need a quick ultrasonic noisemaker

[Michael]

For the neighbor's dog. Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz. In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea? I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit? Should I put a cap between the +12V and
the speaker?



--------------------------[switch]-- + 12V
| |
| |
| _ /
|-- |_| 4 ohm speaker
| | \
-------- |
| 8 4 | |
| | |
| 555 | D
| 3|----47R----G IRF530 MOSFET
| | S
| 1 | |
-------- |
| |
| |
-------------------------------- GND

 

[Bob Masta]

On Mon, 14 Sep 2009 22:19:07 -0700 (PDT), Michael
<mrdarrett@gmail.com> wrote:

For the neighbor's dog. Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz. In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea? I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit? Should I put a cap between the +12V and
the speaker?



--------------------------[switch]-- + 12V
| |
| |
| _ /
|-- |_| 4 ohm speaker
| | \
-------- |
| 8 4 | |
| | |
| 555 | D
| 3|----47R----G IRF530 MOSFET
| | S
| 1 | |
-------- |
| |
| |
-------------------------------- GND

The speaker will have the final say on what
frequencies you get from this. This is a
generally bad design if you are using a
conventional (voice coil and magnet) speaker,
since it applies DC to it and tends to move its
voice coil out of the proper centered position.

But that's immaterial here, since you will have a
hard time finding a conventional speaker with much
ultrasonic output. Special tweeters are
available, but they are not cheap.

You could look into piezo tweeters, which are not
only cheap, but are usually used with a DC
blocking cap anyway... and some do go to the
ultrasonic range. The problem is getting enough
power for your purpose. (Actually, the first
problem is getting a data sheet that even mentions
the power output and has a frequency response
plot!)

You could see if there are pre-tuned piezo
oscillators for this type of use. But I think
this is going to be a lot tougher job than you
think. For one thing, how will you know how much
(if any) ultrasonic sound you are getting from
your gadget? If you thought ultrasonic speakers
were expensive, ultrasonic mics are in the $1000+
range!

Best regards,


Bob Masta

DAQARTA v4.51
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!

 

[Shaun]

"Michael" <mrdarrett@gmail.com> wrote in message
news:b5bf2180-7aa0-4ae3-b864-b7d5b9e2465f@z3g2000prd.googlegroups.com...
On Sep 15, 5:59 am, N0S...@daqarta.com (Bob Masta) wrote:

On Mon, 14 Sep 2009 22:19:07 -0700 (PDT), Michael



mrdarr...@gmail.com> wrote:
For the neighbor's dog. Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz. In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea? I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit? Should I put a cap between the +12V and
the speaker?

--------------------------[switch]-- + 12V
| |
| |
| _ /
|-- |_| 4 ohm speaker
| | \
-------- |
| 8 4 | |
| | |
| 555 | D
| 3|----47R----G IRF530 MOSFET
| | S
| 1 | |
-------- |
| |
| |
-------------------------------- GND

The speaker will have the final say on what
frequencies you get from this. This is a
generally bad design if you are using a
conventional (voice coil and magnet) speaker,
since it applies DC to it and tends to move its
voice coil out of the proper centered position.

The 6.5" car speaker I've got (actually, I've got two) has tweeters on-
board. $20 from Wal-Mart, IIRC. It's pretty much surplus anyway -
unless I can finish building a 10W amplifier...

But that's immaterial here, since you will have a
hard time finding a conventional speaker with much
ultrasonic output. Special tweeters are
available, but they are not cheap.

You could look into piezo tweeters, which are not
only cheap, but are usually used with a DC
blocking cap anyway... and some do go to the
ultrasonic range. The problem is getting enough
power for your purpose. (Actually, the first
problem is getting a data sheet that even mentions
the power output and has a frequency response
plot!)

You could see if there are pre-tuned piezo
oscillators for this type of use. But I think
this is going to be a lot tougher job than you
think. For one thing, how will you know how much
(if any) ultrasonic sound you are getting from
your gadget? If you thought ultrasonic speakers
were expensive, ultrasonic mics are in the $1000+
range!

If the dog shuts up, I guess it's enough power.

I thought 12V would be an improvement over this, which according to
the comments, uses a single 9V battery:

http://www.petsmart.com/product/index.jsp?productId=3006736

Best regards,

Bob Masta

DAQARTA v4.51
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!

