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Groups > sci.electronics.design > #453935

Re: Ignition circuit issue.

From Sylvia Else <sylvia@not.at.this.address>
Newsgroups sci.electronics.design
Subject Re: Ignition circuit issue.
Date 2017-03-28 11:13 +1100
Message-ID <ejto4gFgbh6U1@mid.individual.net> (permalink)
References <ejoupmFhi4bU3@mid.individual.net> <dljedc94rmsgrh4gvv5ettk1tc26i4kivv@4ax.com> <ejp5l5FinsjU1@mid.individual.net> <97e92e25-4f48-4f6d-b18f-8b34df839ab7@googlegroups.com>

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On 28/03/2017 1:16 AM, dagmargoodboat@yahoo.com wrote:
> On Sunday, March 26, 2017 at 2:33:13 AM UTC-4, Sylvia Else wrote:
>
>> Finally got the engine running today, using this ignition circuit, and
>> LPG, after many hours spent cursing a PIC32MX that I was temporarily
>> using to generate the trigger pulse - got caught out by yet another PIC
>> errata - input capture doesn't work when the processor is in the idle state.
>>
>> Sylvia.
>
> Was that PIC quirk the problem?  Otherwise, I'd ask
> o  Whether C4 might be bad, open, or the wrong value?

No, and I even replaced it. Its value is far from critical anyway.
>
> Or, that not being the case, maybe the LT1243's upset about having its
> FB pin pulled all the way to +5v (wind-up?)?

It's within spec. Another possibility is that the LT1243 is interpreting 
the sudden drop in FB as an indicator of an output short, but if so, I'd 
expect it to object to every such occurrence, not just the first.

>
> Is the LT1243's Vref getting glitched from your reset circuit, upsetting
> the LT?
>
> Just some wild ideas.  From your description it really sounds like it's
> RT/CT pin-related, and you've already put your finger on it (so to speak :).

The IC is not really designed with this application in mind. Perhaps it 
just plain doesn't like being used this way.

Sylvia.

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Thread

Ignition circuit issue. Sylvia Else <sylvia@not.at.this.address> - 2017-03-26 15:36 +1100
  Re: Ignition circuit issue. John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-25 22:33 -0700
    Re: Ignition circuit issue. Sylvia Else <sylvia@not.at.this.address> - 2017-03-26 17:33 +1100
      Re: Ignition circuit issue. Larry Sheldon <lfsheldon@gmail.com> - 2017-03-27 00:54 -0500
        Re: Ignition circuit issue. Sylvia Else <sylvia@not.at.this.address> - 2017-03-27 19:34 +1100
      Re: Ignition circuit issue. dagmargoodboat@yahoo.com - 2017-03-27 07:16 -0700
        Re: Ignition circuit issue. makolber@yahoo.com - 2017-03-27 09:18 -0700
        Re: Ignition circuit issue. Sylvia Else <sylvia@not.at.this.address> - 2017-03-28 11:13 +1100
  Re: Ignition circuit issue. Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-03-27 16:25 -0700
    Re: Ignition circuit issue. Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-03-27 16:31 -0700
      Re: Ignition circuit issue. Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-03-27 16:36 -0700
      Re: Ignition circuit issue. Sylvia Else <sylvia@not.at.this.address> - 2017-03-28 15:19 +1100
        Re: Ignition circuit issue. Neon John <no@never.com> - 2017-03-31 14:41 -0400
          Re: Ignition circuit issue. Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-03-31 11:55 -0700
    Re: Ignition circuit issue. Sylvia Else <sylvia@not.at.this.address> - 2017-03-28 12:03 +1100
      Re: Ignition circuit issue. piglet <erichpwagner@hotmail.com> - 2017-03-28 08:39 +0100
        Re: Ignition circuit issue. Sylvia Else <sylvia@not.at.this.address> - 2017-03-28 20:54 +1100

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