Sound generator/insect research.

[zotdoc]

I'm doing some research with insects specifically involving the effects of certain frequencies on their behavior. I would like to make a circuit that I can adjust the frequency of sound from very low frequency to very high frequency ultrasound. Can anyone help with circuits or equipment recomendations as well as the types of speakers or transducers I would need. I have limited funds (no bigf govt grants here!) and so will be looking at equipment on Ebay or making some of my own. Thanks for all your help in advance.

[Chris Smith]

The 555 and a piezo will do the trick.

There are tons of diagrams out there.

The HZ range is once every 400 hours to well over 100k.

Wide range, price range about a dime, and very reliable.

[Tommy volts]

zotdoc

I built this function generator: http://www.electronickits.com/kit/compl ... fg500k.htm

It will give you the frequency range you are looking for, is very easy to build, very high quality, very easy to use.

The only problem I have (and this is for all of the low frequency circuits I have built and experimented with) is that at low frequencies (say below 100 Hz) the speaker rumbles like a low revving Harley Davidson motor cycle. I have run my signal thru subwoofer amplifiers and 800 watt subwoofer speakers and about every other kind of combination and still cant get a clean low bass sin wave audio signal. I have even built speaker enclosures and other experiments trying to get the low bass (Iv’e been trying for years to reproduce the low bass sound ( 30 Hz) that teenagers get on their car stereo systems).

[Robert Reed]

Definately need to know:
What frequency range are you aiming for (should be over 15 Khz or you will drive your self away as well as insects)?

What power level do you want?

Mobile or portable?

[Tommy volts]

Robert,

The function generator I recommended to zotdoc has a range from 1 Hz to 1MHz. That should be plenty.

The human ear can detect sound frequencies ranging from a few Hertz up to about 20 KHz (although I lost the upper half of that when I served in combat contigency company Alpha 1st Tank Battalion 1st Marine Division many years ago).

I think zotdoc is all set now except for trying to solve producing low frequency audio.

I was quite surprised several years ago when I learned that no one on this forum had ever achieved designing an electronic circuit and system to produce low frequency sound on a speaker (It's easy to get 40 Hz on a piano, just bang on the far left key). Getting low frequency sound to produce on a speaker seems to be the proprietary secret of modern car stereo system designers, you hear it all the time on car stereos playing rap & hip hop.

[Chris Smith]

Humans can hear up to the 24k and to 27 k range for some, where as insects are usually in the ultrasonics.

Having a simple function generator like the 555 can do it all.

Ultrasonics like the type used in medicine is way past what is commonly used.

[Robert Reed]

Tommy
The 555 is fine for producing a range of frequencys,but it has no power-the second part of my querie. Just because airborne pests are tiny has no relation on the level of sound they will find annoying.
Tommy & Chris
The normal range of human hearing is always stereotypically stated at 20 hz to 20 khz. This takes in a wide variety of persons under a wide variety of conditions. Heres an interesting test any body can run on someone elses hearing of hi-freq. - with an audio oscillator driving a wide range speaker at moderate levels, maybe 60 db of SPL , start increasing the frequency slowly from 1000 Hz to the point where the subject says they no longer hear sound.Call this point A. Then repeat the test, only this time start at 30 khz and slowly work down until the subject says they detect sound - call this point B. Almost always point A will be at a higher frequency than point B . I suspect the reason for this is that in the first test the subject is still imagining they are hearing higher frequencies when they really aren't. I doubt if many people can detect frequencies much above 15 Khz unless some one tells them its there and to really concentratre on it.

[Chris Smith]

Robert, any simple amp using the transistor or the FET can boost the 555.

Having done many medical standards, and even using the sound oscillator with ear pieces, I have found the average person can be well past the usual 20k.

When I was young and my lower hearing was wiped out by the industry, I found my cut off frequency to be around the 27+ k, meaning that there are severl classes of people.

Usual, slightly above, and like my self being abnormal.

I lost my lower hearing early on and so I can only surmise that my upper hearing was allowed to continue on, unabated from the lower frequencies?

My sight has been the same, color deficient as normal, excellent in the other ranges of UV and IR?

What I learned many years ago is we see and hear what most disagree with, but when these frequencies are disturbed or lost, we take over and can see and hear what others are "disturbed in" because they are polluted by the norm?

UV and IR, as well as ultra sound become the norm. Every thing I have read has supported this theory.

[jwax]

For small and large ultrasonic generators, kit or built, see:
http://www.amazing1.com/
I built one of their medium power devices, and it will disperse a crown of youngins with good hearing in the high frequencies range.
It has a noticeable effect on birds and other animals too!