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Thread: [resolved] timed relay.... keeping voltage when origional connection broken....

  1. #21
    Raw Wave
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    I still haven't reviewed what you want or need, but forget "signal" diodes (IN4148 etc).
    You need the IN4004 or 1N5404 (1A & 3A respectively) for carrying current.

    A 30A relay is usually specified as over 100,000 operations.

    Not sure what you mean by not burning coil wiring.... The relay coils won't burn with 12V.... but as I wrote, I need to re-read the lot.

  2. #22
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    Quote Originally Posted by OldSpark View Post
    Not sure what you mean by not burning coil wiring....
    sorry, a lot of what i write is babbling lol. i mean, i now understand the diode is to stop the current going the wrong way round the track, ie: forcing a one way system, so as not to overload a certain wire set [ie: dont want to have an amp powering off ig harness etc]

    and in my case, the diode is to stop the siren circuit completing via the ground jump back of the relay when the door opens, and the starter killer wire is not grounded.

    ordered a few 1a diodes [guy selling the signal diodes listed a lot of 50 for a cpl quid also.]
    max current flow should only be 500mA -> 300 the siren, and up to 200 for a second relay for later additions so 1a should suffice.

    ALSO: found the spec/datasheet for the scr and it worked. until i broke the tiny legs off the thing when removing tempory test circuit to solder into properly [just my luck - lol] - will teach me to be either more careful, or solder wires to the legs to test with next time :P lol

  3. #23
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    Quote Originally Posted by wayneox
    sorry, a lot of what i write is babbling lol
    Hey DUDE - don't even TRY competing with me! (lol !!)

    Thanks Wayne - the burning is now clarified.
    And you have shown your correct & learned thinking....

    I think too that you may understand where, if I need to buy something, I'll buy extra. At least when it's cheap and is electronic... (Murphy's Law - I will drop or misplace it; it will be wrongly connected; it will be the 12-sigma reject; ...)

    Now if only I could go back over this thread. After breakfast.....

  4. #24
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    ok just to inform...

    final diagram appears to work a treat.

    a single relay

    pin 85: hot positive...
    pin 86: ground connection - door circuit [and any single pulse grounding system, such as radar sensor, or shock sensor -> possible later additions]
    pin 30: siren ground [ also ground connection of any other part of alarm system - ie: cell call ]
    pin 87: ground via starter killer wire [with added push switch/toggle switch in the mix]
    [if 5pin - pin 87a: blank]

    diode connecting pin 86 to pin 30, direction of current being from 86-30]

    just wanted to let u guys no that this works a treat, with a 1a diode.

    when i actually wire this kit into car i will post a vid on it.

  5. #25
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    just read back on thread at top and saw:
    Quote Originally Posted by OldSpark View Post
    BTW - starter & ignition kill circuits on older cars (without LANs etc) are easy to defeat.
    i have a new car to my old astra, the starter killer will just backup the immobiliser system that is in there

    Quote Originally Posted by OldSpark View Post
    It's much better earthing the ignition coil- to ground, or better still the ignition sensor outputs (ie, reluctor, hall, optic etc) - though these require different strategies if not "open collector" outputs - ie, like points: they are either grounded else floating.
    dont fancy CAUSING shorts - mite end up inadvertantly blowing the ecu, or blowing an airbag or two?

    Quote Originally Posted by OldSpark View Post
    A broken power circuit (like starter & ignition) is VERY easy to defeat.
    A shorted system is not so easy - especially if the connections are hidden.
    true, but it will add an extra bit of time for them to actually rob the car.

    Quote Originally Posted by OldSpark View Post
    (The last ignition inhibit system I saw, the installer was stupid enough to make the break at the coil+ terminal. Now that's really dumb!)
    ok fair enough, i see this point, at least cable tie/wrap the wiring when done into the loom so its not obvious where a cut n join is made.

    this system is mainly just as stated: an alarm. my car is 9/10 parked up say 500 yrds from me, except when shopping/movies/etc
    i would just hate for someone to smash my car window, pop the door open, get in n start removing the stereo etc. -stereo needs the facia removing to remove it because of brackets behind facia. only way of doing that is sitting in either passenger or drivers seat.- which im sure most ppl would accomplish via the door -> alarm siren if only for a minute it will get my attention -> and if it doesnt get my attention im not around, so which is why i would add cell call at a later point.
    - car is only worth a couple of grand, so im not worried of it being robbed, and i know about the whole, **** em off, get a damaged car, so a plain alarm will do - no razors/shocks etc, would rather loose the stereo equipment n repair a window then repair every panel on the car because i slashed the guys hand up n he got ****ed off. - although blood may be good for tracing who stole it, but cops here DGARA for plain car break ins - even when my old housemates car was broke into, blood was on door handle, etc, she said they didnt wanna take samples, and she was a coppa so...

    n e how, once again its well past midnight, so im off to bed. nite

  6. #26
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    Quote Originally Posted by wayneox
    dont fancy CAUSING shorts - mite end up inadvertantly blowing the ecu, or blowing an airbag or two?
    Nope - you are shorting ground to ground. This is the coil's grounding circuit to the points or ignitor - it's as if the points never open, hence the coil never fires. And being open-collector circuits, you won't blow them by "shorting" to ground.
    To defeat it, you have to disconnect both the dizzy/ignitor AND the coil- and run a separate wire to connect them.
    Now that WILL cause delays!


    Re "A broken power circuit (like starter & ignition) is VERY easy to defeat"...
    Quote Originally Posted by wayneox
    true, but it will add an extra bit of time for them to actually rob the car
    No it won't. At least IMO - it's the time to open the bonnet plus about 5 seconds (if that) to circumvent. It is so easy.


    As to the "visible" break in the coil+ wiring, that will make no difference to most thieves - they just bypass it anyhow (and then manually trigger the starter motor).
    But for thieves that have no clue, it may provide the hint required to power the ignition.


    I'm just pointing out that immobilisers that prevent power to the ignition circuit (ie, coil or ignitor) and inhibit the starter are EASY to defeat - it almost takes longer to defeat the steering lock(s).
    If your immobiliser doesn't work by merely preventing power to the ignition circuit (ie, coil or ignitor), then you may have a reasonable system.

    BTW - I presume you mean "steal" the car. None of this does anything to prevent robbing the car.

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