Thanks,

Michael



Here is a link to the device your looking for :
http://www.freeinfosociety.com/media/pdf/1281.pdf

use a 2N3055 transistor instead of the D40D5 since they're hard to get ahold
of and use 12 volts. The inductor needs to be a big one to handle the
current. use a horn piezo instead of the small one in the article.

Shaun

 

[gearhead]

On Sep 15, 8:59 am, N0S...@daqarta.com (Bob Masta) wrote:

On Mon, 14 Sep 2009 22:19:07 -0700 (PDT), Michael



mrdarr...@gmail.com> wrote:
For the neighbor's dog.  Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz.  In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea?  I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit?  Should I put a cap between the +12V and
the speaker?

--------------------------[switch]--  + 12V
  |                   |
  |                   |
  |                   _ /
  |--                |_|   4 ohm speaker
  |  |                  \
--------             |
|  8  4  |            |
|        |            |
| 555    |            D
|       3|----47R----G    IRF530 MOSFET
|        |            S
|  1     |            |
--------             |
  |                  |
  |                  |
   -------------------------------- GND

The speaker will have the final say on what
frequencies you get from this.  This is a
generally bad design if you are using a
conventional (voice coil and magnet) speaker,
since it applies DC to it and tends to move its
voice coil out of the proper centered position.  

But that's immaterial here, since you will have a
hard time finding a conventional speaker with much
ultrasonic output.  Special tweeters are
available, but they are not cheap.

You could look into piezo tweeters, which are not
only cheap, but are usually used with a DC
blocking cap anyway... and some do go to the
ultrasonic range.  The problem is getting enough
power for your purpose.  (Actually, the first
problem is getting a data sheet that even mentions
the power output and has a frequency response
plot!)

You could see if there are pre-tuned piezo
oscillators for this type of use.  But I think
this is going to be a lot tougher job than you
think.  For one thing, how will you know how much
(if any) ultrasonic sound you are getting from
your gadget?  If you thought ultrasonic speakers
were expensive, ultrasonic mics are in the $1000+
range!

Best regards,

Bob Masta

              DAQARTA  v4.51
   Data AcQuisition And Real-Time Analysis
             www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
           FREE Signal Generator
        Science with your sound card!

+1 on the piezo, and use a reflector to direct the sound in the
general direction you want. Use a wok or something. A parabola's
focus lies halfway between its apex and the center of curvature at the
apex.
So if you use a spherical surface to approximate a parabolic
reflector, put the piezo halfway between the center of the sphere and
its surface. You don't want a super tight focus. You can spread the
beam by moving the piezo in or out a little bit. You can also put it
off to the side, like they do with tv receiving dishes.

 

[Michael]

On Sep 15, 5:59 am, N0S...@daqarta.com (Bob Masta) wrote:

On Mon, 14 Sep 2009 22:19:07 -0700 (PDT), Michael



mrdarr...@gmail.com> wrote:
For the neighbor's dog.  Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz.  In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea?  I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit?  Should I put a cap between the +12V and
the speaker?

--------------------------[switch]--  + 12V
  |                   |
  |                   |
  |                   _ /
  |--                |_|   4 ohm speaker
  |  |                  \
--------             |
|  8  4  |            |
|        |            |
| 555    |            D
|       3|----47R----G    IRF530 MOSFET
|        |            S
|  1     |            |
--------             |
  |                  |
  |                  |
   -------------------------------- GND

The speaker will have the final say on what
frequencies you get from this.  This is a
generally bad design if you are using a
conventional (voice coil and magnet) speaker,
since it applies DC to it and tends to move its
voice coil out of the proper centered position.  

The 6.5" car speaker I've got (actually, I've got two) has tweeters on-
board. $20 from Wal-Mart, IIRC. It's pretty much surplus anyway -
unless I can finish building a 10W amplifier...

But that's immaterial here, since you will have a
hard time finding a conventional speaker with much
ultrasonic output.  Special tweeters are
available, but they are not cheap.

You could look into piezo tweeters, which are not
only cheap, but are usually used with a DC
blocking cap anyway... and some do go to the
ultrasonic range.  The problem is getting enough
power for your purpose.  (Actually, the first
problem is getting a data sheet that even mentions
the power output and has a frequency response
plot!)

