and the stamp..
i hope you will have had some experience of this problem with stamp and HT
before...
Any advice would be greatly appreciated,
Kind regards,
Jon Thompson

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Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-06-10 00:48
    Did you try it with the ATN pin grounded? That is one sensitive
    point on the Stamp, vis a vis an electromagnetic pulse propagating
    away from the spark generator.

    The Faraday cage should stop that, but if it is truly a big spark, it
    may take a lot of shielding. It is possible for the EM disturbance
    to be coupled in through the wiring to the mains or through the
    network cable between the two stamps, or any other wire that
    penetrates the shield. Cables should be shielded and should pass
    through ferrite bead noise suppressors. (Wrap the entire wire,
    shield and all, around or through a bead)

    How about a single BASIC Stamp, powered by a 9 volt battery, with
    only an LED or buzzer to indicate occurrence of a reset, inside the
    Faraday cage, Does that reset? If so, more shielding.

    hmmm

    -- Tracy



    >hello group and many thanks in advance...
    >
    >I am running two Basic Stamps (networked) and have them controlling a
    >variety of applications for an installation. One of the pins is controlling
    >a spark generator (like the kind you would have in a domestic electric
    >boiler)...The code seems fine, problem is that as the spark is generated by
    >HT (high tension) i.e a massive release from a capacitor, making a spark
    >between an electrode and the nearest piece of grounded metal. This HT spark
    >is strange as it causes the Stamp to Reset each time...
    >
    >i have tried to completely isolate this system too in an effort to avoid
    >electrical feedback into the stamp/breadboard etc. Currently the stamp and
    >the outputs are running entirely seperately from the spark generator ( they
    >share a common electrical mains ring only)...It may be an electrical spike
    >jumping through the insulation on a wire but i'm not sure...I tried building
    >a Faraday cage around the stamp and associated circuits etc to no avail...I
    >built a switch to control the spark generator pressed open/closed by a
    >solenoid driven by Stamp...it was all insulated and no electrical feedback
    >should have occured, although it did, again Reset...
    >I then used a manual switch and still it reset the stamp..There is
    >definately no physical (i.e. via wire or metal) conection between the spark
    >and the stamp and I am comp[noparse][[/noparse]letely puzzled as to the relationship between a
    >spark generator and the stamp..
    >i hope you will have had some experience of this problem with stamp and HT
    >before...
    >Any advice would be greatly appreciated,
    >Kind regards,
    >Jon Thompson
    >
    >_________________________________________________________________
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  • ArchiverArchiver Posts: 46,084
    edited 2003-06-10 01:02
    It is possible for you to completely isolate using an opto isolater, so that
    the only thing common between the two circuits is the atmosphere?


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2003-06-10 03:35
    Hi Jon,
    I run stamps with Plasma Cutting Machines and they use a spark generator to
    start the sequence.

    I use opto-isolators driving a mechanical relay to fire the HV transformer. I
    also use Digital Noise Filters on every I/O pin on the stamp, and the serial
    pins (1-3).
    I am out of the office this week so I done have the part numbers handy. They
    are made by Panasonic and I get them from Digikey. they are a 3 wire device
    that has 2 caps in series and a coil to ground.
    Just found the number: Panasonic ELK-AH470GB Digikey P9854-ND They are
    around $.75 each.
    I also put a .1 uf cap at the +5 into the stamp, use a local power supply
    (120 ac with a transformer and regulated to +5 on the PC Board.
    With this setup I have not had a single reset problem. I have about 20 of
    these systems running for the past 4 years. (Now that I have shot off my mouth
    I'll get 20 calls tomorrow with this problem!!!)

    Thanks,
    Alan Bradford
    Plasma Technologies
    www.plasmatechnologies.com


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2003-06-10 12:31
    many many thanks for the advice from those of you who replied to the HT
    issue..

    I'll try out some of those potential solutions and let you know how i got
    on..

    Again, it's good to know that there are others out there who can help...

    Kind Regards,
    Jon Thgompson


    >From: plasmastamp@a...
    >Reply-To: basicstamps@yahoogroups.com
    >To: basicstamps@yahoogroups.com
    >Subject: Re: [noparse][[/noparse]basicstamps] HT interference via Stamp
    >Date: Mon, 9 Jun 2003 22:35:31 EDT
    >
    >Hi Jon,
    >I run stamps with Plasma Cutting Machines and they use a spark generator to
    >start the sequence.
    >
    >I use opto-isolators driving a mechanical relay to fire the HV transformer.
    >I
    >also use Digital Noise Filters on every I/O pin on the stamp, and the
    >serial
    >pins (1-3).
    >I am out of the office this week so I done have the part numbers handy.
    >They
    >are made by Panasonic and I get them from Digikey. they are a 3 wire device
    >that has 2 caps in series and a coil to ground.
    >Just found the number: Panasonic ELK-AH470GB Digikey P9854-ND They are
    >around $.75 each.
    >I also put a .1 uf cap at the +5 into the stamp, use a local power supply
    >(120 ac with a transformer and regulated to +5 on the PC Board.
    >With this setup I have not had a single reset problem. I have about 20 of
    >these systems running for the past 4 years. (Now that I have shot off my
    >mouth
    >I'll get 20 calls tomorrow with this problem!!!)
    >
    >Thanks,
    >Alan Bradford
    >Plasma Technologies
    >www.plasmatechnologies.com
    >
    >
    >[noparse][[/noparse]Non-text portions of this message have been removed]
    >
    >
    >To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    >from the same email address that you subscribed. Text in the Subject and
    >Body of the message will be ignored.
    >
    >
    >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
    >
    >

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