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Is remote started car running?

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by AGCB, Mar 6, 2018.

  1. dknguyen

    dknguyen Well-Known Member

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    I agree with crutschow's implication. A comparator will fix that "hysteresis" problem. It's not really hysteresis but w/e.
     
  2. dr pepper

    dr pepper Well-Known Member Most Helpful Member

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    Ok non invasive no contact, nad electrically simple.
    A largeish coil on the garage floor under the engine, a high gain amp to pick up the electrical noise generated by the vehicles electrics providing a digital output.
     
  3. AGCB

    AGCB Member

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    I've used comparators but how would that work here?
     
  4. dave miyares

    Dave New Member

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  5. dknguyen

    dknguyen Well-Known Member

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    You provided no information about your sound detector, but if it is what I am imagining that it is, then put the comparator between the digital output of the sensor and the LED and resistor. In other words, have the sensor drive the comparator have the comparator drive the LED.

    That way the comparator decides when the LED turns on at any sound level and hysteresis you want, whereas before the LED would only turn on when the volume produced sufficient power to directly drive the LED.
     
  6. AGCB

    AGCB Member

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    I thought of something like that but I'm not too good with that sort of design. I don't want you to design something for me but would you point me to more info. It's the AC part of this that I have no experience with.
    Thanks
     
  7. dknguyen

    dknguyen Well-Known Member

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    Oh wait, a second you said your sound detector has a digital output. Yeah...not that won't work then. Need to be analog.
     
  8. dave miyares

    Dave New Member

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  9. dr pepper

    dr pepper Well-Known Member Most Helpful Member

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    Well I'm happy to help you, however designing & building by proxy isnt easy or a good idea, maybe stick to something your comfortable with.
    If I was to start something like this, and you are determined to have a go, and presuming you have a 'scope I'd make a coil about 2' diameter or maybe just a reel of wire and bung it under the engine & 'scope the output, if you only get a few 100uV its not a good idea, but if you get an o/p in the order of mV then an op amp and a 555 would probably do the trick.

    I googled but couldnt find anything like the above, I did find this though, maybe you could fit something like this to the vehicle and use its o/p to trigger a radio module or an infra red Led to signal to another device in the garage:
    https://www.electroschematics.com/7042/engine-running-detector-load-switch/
     
    Last edited: Mar 7, 2018
  10. crutschow

    crutschow Well-Known Member Most Helpful Member

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    Since those sound detectors you bought have a digital output, you might try buffering them with a transistor (2N3904 or similar) to drive the LED and see if that makes a difference.

    Otherwise you can send their amplified analog sound output to an external comparator, such as an LM339, and adjust its sensitivity (trigger point) to your liking. The comparator will turn on when the audio signal peaks exceed the comparator trip point.
    The LM339 output then drives the LED.
     
  11. Frozenguy

    Frozenguy Member

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    Do you use microcontrollers at all? If so, a cheap vibration sensor ($0.30) can be taped/blued/ziptied to the engine and then wired to an interrupt pin on a ($1.27) ATtiny85. ATtiny85 then makes an output high which an ESP8266 or RF module reads, then sends it to a second ESP8266 or RF on your garage windowsill, and then that shines an LED to your house. The car side of this solution is compact, fits in your hood forever, and runs off your battery without draining it.


    Avoiding microcontrollers; you can put a temperature sensor with a comparator on the garage door/wall somewhere behind the car exhaust. It doesn't have to be exact. When the car starts, temperature behind the car will significantly increase especially if it's cold outside (needing the remote start). Wire that to your LED on the window.
     
  12. camerart

    camerart Active Member

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    Hi A,
    As mentioned before 'dashboard sensor' There is a wire that goes to the igniton light, that is sometimes used for leisure battery relays. This could be used for detection.

    If you are happy with a wire that needs to be disconnected before driving, then a lead to 'as mentioned' a light on the garage or somewhere it can be seen, even in the house. Or a radio connection.
    Camerart
     
  13. AGCB

    AGCB Member

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    I have used Arduino's some and PIC's and Propeller's much.
    I like the idea of sensing exhaust temp.

    I'm still working on the sound device. Have some stuff coming today that was not in my junk drawer.

    NOT good for the wife!!!

    Thanks for all replies.
    Aaron
     

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