buzzer & transformer

Thread Starter

gatoulisss

Joined Jan 23, 2015
69
hello,
i want to make a piezo buzzer much louder than it is, in many circuits im seeing transformers using like the siren in the picture any ideas how to do this?
im taking the output of a pic16f88 as sound driver for the buzzer.Photo 31-1-15 - 10 20 21 μ.μ..jpg
 

Robartes

Joined Oct 1, 2014
57
That circuit looks like a blocking oscillator. If so, I don't think the transformer in itself has anything to do with making the buzzer louder. One thing to watch out for with piezo buzzers is that they all have a specific resonant frequency at which they are the loudest, and usually fall off quite steeply on either side of that frequency. So to insure a piezo buzzer is loud, make sure you are driving it at its resonant frequency. The datasheet of your buzzer should tell you what that frequency is.
 

Thread Starter

gatoulisss

Joined Jan 23, 2015
69
That circuit looks like a blocking oscillator. If so, I don't think the transformer in itself has anything to do with making the buzzer louder. One thing to watch out for with piezo buzzers is that they all have a specific resonant frequency at which they are the loudest, and usually fall off quite steeply on either side of that frequency. So to insure a piezo buzzer is loud, make sure you are driving it at its resonant frequency. The datasheet of your buzzer should tell you what that frequency is.[ i have
i have also this syren in the foto, the 2 yellow cables are the signal and the ground. thats why im thinking of the trasformer as amplifier but i dont know how it works
 

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ScottWang

Joined Aug 23, 2012
7,397
The first photo with the photo in the 5# are different, I want make sure how is the circuit in the first photo, otherwise only can guess that and may not the same, if you took the first photo, could you take the picture for the solder side?

If the circuit is similar as in the linked page from Robartes, then you can reducing the values of R1, or you can using a 1K in series with a 50K pot to replacing R1 to adjust the base current for bjt.
 
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Thread Starter

gatoulisss

Joined Jan 23, 2015
69
The first photo with the photo in the 5# are different, I want make sure how is the circuit in the first photo, otherwise only can guess that and may not the same, if you took the first photo, could you take the picture for the solder side?

If the circuit is similar as in the linked page from Robartes, then you can reducing the values of R1, or you can using a 1K in series with a 50K pot to replacing R1 to adjust the base current for bjt.
the first picture is from an alarm syren with no drive circuit you just give 9v and sounds the board is just making the sound, i post it to saw you that the buzzer is connected to the transformer... im interesting most of how it works so i can make something like picture in #5 wich is a normal buzzer but sounds much more than without the transformer
 

Robartes

Joined Oct 1, 2014
57
the first picture is from an alarm syren with no drive circuit you just give 9v and sounds the board is just making the sound, i post it to saw you that the buzzer is connected to the transformer... im interesting most of how it works so i can make something like picture in #5 wich is a normal buzzer but sounds much more than without the transformer
It is possible that the transformer's secondary winding has a higher number of turns than the primary so that the buzzer gets a higher peak-to-peak voltage and sounds louder. In the presumed circuit from post #1, this function would be combined with the oscillator function (the transformer serves in the oscillator circuit and increases output voltage). In the presumed circuit of post #5, the transformer would just increase the output voltage from an earlier oscillator stage.
 

Thread Starter

gatoulisss

Joined Jan 23, 2015
69
It is possible that the transformer's secondary winding has a higher number of turns than the primary so that the buzzer gets a higher peak-to-peak voltage and sounds louder. In the presumed circuit from post #1, this function would be combined with the oscillator function (the transformer serves in the oscillator circuit and increases output voltage). In the presumed circuit of post #5, the transformer would just increase the output voltage from an earlier oscillator stage.
so what type of transformer i sould buy and how i connect it so i have output voltage icrease?
 
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