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epilot said:hi
does anyone know the range of freq of these kind of quartz crystal speakers?
does anyone know if they work at 100KHz or more?
Nigel Goodwin said:epilot said:hi
does anyone know the range of freq of these kind of quartz crystal speakers?
does anyone know if they work at 100KHz or more?
It looks to be a standard crystal with the can removed?. It will be highly resonant at one specific frequency, the one it's tuned to, usually in the Mhz region (although lower frequency crystals are available).
I don't see as it's any use as a speaker?.
Dr.EM said:I assume this is the type of device you mean, commonly termed a piezo sounder;
**broken link removed**
audioguru said:Your transducer is not quartz, it is a cheap piezo. It doesn't have gold, most likely it is brass.
It is probably used in the security device as a vibration sensor/microphone, not ultrasonic. It resonates strongly around 4kHz with very little output above or below. As a microphone it will pickup a glass breaking sound.
Expensive ultrasonic transducers resonate around 40kHz with little output above and below.
I don't know of any transducer that can perform as high as 100kHz.
Why do you need such a high frequency?
Your sensors aren't ultrasonic.epilot said:then do you think my ultrasonic sensors will perfprm at 40KHz?
Digikey sells ultrasonic transducers at 3 frequencies. They are very expensive.then if some one wants a 30 or 50KHZ freq what he has to do because such as you said the resonate freq of ultrasonic sensors seems to be near 40KHZ?
I think they are too small and with low power so the range will be very short.i thought about a rangemter and acording to our discussion about ultrasonic and narrow waves i thought perhaps a higher freq buzzer can be good to get more distance, the eson of using buzzers instead of an ultrasonic sensor is because i am not so familiar with them and i read before that they work a freq near 40KHz(please can you explian a bit about them?)
I have never heard of a crystal buzzer. Maybe you mean "ceramic resonator".what is difference between a low cost buzzer and a crystal buzzer?
If they use a very thin plating then it won't cost much. I think it is too heavy for a transducer and isn't needed anyway. Cheap brass is fine.what is the story of "gold"?
audioguru said:Your sensors aren't ultrasonic.epilot said:then do you think my ultrasonic sensors will perfprm at 40KHz?
no, my meam was my ultrasonic sensoors(referred to my earlier post)not my piezo..
Digikey sells ultrasonic transducers at 3 frequencies. They are very expensive.then if some one wants a 30 or 50KHZ freq what he has to do because such as you said the resonate freq of ultrasonic sensors seems to be near 40KHZ?
then does anyone know any alternative?
I think they are too small and with low power so the range will be very short.i thought about a rangemter and acording to our discussion about ultrasonic and narrow waves i thought perhaps a higher freq buzzer can be good to get more distance, the eson of using buzzers instead of an ultrasonic sensor is because i am not so familiar with them and i read before that they work a freq near 40KHz(please can you explian a bit about them?)
i have 2 big buzzers but it seems you mean they can not peform at 100KHZ nor even at 40 or 50KHZ, if i could use from them... :cry:I have never heard of a crystal buzzer. Maybe you mean "ceramic resonator".what is difference between a low cost buzzer and a crystal buzzer?
crystal buzzers are what we call that coin buzzers(the above pics)here in my country, i am not sure what is the real name for that buzzers in english(perhaps such as "Dr.EM"said you call them piezo sounder!
If they use a very thin plating then it won't cost much. I think it is too heavy for a transducer and isn't needed anyway. Cheap brass is fine.what is the story of "gold"?
audioguru said:Google might have a few sentences about a piezo beeper:
"It flexes when AC voltage is applied. It resonates around 4kHz. Commonly used in smoke alarms. It can also be used as a 4kHz microphone."
The piezo beeper transducers I have are much louder with a resonant cavity behind them. A tall bottle cap is good. Sweep the frequency for the loudest peak.
epilot said:i know this coin buzzers abit but i never have worked with ultrasonic sensors so i need help about them too?
i'll try to see if i can find something about them in the net
audioguru said:That's a nice expensive-looking ultrasonic sensor. Post its spec's so we can see if it is a mic or speaker, see how wide or narrow is its beam and how low is its max output power. Then maybe we can figure how much range a pair will make.
audioguru said:I don't know where to buy Velleman stuff. Digikey sells ultrasonic transducers for $26.00US to $120.00US.
epilot said:what about using a normal loudspeaker?