Discussion in 'The Projects Forum' started by dannyoh84, Jun 6, 2006.

  1. dannyoh84

    Thread Starter New Member

    Jun 6, 2006
    i am a student working on ultrasonic mosquito repeller project.

    there are 2 theories about frequencies to repel mosquitoes. One is to mimic the frequency of male mosquitoes made(11-12khz) and one was to mimic the frequency that bats made(36-38khz).

    Most product on the market is using the one around 10khz.

    i was wondering whether i should amplifier the output power to increased the signal strength since the output power from the 555 timer is very very low.what type of amplier should i use and whether it could cause disturbance to human ear since human audible is within the limit of 20khz.
    and also what type of transmitter and also a receiver to be used is suitable(is it difrent for difrent power?)? receiver is to detected the signal and to be observed on oscilloscope....thanks
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    When my cousin was in college, he spent a couple of summers counting mosquitos. Back then they were relying on nasty chemicals to keep the bugs away. I think your idea is much better.

    Here is a good link for learning how to build a class B audio amplifier:

    I'm not sure what is meant by "cause disturbance to human ear." As long as the volume doesn't get up to 90 dB(A), there should be no ear damage. (Unless someone has to listen to it all the time. 90dB(A) is "too much" for 8 hour exposure.) I suspect that the gizmo would repel humans at 45 or 50 dB(A). Under 10dB(A) it won't be noticed by most people.
  3. hgmjr


    Jan 28, 2005
    It may be of no great consequence but keep in mind that a 10KHz square-wave such as would be produced by a 555 timer will contain harmonics in addition to the 10KHz fundamental frequency.

    I don't know what impact these harmonics will have on the misquito but you may need to consider using a sinewave oscillator instead of a squarewave oscillator. I suspect that the sound emitted by the male misquito is more nearly sinusoidal in its waveshape.