Author Topic: Identify speaker  (Read 1673 times)

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Offline fixit7Topic starter

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Identify speaker
« on: May 25, 2019, 04:18:37 pm »
This is from a cordless phone.

I think it is a speaker.

Phone uses 2.4 volt battery.

I was wondering if it would work in a 9 Vdc circuit?

https://www.dropbox.com/s/yy6rwm0vib91010/PhoneSpeaker.jpg?dl=0
 

Offline PA0PBZ

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Re: Identify speaker
« Reply #1 on: May 25, 2019, 06:45:20 pm »
Yes it is a speaker, and the characteristics are printed on it. Since a speaker is driven with AC your question about 9V DC is irrelevant.
Keyboard error: Press F1 to continue.
 

Offline mikerj

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Re: Identify speaker
« Reply #2 on: May 25, 2019, 06:54:50 pm »
Yes it is a speaker, and the characteristics are printed on it. Since a speaker is driven with AC your question about 9V DC is irrelevant.

Not entirely irrelevant.  A 9v pk-pk signal across that 150ohm speaker would be around 68mw, more than double it's rated power.

A high impedance driver like that could be driven directly from the output of an op-amp.
 

Offline fixit7Topic starter

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Re: Identify speaker
« Reply #3 on: May 25, 2019, 08:42:14 pm »
Yes it is a speaker, and the characteristics are printed on it. Since a speaker is driven with AC your question about 9V DC is irrelevant.

Was not aware it was an AC speaker.

 

Online Zero999

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Re: Identify speaker
« Reply #4 on: May 25, 2019, 10:14:39 pm »
Yes it is a speaker, and the characteristics are printed on it. Since a speaker is driven with AC your question about 9V DC is irrelevant.

Was not aware it was an AC speaker.
All speakers need to be driven from AC. The sound they produce mirrors the AC waveform. For example put in 1VAC at 1kHz and it will produce a 1kHz tone. There are limits of course the the upper and lower ends of the frequency response. This telephone speaker is probably only good for a narrow frequency range of 300Hz to 3kHz.

The only things which beep and work off DC are buzzers, basically a simple speaker with a built-in oscillator which converts the applied DC voltage to AC to drive the speaker. The oscillator in a buzzer can be either electronic (normally just a transistor with feedbacl) or electromechanical: basically a relay with a normal closed contact wired in series with the coil and the moving iron attached to a diaphragm to improve the coupling of the vibrations to the air.
 
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Offline fixit7Topic starter

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Re: Identify speaker
« Reply #5 on: May 26, 2019, 12:44:30 am »
Yes it is a speaker, and the characteristics are printed on it. Since a speaker is driven with AC your question about 9V DC is irrelevant.

Was not aware it was an AC speaker.
All speakers need to be driven from AC. The sound they produce mirrors the AC waveform. For example put in 1VAC at 1kHz and it will produce a 1kHz tone. There are limits of course the the upper and lower ends of the frequency response. This telephone speaker is probably only good for a narrow frequency range of 300Hz to 3kHz.

The only things which beep and work off DC are buzzers, basically a simple speaker with a built-in oscillator which converts the applied DC voltage to AC to drive the speaker. The oscillator in a buzzer can be either electronic (normally just a transistor with feedbacl) or electromechanical: basically a relay with a normal closed contact wired in series with the coil and the moving iron attached to a diaphragm to improve the coupling of the vibrations to the air.

Thanks.

I have one of these. Does it run on AC?

What is the 5Vp-p?

Piezo Transducer
Electrical Specifications:

    Rated Voltage: 5Vp-p
    Rated Current: 2mA (max)
    Sound Output at 10cm: 85 dBA
    Resonant Frequency: 2.04kHz
 

Offline timelessbeing

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Re: Identify speaker
« Reply #6 on: May 26, 2019, 02:09:56 am »
Vp-p = Peak-to-Peak voltage



Are you trying to make something, or just taking things to bits to see what they do?

http://www.bcae1.com/audoutex.htm
http://www.bcae1.com/speaker.htm
« Last Edit: May 26, 2019, 02:13:16 am by timelessbeing »
 

Offline fixit7Topic starter

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Re: Identify speaker
« Reply #7 on: May 26, 2019, 02:50:22 am »
I made this circuit on a experimenters breadboard.

After I knew it was working, I soldered the components to one of these.

PCB Prototype Circuit Solder BREADBOARD - Discrete and DIP

https://makezine.com/projects/laser-tripwire-alarm/

I made some modifications by adding a piezo buzzer instead of a plain speaker.

I also had to put a 3 inch piece of PVC pipe over the Cadmium PhotoCell to keep non-laser light from affecting the circuit.

 

Offline timelessbeing

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Re: Identify speaker
« Reply #8 on: May 26, 2019, 04:03:23 am »
does it work?
 

Online Zero999

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Re: Identify speaker
« Reply #9 on: May 26, 2019, 07:20:11 am »
That circuit requires a buzzer to work. It will not work with plain speaker or piezo transducer which doesn't have an internal oscillator. It it works, then you're using a buzzer - well done!
 

Offline fixit7Topic starter

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Re: Identify speaker
« Reply #10 on: May 27, 2019, 02:29:45 am »
does it work?

Yes, both the circuit and buzzer work.

The diagram was from the author of the circuit.

I am learning to use Geda to create my own circuit diagrams.

I looked for a symbol for a piezo buzzer. The closest I found looked like a speaker with plus and minus terminals.

It was quite a leaning experience going from the solderless breadboard to soldering the components in the final board.

Learned a lot and it will take quite a bit of practice to get good.

I will eventually need a temp controlled iron as my "Hakko knockoff" was overheating as the dial readings did not correspond to the actual tip temperature.

Andy

Andy
 


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