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17 kilo hertz buzzer

 
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dogsrcool2me
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Joined: 07 Dec 2006
Posts: 2

PostPosted: Thu Dec 07, 2006 8:21 pm    Post subject: 17 kilo hertz buzzer Reply with quote

I have a basic understanding of electronics. Can some one point me in the right direction on how to make a 17 kilo hertz buzzer.

Thank you
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Nginuity
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Joined: 13 Nov 2006
Posts: 224
Location: Dallas, Texas

PostPosted: Thu Dec 07, 2006 8:34 pm    Post subject: Reply with quote

You mean like a piezo buzzer, or a speaker buzzer?
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dogsrcool2me
Newbie


Joined: 07 Dec 2006
Posts: 2

PostPosted: Thu Dec 07, 2006 11:24 pm    Post subject: Reply with quote

pizo would obviously be easier but I couldn't find the right one so speaker buzzer is what I will be building it with
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Nginuity
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Joined: 13 Nov 2006
Posts: 224
Location: Dallas, Texas

PostPosted: Fri Dec 08, 2006 11:34 am    Post subject: Reply with quote

Alright,if you are just wanting to generate a tone to a speaker, you just basically need to build an oscillator. There are several out there, but the most common are Hartley, Colpitts, and Crystal Controlled.

Even better, now that I think about it, I was toying around in the junk room, and I came across my old morse code practice oscillator (That I built in an altoids tin, just so you know!), and it seems like a perhaps easier method for your application. It uses a 555 timer to make the circuit oscillate, in a sense. The only catch that you come upon is that because the 555 timer is a digital device, it will put out a square wave instead of a sine wave, which will actually work to your advantage, because sine waves at higher frequencies get funky.

Parts List (dont go buy them yet, we're gonna modify this):
IC1- 555 timer
R1 - 150k (change to 1K)
R2 - 1K (see below)
C1 - 10 uF electrolytic
C2 - .01 uF ceramic disc
Speaker
9V battery clip (or a 9v DC source)

Here is a quick schematic of the oscillator. Just replace the "key" part with a push button, or whatever you were going to use:


Now, looking at the schematic, in regard to the frequency of the 555 timer, you get the desired frequency by modifying the values of R1, R2, and C2.

The formula is: Frequency = 1.44 / ( (R1+R2+R2) * C), which is derived from f = 1/(.693 x C x (R1 + 2 x R2)) if anyone isn't used to seeing it that way for simplicity, so for the frequency of 17KHz, you end up needing to change R1 to a 1K ohm, and C2 stays the same. For R2, which is somewhere between 3.73 and 3.74K ohm resistance, I suggest you install a potentiometer capable of 500ohm to 1K flexibility in series with 3K worth of resistors to make your finite adjustments to bring it up to 17Khz. In the process of this, I found a neat 555 calculator that I am thinking about mirroring with permission:

http://ourworld.compuserve.com/homepages/Bill_Bowden/555.htm

Last, if anyone finds any errors in the schematic, and more importantly, an error in the math, please, let me know! I'm not perfect. Smile

Have fun!
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