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Ultrasonic speaker or ??

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If you make two sine-waves with opamps and they use a 12V supply then their max output is about 9.6V p-p. The bridged emitter-followers will have an output of 17.6V p-p. If an 8 ohm speaker is used then its RMS signal is only 6.22V and the power is only 4.8W which is not loud. If you use square-waves then the power is doubled but the output level is the same. The piezo tweeter has an output of 94dB at 1m when it is fed the level from an amp that would produce 1W in an 8 ohm speaker.

Your two signals add and subtract but the deer or bears don't care if the amplifier clips a little and makes distortion. They might like the sound.
 
Heaven forbid they like the sound!
The frequencies are going to be random. The PIC has a RAND NUM GEN so the low frequency will randomaly go from 2-8KHZ while the HIGH frequencies will cycle randomally from 15-20KHZ.
Canceling of frequencies would be minimiual I suspect?
As for loudness, The device for the automomobil will need to be louder but not so loud that the driver can hear it driving down the road.
The linl I posted about the HORNET, not sure if it mentions loudness?
It never ceses to amaze me at your knowledge AudioGuru.
Looking at some cheaper piezo "speakers" from PUI audio. They have just the bendable elements?? Not sure if they would suit this app??
 
Here is an item that I bookmarked last year
**broken link removed**
located here in the states.
Now If I can figure out just how loud this gizmo will be?
12v automotive for one device and 5-9v for house hold device.
Both driven off a PIC.
Contemplating the push pull amp I posted earlier. And inputting two different random frequencies 2-5khz for one input and 15-20khz for second input.
Power needed?? need to do some research.
perhaps not build a battery operated device?
 
amperage wattage conversion etc?

using this amp I assume that it puts out 2.4 watts of power?
240ma X 12v = 2.4 watts
the input resistors show very little amperage but the 8 ohm resistor (piezo horn tweeter) shows upwards of 230+ma.
am I in the ballpark or am I missing something?
I need to find the impedance of
**broken link removed**
 

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using this amp I assume that it puts out 2.4 watts of power?
I calculated 4.8W into 8 ohms in an earlier post.
The piezo tweeter is not 8 ohms and its loudness is calculated with the voltage that is produced into 8 ohms.

The GT1016 tweeter is not loud enough with only 4.8W. It is rated at 94dB with 1W (2.83V RMS) at a distance of 1m.
You will feed it 4.8W so its loudness at 1m is 101dB.
It will be 95dB at 2m.
It will be 89db (not very loud) at 4m.
 
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How did you achieve the impedance of the GT1016?
1M is what in feet (I need to find conversion) but the PIR in the home version only detects up to 20-30 feet away.
The automobile version not sure of what distance needed.
Will relocate the specs on the HORNET and its snake oil pitch of WAVE VARIANCE TUNING
 
the HORNET specs
Curious as to how it gets such a range of distance with only 20ma?.24 watts?
# Sound Pressure Level: 135dB (A.S.)
# Operating Base Frequency: 4.8 ± 0.5 kHz
# WV Ultrasonic Wave: 18,000 to 24,000 Hz
# Wave Carrying Length: 2,000 Ft. ±
# Effective Range: 1,000 Ft.
# Operating Voltage Range: 8-16 VDC
# Current Consumption: 20mA (max.) at 12 VDC
# Recommended for interstate travel only
# Not compatible with EZ-Mount Bracket
 
How did you achieve the impedance of the GT1016?
The impedance doesn't matter because it is not a coil and magnet speaker. It is a piezo which is like a capacitor. Its output level is rated at the voltage that an amplifier produces 1W in 8 ohms.

1M is what in feet (I need to find conversion)
Welcome to the real world. Most of the world is metric now.
1m is about 39 inches which is a little over 3 feet.

But the PIR in the home version only detects up to 20-30 feet away.
A PIR uses infrared not an audible high frequency. It has a high gain amplifier inside to detect motion of something warm.

The automobile version not sure of what distance needed.
Will relocate the specs on the HORNET and its snake oil pitch of WAVE VARIANCE TUNING
It has no technical details. It probably doesn't work.
 
Thats my thought.
It says 1000 feet range but only 20ma of current?
I located several (5) 7.5W mono amp IC's that I purchased from Goldmine several months ago. Should aid in building an amp?
Looking at maybe a bigger amp just for vehicle use.
My LOML said I can purchase some of the GT1016 tweeter horns.
then maybe start experimenting with.
Found a website that showed a pienzo tweeter driven off a PIC using PWM. Wonder If I am getting to deep in this project?
Maybe just stick with the PIC code, add the extra frequencies and devise a switch to turn on at 15-20mph.
 
Lets get MORE POWER?but it says for a 4ohm output.
How to determine this using a pienzo or just add an 4ohm resistor??
A resistor will simply waste power.

The datasheet for the TDA1518 and for every other ordinary car radio bridged amplifier IC shows that its output is 22W at a horrible-sounding 10% distortion (it is clipping like crazy because its volume control is turned up too high) into a 4 ohm speaker and when its supply is 14.4V. Its output is only 10.1W at clipping into 4 ohms when its supply is 12.0V. Then its output voltage is 6.4V RMS which produces only 5W into 8 ohms.
 
The spec for a speaker includes a frequency response graph. The Maplin "piezo whistles" do not have a graph.
 
The spec for a speaker includes a frequency response graph. The Maplin "piezo whistles" do not have a graph.

The application is for (hopefully) scaring away deer, I doubt an accurate frequency response would much concern them :p

The spec on the units is up to 40KHz, and is all he really needs to know - and is certainly by FAR the cheapest solution he's going to come across.
 
why go a bigger amp. The tweeters I ordered are 50watt, 94dB
**broken link removed**
**broken link removed**
This is not a hi-fi sound system for deer. I don't want to entertain them, just want to scare the daylights outta them.
can get some 24w stereo (2x12wBTL amp chip TDA1518BQ fairly cheap ($1 but sale ends 5/1/10)
SALE! TDA1518BQ 2x12Watt Stereo Power Amplifier-The Electronic Goldmine
or go with a bigger amp
TDA8560Q 40Watt/2 Ohm Stereo Amplifier IC (Phillips)-The Electronic Goldmine
but at $2.49 I don't think so.
Plan is for vehicle use, an amplifier with two speakers, each speaker driven with 12w.
One amp has random input frequiencies of 2 - 8 khz
second amp input has random frequencies of 15-20khz.(might go higher as the tweeter is rated for up to 27khz)
all frequencies selected using a RAND NUM GEN code in a PIC.
One must realize deer can hear up to 1 mile away with directional hearing ability.
for home garden use, a battery powered unit with only one small speaker, no amp.
I need to see if the pic code will generate the 15-20khz.
a way to turn on the vehicle unit at 15-20mph.Thinking a ping pong ball in a tube w/ photo transistor circuitry.
I have 3 of each piezo tweeters ordered last night.
 
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