You could see if there are pre-tuned piezo
oscillators for this type of use.  But I think
this is going to be a lot tougher job than you
think.  For one thing, how will you know how much
(if any) ultrasonic sound you are getting from
your gadget?  If you thought ultrasonic speakers
were expensive, ultrasonic mics are in the $1000+
range!

If the dog shuts up, I guess it's enough power.

I thought 12V would be an improvement over this, which according to
the comments, uses a single 9V battery:

http://www.petsmart.com/product/index.jsp?productId=3006736

Best regards,

Bob Masta

              DAQARTA  v4.51
   Data AcQuisition And Real-Time Analysis
             www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
           FREE Signal Generator
        Science with your sound card!

Thanks,

Michael

 

[Shaun]

"Michael" <mrdarrett@gmail.com> wrote in message
news:dad3d263-6f0d-4f12-8336-41ac64e758af@u36g2000prn.googlegroups.com...
On Sep 15, 8:44 am, "Shaun" <sc...@nomail.com> wrote:

"Michael" <mrdarr...@gmail.com> wrote in message

news:b5bf2180-7aa0-4ae3-b864-b7d5b9e2465f@z3g2000prd.googlegroups.com...
On Sep 15, 5:59 am, N0S...@daqarta.com (Bob Masta) wrote:



On Mon, 14 Sep 2009 22:19:07 -0700 (PDT), Michael

mrdarr...@gmail.com> wrote:
For the neighbor's dog. Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz. In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea? I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit? Should I put a cap between the +12V and
the speaker?

--------------------------[switch]-- + 12V
| |
| |
| _ /
|-- |_| 4 ohm speaker
| | \
-------- |
| 8 4 | |
| | |
| 555 | D
| 3|----47R----G IRF530 MOSFET
| | S
| 1 | |
-------- |
| |
| |
-------------------------------- GND

The speaker will have the final say on what
frequencies you get from this. This is a
generally bad design if you are using a
conventional (voice coil and magnet) speaker,
since it applies DC to it and tends to move its
voice coil out of the proper centered position.

The 6.5" car speaker I've got (actually, I've got two) has tweeters on-
board. $20 from Wal-Mart, IIRC. It's pretty much surplus anyway -
unless I can finish building a 10W amplifier...



But that's immaterial here, since you will have a
hard time finding a conventional speaker with much
ultrasonic output. Special tweeters are
available, but they are not cheap.

You could look into piezo tweeters, which are not
only cheap, but are usually used with a DC
blocking cap anyway... and some do go to the
ultrasonic range. The problem is getting enough
power for your purpose. (Actually, the first
problem is getting a data sheet that even mentions
the power output and has a frequency response
plot!)

You could see if there are pre-tuned piezo
oscillators for this type of use. But I think
this is going to be a lot tougher job than you
think. For one thing, how will you know how much
(if any) ultrasonic sound you are getting from
your gadget? If you thought ultrasonic speakers
were expensive, ultrasonic mics are in the $1000+
range!

If the dog shuts up, I guess it's enough power.

I thought 12V would be an improvement over this, which according to
the comments, uses a single 9V battery:

http://www.petsmart.com/product/index.jsp?productId=3006736

Best regards,

Bob Masta

DAQARTA v4.51
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!

Thanks,

Michael

Here is a link to the device your looking for
:http://www.freeinfosociety.com/media/pdf/1281.pdf

use a 2N3055 transistor instead of the D40D5 since they're hard to get
ahold
of and use 12 volts. The inductor needs to be a big one to handle the
current. use a horn piezo instead of the small one in the article.

Shaun

Thanks. I'll study that circuit. Two inductors, huh?

Did you buy the kit? I was looking for an embedded magazine title but
didn't see one.

Michael


I didn't buy the kit, just built it from a book "Build you own laser phaser
ion ray gun" many years ago.
You should know that using one of these will affect you too, even though
it's pointed away from you, so use with caution!

BTW: the inductor closest to the transistor is a small transformer, I think
it 8 ohm to 1000 Ohm impedance matching transformer. You used to be able to
get them from Radio Shack.

