Back to repelling bats

[rogs]

As bats have the ability to reject the ultrasonic transmissions of other nearby bats, why would they also not be able to ignore the presence of of any other 'foreign' ultrasonic source?

If you use a bat detector, to record a group of bats feeding on insects, you notice there's quite cacophony going on all around. I've always been impressed at their ability to ignore local ultrasonic 'noise' from other nearby animals, and I don't think a deliberately introduced ultrasound generator will trouble them much.
Possibly if it was seriously loud ?......

 

[ronv]

Back to the job at hand. If IC1 in your layout is a micro it will need an oscillator to run.

 

[MrDEB]

usiong the 8khz internal oscillator.
I think Nigel is on to my problem of hearing the sound. Maybe the PS filter caps.

 

[gary350]

Why would anyone want to repel bats??????????

Bats eat there body weight in mosquitos and bugs every day.

I put up bat houses I want all the bats I can get!!!!!!!!

 

[chiba]

Use nets...
https://www.electro-tech-online.com/custompdfs/2011/06/Flying-fox-control-methods-research.pdf

I find it rather amusing that some of the foxes used the audio repellent devices as roosts

 

[Sceadwian]

gary360, perhaps you didn't notice from the previous posts that these are fruit bats =) The have to land to eat so they'll snack and sleep in the trees and poop all over the place.

 

[Mr RB]

Use nets...
https://www.electro-tech-online.com/custompdfs/2011/06/Flying-fox-control-methods-research-1.pdf

I find it rather amusing that some of the foxes used the audio repellent devices as roosts

That's one of the problems with ultrasonics they are directional beams. It's probably totally quiet under the sound box, as they pump the sound in beams out the sides...

Maybe you need the sound emitter away from the tree but the beam pointed at the tree?

 

[Sceadwian]

That'd work Mr RB, but even being directional you lose LARGE amounts of power over distance, especially considering damp air and materials will eat ultrasonic sound for lunch, bats on the inner branches may not even be bothered and you'd probably need 10-100 times the power at multiple points around the tree... A net is FAR cheaper far simpler and far more effective period. That's why they use them =>

 

[Mr RB]

Hmmm... What about electrified FRUIT! Works on birdies too.

 

[MrDEB]

Well the results are in. The guy I sold a unit to called and ordered 5 more units (large ranch w/ lots of bats)
this study http://www.247wildlife.com/batultrasonicsound.htm has some inconsistencies in it seeing how my unit outputs ultrasonic sound and the bats that were living under his eves and cupola went from 20+ to 1 every now and then only in the morning.
I guess you can't believe everything you read.
Thanks to all who helped in the circuit design

 

[audioguru]

Congratulations, MrDEB, it works!
Maybe your circuit picked up an acid rock radio station.

 

[MrDEB]

LOL--acid rock station
Its a good feeling when a project works and it performs to expectations.
The most expensive part is the enclosure at $15 per. Allied Electronics has a good price on them (PANTEC FLXT 7050)
I need to redo the pc board as the last one had some osscilations going on with the LM386 amp (you can barley hear the signal output but it is supposed to be ultrasonic. The first unit I buit you could not hear. The problem pcboard had traces that lifted so I had lots of repairs. I figure I got the board too hot when laminating.
I hardwired several .01 caps across the supply pins to the PIC and the LM386.
Hardwiring is not a desired method with 15-30khz signals.

 

[MrDEB]

updating of circuit amp output

Orginal circuit used an LM386 but that chip does not perform as well as was suggested (TDA2822)
I added an attenuation circuit as suggested to the LM386 and wonder if same should be done with the TDA2822?
one is the LM386 schematic while the second pic is using the TDA2822 chip.
Am sure Audio will address this. That guy amazes me in his knowledge of audio circuitry.

 

[gary350]

In the summer I run a 25 watt light bulb outside all night to attract bats, they eat their body weight in bugs every night. They eat about 3000 mosquitoes every night.

A 100 watt light bulb makes too much light and too much heat and the bats stay away.

 

[MrDEB]

This unit is programmed to scare away birds (pigeons that crap every where) thus it is battery operated 24/7
Outputs sound for 30 seconds then off two miniutes

 

[audioguru]

Hi Mr DEB,
You are not using a TDA2822 that has 16 pins, instead you are using a TDA2822M that has only 8 pins.

You are throwing away a lot of output level because you are not bridging both amplifiers for 3.5 times more output than using a single amplifier.
The circuit does not use 4.7k resistors. They are 4.7 ohms.

The amplifier has a voltage gain of almost 100 times so an input attenuator is needed. I can't remember the input signal level and I can't remember your battery voltage.

Here is the schematic from the datasheet of a bridged amplifier:

 

[MrDEB]

I googled the wrong package?
Will try again
Any input on attenuation circuit used with the LM386?
That pic you posted is the one I got the Bridge Application circuit from??
will research
battery voltage is 6 C cells = 12v but when cold weather sets in it will go down for sure.

 

[MrDEB]

The 16 pin package is obsolete

data sheet for 8pin smd https://www.electro-tech-online.com/custompdfs/2012/01/CD00000133.pdf
will search for the 16 pin but hopefully not obsolete as Mouser says it is.

 

[MrDEB]

possible substitute LM4871
**broken link removed**
battery voltage is not an issue as the pic runs on 5v anyway don't feel the H bridge amp is feasible as it is tooo loud for in town app.

 

[atferrari]

What piezo - Variations

What was the actual tweeter you used?

Could it be that bats get used to your US in the future? Happened to somebody I recall with his mother in law...

There was a design (maybe in Radioelectronics?) with random variations of frequency and on / off intervals.