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Need a solution for a sensitive sound sensor

Discussion in 'Sensors and Actuators' started by apewrangler, Nov 1, 2017.

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  1. apewrangler

    apewrangler

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    0
    Nov 1, 2017
    Hello! I am new to the board and I come here humbly seeking the advice of some electronics experts. I have run into a bit of a wall with a project I have been working on.

    I live in an area where we can't see very far in either direction at the end of my driveway, and people on the main road tend to drive too fast. It creates a dangerous situation where it's not real safe to pull out into the road in the daylight. I considered several solutions, but when I thought about the fact that we can more easily hear a car coming before we can see it, I figured I was try to use that as a basis for a project.

    I created a display with LED level indicators to be placed at the end of the driveway near the driver's window. They would be connected to sound sensors that would be mounted approximately 100 ft each direction up the main road (so our car's engine noise would not interfere and be closer to the source). The goal was for the sensors to pic up the the sound of an approaching car and show it on the level indicators before we could actually see it zooming around the corner. I completed the assembly, but it's not working like I want. The concept works great, but the sound sensors are nowhere near sensitive enough. You have to be within an inch of the sensor for it to pick up anything on the level indicator.

    Can anyone suggest a solution that could pick up the sound of an approaching car from 200 ft away? I plan on powering this with a 12V battery.

    I attached pics of my indicators and sensors. It's just cheap stuff off ebay, but I had to start with something. Thanks in advance.
     

    Attached Files:

  2. ChosunOne

    ChosunOne

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    Jun 20, 2010
    Sound sensors pick up:
    Wind (not really wind--you can't see or hear wind, but you see and hear all the leaves and stuff it rustles)
    Rain falling on whatever's around (trees? shrubbery?) the sound sensor.
    I 'spect the sound sensor doesn't have the filter to distinguish between wind, rain and wheels-on-road noise, especially from 200' away.
    Also--be warned that if you mount these devices on trees or posts, birds WILL perch and shuffle on them from time to time. Speaking from experience.

    The usual approach to your problem is to place convex mirrors opposite your driveway. Is that an option for you, even if it means beseeching a neighbor?
     
  3. Audioguru

    Audioguru

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    Sep 24, 2016
    You provided no specifications or schematics of the cheap circuits you bought.
    All cars produce noise from their tires but the noise is almost the same as leaves rustling or rain so filters will not work. It would be easy to increase sensitivity if the schematics and parts layouts are shown.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    What about a mirror so you can see around corners?
     
  5. kellys_eye

    kellys_eye

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    Jun 25, 2010
    Is there enough line-of-sight distance to get a doppler signal? From a height even?

    Here in the UK there are rules to follow re vehicle entry/exit to roads that include safe distance (visibility) and changes to the local speed limit if visibility is limited or reduced.

    Is there anywhere to position an LED sign warning oncoming traffic of your movement into the road i.e. push a button to flash a warning for 15 seconds as you leave the property?
     
  6. 73's de Edd

    73's de Edd

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    Aug 21, 2015
    Back in and end up parking so that you can then pull out forward facing and then be able to leave in a forward direction.
    I once lived where the traffic was so continual from both directions, that this was THE solution

    That affords a close and forward view of any traffic and also the capability to get on the road very quickly with
    one quick move forward, at that permissible gap in traffic.
    Or, at the very worst times, when traffic was bumper to bumper I would wave my arm and point, and a person would usually stop traffic flow and permit me to cut in front of him for a quick right turn entry.
    Coming home at the evening , automatically left me the time to back in . . .which became FASSSST and easy with experience.
     
  7. Bluejets

    Bluejets

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    Oct 5, 2014
    Plenty of cheap and reasonable quality FPV gear on Ebay and the like.
    (Miniature cameras and radio transmitters used on quad copters etc)

    Might seem a massive task to begin with but there are plenty of examples on youtube where most is explained.

    This is just an example....
    Note that this is an older video and newer/cheaper gear is around now.

    Also it is possible with the right gear to transmit/receive audio as well as video.

     
  8. Audioguru

    Audioguru

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    Sep 24, 2016
    Don't some new cars have a "stealth" coating so that they cannot be seen? It replaces having black glass.
    No, the opposite. I saw a new car with a very shiny gold metal exterior (Beiber has chrome) and it blinds you or a camera. The sound system blasts RAP so loud that you do not know where the noise comes from.
     
  9. apewrangler

    apewrangler

    3
    0
    Nov 1, 2017
    I've attached a diagram of what I made. It's pretty basic, but it's a start.

    We already pull forward out of the drive, and it's still dangerous. There are a lot of dumb rednecks in the area who drive too fast and like throw their bud light bottles out in my yard. This is the main reason I didn't go with mirrors. They would just serve as target practice. Plus one would have to be on someone else's property. That's a negative for any line of sight solutions (cameras, motion sensors, etc.). My solution would allow me to keep everything on my property and would be basically invisible.

    I'll have to look into the FPV.
     

    Attached Files:

  10. kellys_eye

    kellys_eye

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    Jun 25, 2010
    Looks like you'll have to follow the redneck way and lob a grenade left and right before exiting......
     
  11. Audioguru

    Audioguru

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    Sep 24, 2016
    The photos of your mic and VU-meter boards show no specifications and no schematics so we do not have a clue about sensitivity and how to increase it. Please post links to their datasheets or to the seller's ad.
     
  12. Audioguru

    Audioguru

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    637
    Sep 24, 2016
    The Chinese products have horrible Engrish translations. They are very cheeeeep.
    The VU meter has no audio specifications.
    The microphone sensor also has no audio specifications but uses an LM393 dual comparator instead of amplifying the very low level mic signal with a transistor or opamp before comparing its level to a reference. If you try to set it for high sensitivity then the comparator will also probably be sensitive to supply voltage and temperature changes.
     
  13. ChosunOne

    ChosunOne

    358
    90
    Jun 20, 2010
    For a Scot, you seem to know a lot about us on this side of the pond....:D
     
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