Shaun

 

[Michael]

On Sep 15, 8:44 am, "Shaun" <sc...@nomail.com> wrote:

"Michael" <mrdarr...@gmail.com> wrote in message

news:b5bf2180-7aa0-4ae3-b864-b7d5b9e2465f@z3g2000prd.googlegroups.com...
On Sep 15, 5:59 am, N0S...@daqarta.com (Bob Masta) wrote:



On Mon, 14 Sep 2009 22:19:07 -0700 (PDT), Michael

mrdarr...@gmail.com> wrote:
For the neighbor's dog. Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz. In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea? I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit? Should I put a cap between the +12V and
the speaker?

--------------------------[switch]-- + 12V
| |
| |
| _ /
|-- |_| 4 ohm speaker
| | \
-------- |
| 8 4 | |
| | |
| 555 | D
| 3|----47R----G IRF530 MOSFET
| | S
| 1 | |
-------- |
| |
| |
-------------------------------- GND

The speaker will have the final say on what
frequencies you get from this. This is a
generally bad design if you are using a
conventional (voice coil and magnet) speaker,
since it applies DC to it and tends to move its
voice coil out of the proper centered position.

The 6.5" car speaker I've got (actually, I've got two) has tweeters on-
board.  $20 from Wal-Mart, IIRC.  It's pretty much surplus anyway -
unless I can finish building a 10W amplifier...



But that's immaterial here, since you will have a
hard time finding a conventional speaker with much
ultrasonic output. Special tweeters are
available, but they are not cheap.

You could look into piezo tweeters, which are not
only cheap, but are usually used with a DC
blocking cap anyway... and some do go to the
ultrasonic range. The problem is getting enough
power for your purpose. (Actually, the first
problem is getting a data sheet that even mentions
the power output and has a frequency response
plot!)

You could see if there are pre-tuned piezo
oscillators for this type of use. But I think
this is going to be a lot tougher job than you
think. For one thing, how will you know how much
(if any) ultrasonic sound you are getting from
your gadget? If you thought ultrasonic speakers
were expensive, ultrasonic mics are in the $1000+
range!

If the dog shuts up, I guess it's enough power.

I thought 12V would be an improvement over this, which according to
the comments, uses a single 9V battery:

http://www.petsmart.com/product/index.jsp?productId=3006736

Best regards,

Bob Masta

DAQARTA v4.51
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!

Thanks,

Michael

Here is a link to the device your looking for :http://www.freeinfosociety..com/media/pdf/1281.pdf

use a 2N3055 transistor instead of the D40D5 since they're hard to get ahold
of and use 12 volts.  The inductor needs to be a big one to handle the
current.  use a horn piezo instead of the small one in the article.

Shaun

Thanks. I'll study that circuit. Two inductors, huh?

Did you buy the kit? I was looking for an embedded magazine title but
didn't see one.

Michael

 

[Roger Dewhurst]

Michael wrote:

For the neighbor's dog. Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz.

That range is audio. Go for about 40kHz.

Think about an ultrasonic dog whistle and then figure out how you are
going to blow air through it. That might be easier.

R





In a bit of a hurry at the moment, so no C, R1

and R2 chosen yet, but is this a good idea? I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit? Should I put a cap between the +12V and
the speaker?



--------------------------[switch]-- + 12V
| |
| |
| _ /
|-- |_| 4 ohm speaker
| | \
-------- |
| 8 4 | |
| | |
| 555 | D
| 3|----47R----G IRF530 MOSFET
| | S
| 1 | |
-------- |
| |
| |
-------------------------------- GND

 

[Don Klipstein]

In article <h96mr6$nhj$3@lust.ihug.co.nz>, Roger Dewhurst wrote:

Michael wrote:
For the neighbor's dog. Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz.

That range is audio. Go for about 40kHz.

Think about an ultrasonic dog whistle and then figure out how you are
going to blow air through it. That might be easier.

In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea? I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit? Should I put a cap between the +12V and
the speaker?

--------------------------[switch]-- + 12V
| |
| |
| _ /
|-- |_| 4 ohm speaker
| | \
-------- |
| 8 4 | |
| | |
| 555 | D
| 3|----47R----G IRF530 MOSFET
| | S
| 1 | |
-------- |
| |
| |
-------------------------------- GND

What I have usually heard for getting attention of dogs is 25 KHz, not
40. You want the frequency to be barely too high to be audible to humans.

