High frequency 25-45kHz sound generator circuit, where to buy ready made?

[harvestmouse]

Hello All. First post here. Forgive me if it's in the wrong place. My knowledge of electronics can be written on the back of a stamp.

I have a project in mind. Need to generate sound between 25 and 45kHz. Variable DC voltage, say 3-15v (if my understanding of Piezo is correct in that if you want it louder, you give it more volts). I can sort out the power at one end and the Piezo buzzers at the other end, but I need to buy the middle bit.

Where can I get (in Europe) the required circuitry ready made? Doesn't have to be in a case, just with nothing to solder.

Thanks in advance. I can rewire a house and mig-weld cars, but you can see what's going on there, unlike electronics.

 

[rjenkinsgb]

One of these?

M048N Ultrasonic Generator

www.kemo-electronic.de

They appear to also be on Amazon, ebay etc., if you search for Kemo MO48N

 

[Tony Stewart]

It depends how powerful you need it? a few watts or 50 W Steve Gibson has a high power design for pest control.

But usually, you can run it off 12Vdc and use a stepup autotransformer coil to power it from a pulsing LM555 timer IC design and a power transistor.

The low power cheap solutions may work for you.

Amazon.com : ultrasonic pest control

Oooh scary Halloween

 

[harvestmouse]

I tried a device from Amazon; it didn't work, even at six feet away for a month. They refunded me ok, but that was my incentive to build one myself.

In answer to the previous post, as powerful as possible. Am researching how to direct piezo sound (High Frequency doesn't travel far apparently) and any help about directing sound would also be appreciated. Is it really as simple as putting the Piezo buzzers in tubes?

The MO48N does seem to do what I asked about in the first place, but it has mixed reviews, as do most devices.

It seems that the missing attributes are directionability (is that a word?) and volume.

 

[Nigel Goodwin]

I tried a device from Amazon; it didn't work, even at six feet away for a month. They refunded me ok, but that was my incentive to build one myself.

In answer to the previous post, as powerful as possible. Am researching how to direct piezo sound (High Frequency doesn't travel far apparently) and any help about directing sound would also be appreciated. Is it really as simple as putting the Piezo buzzers in tubes?

The MO48N does seem to do what I asked about in the first place, but it has mixed reviews, as do most devices.

It seems that the missing attributes are directionability (is that a word?) and volume.

What are you trying to do?, if it's scare some kind of creature away, there's little evidence that such devices actually work.

 

[Tony Stewart]

Not a reliable solution to threaten all pests, but here's a DIY power solution for ultrasonic.
The tone variation in modulation is important I would expect as well as the element of surprise.

Ultrasound is very directional and bounces off walls everywhere.

GRC's | The Quiet Canine - Mission Statement

The Quiet Canine - Mission Statement

www.grc.com

 

[harvestmouse]

It's back to the old dog barking issue, but I didn't want to go straight to that in the title. It seems from my limited research that HF signals are used in canine training, but the transmitter has to be near the dog, or option 2 if possible is to amplify the signal and point it in the right direction.

Ready-made devices often have small internal batteries / power cells, possibly incapable of sending the sound waves any good distance.

Mains to DC transformer could power half a dozen buzzers??

 

[harvestmouse]

Any forum from the USA on this subject tends to end up with the same (very effective) alternative, but I don't own a firearm.

Am sure it could be possible to build something that actually works. If a company is building something down to a price as opposed to up to a standard, it can't be that good.

 

[rjenkinsgb]

If you want it really directional, you either need a parabolic reflector or a phased array, something like this:

https://www.kickstarter.com/projects/richardhaberkern/soundlazer-snap-the-directional-parametric-speaker

 

[atferrari]

From what I heard better you do not try those things near newborns. They seem to suffer them a lot.

 

[harvestmouse]

Clear straight line between me and dog. No people in a 120 degree radius.

Re. "Steve Gibson has a high power design for pest control...."

50 watts would be great. Any more info?

 

[harvestmouse]

Soundlazer on noise b gone site, says "coming soon" i.e. not in stock.

Also, max range 12 metres, even for the 335€ model. Too short. Is this normal, for high frequency, or is it the directionable aspect that reduces the distance?

 

[Nigel Goodwin]

Soundlazer on noise b gone site, says "coming soon" i.e. not in stock.

Also, max range 12 metres, even for the 335€ model. Too short. Is this normal, for high frequency, or is it the directionable aspect that reduces the distance?

Both, but what makes you think it would work anyway? - there seems little evidence that it has any effect. But higher frequencies don't travel as far, and to increase range it needs to be more directional.

Directionality is a function of the transducer, and more specifically probably the horn on the transducer - assuming you can get different types?, you would need a long throw horn (matched to the specific driver).

There have been countless threads on these forums about this over the years, I don't recall anyone ever having any success?.

 

[harvestmouse]

Directionality is a function of the transducer, and more specifically probably the horn on the transducer - assuming you can get different types?, you would need a long throw horn (matched to the specific driver).

I wish I understood what that meant. Will research.

 

[Nigel Goodwin]

I wish I understood what that meant. Will research.

Long throw, and short throw (and middle throw) are terms used in PA systems - so at a HUGE gig they will have short throw speakers aimed at the front rows, middle throw speakers aimed at the middle rows, and long throw speakers for the back rows.

 

[Tony Stewart]

A parabolic dish, and horn , an optical lense and a cone are all directional so the gain is like a lens that magnifies brightness but reduces beam angle.

It's that simple.

A convex cone spreads energy and concave dish focuses energy. The shape is usually parabolic. A horn spreads in one direction more than the other in XY mode depends on the parabola curve.

Because ultrasound wavelength is so short compared to say audio or bass reflections, ultrasoind can be more focused in a small shape of the reflector.

 

[harvestmouse]

Thank you both for the explanations. It's making more sense now.

I have seen piezo square horns for sale, rated at up to 45kHz, as well as flat round versions. Which of the two shapes would be the more concave inside (I can only see the outside of the box) ?

 

[Nigel Goodwin]

Thank you both for the explanations. It's making more sense now.

I have seen piezo square horns for sale, rated at up to 45kHz, as well as flat round versions. Which of the two shapes would be the more concave inside (I can only see the outside of the box) ?

They are short throw, and were what I presumed you were already using?.

 

[harvestmouse]

Ideally I'd like the sound to have an effective range of 25 metres in an uninterrupted line. No idea about range of Piezo horn, I'd guess that I want long throw, but am obviously receptive to advice.

 

[Nigel Goodwin]

Ideally I'd like the sound to have an effective range of 25 metres in an uninterrupted line. No idea about range of Piezo horn, I'd guess that I want long throw, but am obviously receptive to advice.

Why not try what you have close up to start with - and see if it has any effect?. No point trying to extend range, when the entire premise may well be wrong.