Meanwhile, I would try one of those piezoelectric type loudspeakers
rather than a 4 ohm one. The piezoelectric ones usually do well at 25 KHz
or even higher, preferably the ones smaller than the larger 2.5 by 6.5
inch or whatever horn one. Loudspeakers with voice coils tend to not do
as well at frequencies that high, even if they are tweeters. And I have
found small fullrange loudspeakers such as 2.25 inch "transistor radio"
ones to do poorly even in upper audio frequencies.

A piezoelectric loudspeaker is a primarily capacitive load, and you
should have a 10 ohm resistor in parallel with it to discharge its series
capacitance if you use the above circuit.

- Don Klipstein (don@misty.com)

 

[Shaun]

"Don Klipstein" <don@manx.misty.com> wrote in message
news:slrnhbfrir.dkc.don@manx.misty.com...

In article <h96mr6$nhj$3@lust.ihug.co.nz>, Roger Dewhurst wrote:
Michael wrote:
For the neighbor's dog. Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz.

That range is audio. Go for about 40kHz.

Think about an ultrasonic dog whistle and then figure out how you are
going to blow air through it. That might be easier.

In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea? I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit? Should I put a cap between the +12V and
the speaker?

--------------------------[switch]-- + 12V
| |
| |
| _ /
|-- |_| 4 ohm speaker
| | \
-------- |
| 8 4 | |
| | |
| 555 | D
| 3|----47R----G IRF530 MOSFET
| | S
| 1 | |
-------- |
| |
| |
-------------------------------- GND

What I have usually heard for getting attention of dogs is 25 KHz, not
40. You want the frequency to be barely too high to be audible to humans.

Meanwhile, I would try one of those piezoelectric type loudspeakers
rather than a 4 ohm one. The piezoelectric ones usually do well at 25 KHz
or even higher, preferably the ones smaller than the larger 2.5 by 6.5
inch or whatever horn one. Loudspeakers with voice coils tend to not do
as well at frequencies that high, even if they are tweeters. And I have
found small fullrange loudspeakers such as 2.25 inch "transistor radio"
ones to do poorly even in upper audio frequencies.

A piezoelectric loudspeaker is a primarily capacitive load, and you
should have a 10 ohm resistor in parallel with it to discharge its series
capacitance if you use the above circuit.

- Don Klipstein (don@misty.com)

Don,

If you put a 10 ohm resistor in parallel with the piezo tweeter you'll use
up all the available energy and waste it in heat. If you've followed with
thread, I posted a link to a schematic that uses series / parallel resonance
(using inductors) with the piezo to amplify the voltage across it. A 10 Ohm
resistor would kill the resonance. Try following the thread completely.

Shaun

 

[Don Klipstein]

In article <9xVtm.189076$cf6.901@newsfe16.iad>, Shaun wrote:

"Don Klipstein" <don@manx.misty.com> wrote in message
news:slrnhbfrir.dkc.don@manx.misty.com...
In article <h96mr6$nhj$3@lust.ihug.co.nz>, Roger Dewhurst wrote:
Michael wrote:
For the neighbor's dog. Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz.

That range is audio. Go for about 40kHz.

Think about an ultrasonic dog whistle and then figure out how you are
going to blow air through it. That might be easier.

In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea? I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit? Should I put a cap between the +12V and
the speaker?

--------------------------[switch]-- + 12V
| |
| |
| _ /
|-- |_| 4 ohm speaker
| | \
-------- |
| 8 4 | |
| | |
| 555 | D
| 3|----47R----G IRF530 MOSFET
| | S
| 1 | |
-------- |
| |
| |
-------------------------------- GND

What I have usually heard for getting attention of dogs is 25 KHz, not
40. You want the frequency to be barely too high to be audible to humans.

Meanwhile, I would try one of those piezoelectric type loudspeakers
rather than a 4 ohm one. The piezoelectric ones usually do well at 25 KHz
or even higher, preferably the ones smaller than the larger 2.5 by 6.5
inch or whatever horn one. Loudspeakers with voice coils tend to not do
as well at frequencies that high, even if they are tweeters. And I have
found small fullrange loudspeakers such as 2.25 inch "transistor radio"
ones to do poorly even in upper audio frequencies.

A piezoelectric loudspeaker is a primarily capacitive load, and you
should have a 10 ohm resistor in parallel with it to discharge its series
capacitance if you use the above circuit.

- Don Klipstein (don@misty.com)


Don,

If you put a 10 ohm resistor in parallel with the piezo tweeter you'll use
up all the available energy and waste it in heat. If you've followed with
thread, I posted a link to a schematic that uses series / parallel resonance
(using inductors) with the piezo to amplify the voltage across it. A 10 Ohm
resistor would kill the resonance. Try following the thread completely.

Sorry, I do not have fullest monitoring of threads here, because I have
to spend a lot of time working for a living.

Meanwhile, I think so far here that I have done a goodly 75%-plus
attribution for my comment here in this thread, and I need help to see
how I failed to mention you.

Can you help me out here?

- Don Klipstein (don@misty.com)

 

[Shaun]

"Don Klipstein" <don@manx.misty.com> wrote in message
news:slrnhbgico.hic.don@manx.misty.com...

In article <9xVtm.189076$cf6.901@newsfe16.iad>, Shaun wrote:

"Don Klipstein" <don@manx.misty.com> wrote in message
news:slrnhbfrir.dkc.don@manx.misty.com...
In article <h96mr6$nhj$3@lust.ihug.co.nz>, Roger Dewhurst wrote:
Michael wrote:
For the neighbor's dog. Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz.

That range is audio. Go for about 40kHz.

Think about an ultrasonic dog whistle and then figure out how you are
going to blow air through it. That might be easier.

In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea? I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit? Should I put a cap between the +12V and
the speaker?

--------------------------[switch]-- + 12V
| |
| |
| _ /
|-- |_| 4 ohm speaker
| | \
-------- |
| 8 4 | |
| | |
| 555 | D
| 3|----47R----G IRF530 MOSFET
| | S
| 1 | |
-------- |
| |
| |
-------------------------------- GND

What I have usually heard for getting attention of dogs is 25 KHz, not
40. You want the frequency to be barely too high to be audible to
humans.

Meanwhile, I would try one of those piezoelectric type loudspeakers
rather than a 4 ohm one. The piezoelectric ones usually do well at 25
KHz
or even higher, preferably the ones smaller than the larger 2.5 by 6.5
inch or whatever horn one. Loudspeakers with voice coils tend to not do
as well at frequencies that high, even if they are tweeters. And I have
found small fullrange loudspeakers such as 2.25 inch "transistor radio"
ones to do poorly even in upper audio frequencies.

A piezoelectric loudspeaker is a primarily capacitive load, and you
should have a 10 ohm resistor in parallel with it to discharge its
series
capacitance if you use the above circuit.

- Don Klipstein (don@misty.com)


Don,

If you put a 10 ohm resistor in parallel with the piezo tweeter you'll use
up all the available energy and waste it in heat. If you've followed with
thread, I posted a link to a schematic that uses series / parallel
resonance
(using inductors) with the piezo to amplify the voltage across it. A 10
Ohm
resistor would kill the resonance. Try following the thread completely.

Sorry, I do not have fullest monitoring of threads here, because I have
to spend a lot of time working for a living.

Meanwhile, I think so far here that I have done a goodly 75%-plus
attribution for my comment here in this thread, and I need help to see
how I failed to mention you.

Can you help me out here?

- Don Klipstein (don@misty.com)

Your English is very poor, is English your second language? or are you just
stupid?
I can't understand what you're trying to say.

Shaun

 

[Michael]

On Sep 15, 10:54 am, "Shaun" <sc...@nomail.com> wrote:

"Michael" <mrdarr...@gmail.com> wrote in message

news:dad3d263-6f0d-4f12-8336-41ac64e758af@u36g2000prn.googlegroups.com...
On Sep 15, 8:44 am, "Shaun" <sc...@nomail.com> wrote:



"Michael" <mrdarr...@gmail.com> wrote in message

news:b5bf2180-7aa0-4ae3-b864-b7d5b9e2465f@z3g2000prd.googlegroups.com...
On Sep 15, 5:59 am, N0S...@daqarta.com (Bob Masta) wrote:

On Mon, 14 Sep 2009 22:19:07 -0700 (PDT), Michael

mrdarr...@gmail.com> wrote:
For the neighbor's dog. Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz. In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea? I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit? Should I put a cap between the +12V and
the speaker?

--------------------------[switch]-- + 12V
| |
| |
| _ /
|-- |_| 4 ohm speaker
| | \
-------- |
| 8 4 | |
| | |
| 555 | D
| 3|----47R----G IRF530 MOSFET
| | S
| 1 | |
-------- |
| |
| |
-------------------------------- GND

The speaker will have the final say on what
frequencies you get from this. This is a
generally bad design if you are using a
conventional (voice coil and magnet) speaker,
since it applies DC to it and tends to move its
voice coil out of the proper centered position.

The 6.5" car speaker I've got (actually, I've got two) has tweeters on-
board. $20 from Wal-Mart, IIRC. It's pretty much surplus anyway -
unless I can finish building a 10W amplifier...

But that's immaterial here, since you will have a
hard time finding a conventional speaker with much
ultrasonic output. Special tweeters are
available, but they are not cheap.

You could look into piezo tweeters, which are not
only cheap, but are usually used with a DC
blocking cap anyway... and some do go to the
ultrasonic range. The problem is getting enough
power for your purpose. (Actually, the first
problem is getting a data sheet that even mentions
the power output and has a frequency response
plot!)

You could see if there are pre-tuned piezo
oscillators for this type of use. But I think
this is going to be a lot tougher job than you
think. For one thing, how will you know how much
(if any) ultrasonic sound you are getting from
your gadget? If you thought ultrasonic speakers
were expensive, ultrasonic mics are in the $1000+
range!

If the dog shuts up, I guess it's enough power.

I thought 12V would be an improvement over this, which according to
the comments, uses a single 9V battery:

http://www.petsmart.com/product/index.jsp?productId=3006736

Best regards,

Bob Masta

DAQARTA v4.51
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!

Thanks,

Michael

Here is a link to the device your looking for
:http://www.freeinfosociety.com/media/pdf/1281.pdf

use a 2N3055 transistor instead of the D40D5 since they're hard to get
ahold
of and use 12 volts. The inductor needs to be a big one to handle the
current. use a horn piezo instead of the small one in the article.

Shaun

Thanks.  I'll study that circuit.  Two inductors, huh?

Did you buy the kit?  I was looking for an embedded magazine title but
didn't see one.

Michael

I didn't buy the kit, just built it from a book "Build you own laser phaser
ion ray gun" many years ago.
You should know that using one of these will affect you too, even though
it's pointed away from you, so use with caution!

BTW:  the inductor closest to the transistor is a small transformer, I think
it 8 ohm to 1000 Ohm impedance matching transformer.  You used to be able to
get them from Radio Shack.

Shaun

I finally found a piezo element from a door alarm from the 99 Cent
store. Took it apart, and it looks like this one:

http://www.projectsunlimited.com/audioproducts/movieclips/products/drawings/APS4812B-LW100-R.pdf

Are those specs typical?

I'm wondering if I can wind my own 500 uH inductor L1 using the
inductor design equation.

Would a TIP31A work, or must I use a 2N3055?

Thanks,

Michael

 

[Shaun]

"Michael" <mrdarrett@gmail.com> wrote in message
news:3fc20a11-91bb-440a-adb7-53440947009a@v15g2000prn.googlegroups.com...
On Sep 15, 10:54 am, "Shaun" <sc...@nomail.com> wrote:

"Michael" <mrdarr...@gmail.com> wrote in message

news:dad3d263-6f0d-4f12-8336-41ac64e758af@u36g2000prn.googlegroups.com...
On Sep 15, 8:44 am, "Shaun" <sc...@nomail.com> wrote:



"Michael" <mrdarr...@gmail.com> wrote in message

news:b5bf2180-7aa0-4ae3-b864-b7d5b9e2465f@z3g2000prd.googlegroups.com...
On Sep 15, 5:59 am, N0S...@daqarta.com (Bob Masta) wrote:

On Mon, 14 Sep 2009 22:19:07 -0700 (PDT), Michael

mrdarr...@gmail.com> wrote:
For the neighbor's dog. Heard about the ultrasonic noisemakers that
are triggered by a dog's bark, but at $50 and several unfavorable
comments, thought I'd try to roll my own.

Aiming for 16-20 kHz. In a bit of a hurry at the moment, so no C, R1
and R2 chosen yet, but is this a good idea? I've got a couple spare
12V lead acid batteries lying about, and a couple of spare 4 ohm car
speakers (10 watt max), so I'm thinking of using them to amplify a
square wave:

Any comments on this circuit? Should I put a cap between the +12V and
the speaker?

--------------------------[switch]-- + 12V
| |
| |
| _ /
|-- |_| 4 ohm speaker
| | \
-------- |
| 8 4 | |
| | |
| 555 | D
| 3|----47R----G IRF530 MOSFET
| | S
| 1 | |
-------- |
| |
| |
-------------------------------- GND

The speaker will have the final say on what
frequencies you get from this. This is a
generally bad design if you are using a
conventional (voice coil and magnet) speaker,
since it applies DC to it and tends to move its
voice coil out of the proper centered position.

The 6.5" car speaker I've got (actually, I've got two) has tweeters on-
board. $20 from Wal-Mart, IIRC. It's pretty much surplus anyway -
unless I can finish building a 10W amplifier...

But that's immaterial here, since you will have a
hard time finding a conventional speaker with much
ultrasonic output. Special tweeters are
available, but they are not cheap.

You could look into piezo tweeters, which are not
only cheap, but are usually used with a DC
blocking cap anyway... and some do go to the
ultrasonic range. The problem is getting enough
power for your purpose. (Actually, the first
problem is getting a data sheet that even mentions
the power output and has a frequency response
plot!)

You could see if there are pre-tuned piezo
oscillators for this type of use. But I think
this is going to be a lot tougher job than you
think. For one thing, how will you know how much
(if any) ultrasonic sound you are getting from
your gadget? If you thought ultrasonic speakers
were expensive, ultrasonic mics are in the $1000+
range!

If the dog shuts up, I guess it's enough power.

I thought 12V would be an improvement over this, which according to
the comments, uses a single 9V battery:

http://www.petsmart.com/product/index.jsp?productId=3006736

Best regards,

Bob Masta

DAQARTA v4.51
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!

Thanks,

Michael

Here is a link to the device your looking for
:http://www.freeinfosociety.com/media/pdf/1281.pdf

use a 2N3055 transistor instead of the D40D5 since they're hard to get
ahold
of and use 12 volts. The inductor needs to be a big one to handle the
current. use a horn piezo instead of the small one in the article.

Shaun

Thanks. I'll study that circuit. Two inductors, huh?

Did you buy the kit? I was looking for an embedded magazine title but
didn't see one.

Michael

I didn't buy the kit, just built it from a book "Build you own laser
phaser
ion ray gun" many years ago.
You should know that using one of these will affect you too, even though
it's pointed away from you, so use with caution!

BTW: the inductor closest to the transistor is a small transformer, I
think
it 8 ohm to 1000 Ohm impedance matching transformer. You used to be able
to
get them from Radio Shack.

Shaun

I finally found a piezo element from a door alarm from the 99 Cent
store. Took it apart, and it looks like this one:

http://www.projectsunlimited.com/audioproducts/movieclips/products/drawings/APS4812B-LW100-R.pdf

Are those specs typical?

I'm wondering if I can wind my own 500 uH inductor L1 using the
inductor design equation.

Would a TIP31A work, or must I use a 2N3055?

Thanks,

Michael

I don't think that piezo speaker will work. The one's I used I could buy
from radio shack in there car audio or home audio section. Or another place
I found (which has gone out of business) was an electronics supply store
that had car audio stuff (speakers). These piezo speakers are meant to
replace the tweeter with a speaker that can reproduce really high
frequencies.

do a google search for "motorola piezo tweeter" it comes up with several.
One place to buy them is ebay.
http://cgi.ebay.com/4-Pcs-Piezo-Tweeters-Replacement-for-Motorola-KSN1005A_W0QQitemZ330363604362QQcmdZViewItem

then 500 uH inductors could be hand wound, but that's allot of winding or
buy them from a store that sells speaker parts, they're used in crossovers.

The transistor......... I don't know if it will work.


Shaun